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Sample records for quarks und leptonen

  1. Quark Masses

    SciTech Connect (OSTI)

    Gasser, Juerg

    2005-10-26

    In my talk, I reviewed some basic aspects of quark masses: what do they mean, how can they be determined, what is our present knowledge on them. The talk was addressed to non specialists in the field, and so is this write up.

  2. Hormann Energie und Umwelt | Open Energy Information

    Open Energy Info (EERE)

    Hormann Energie und Umwelt Jump to: navigation, search Name: Hormann Energie und Umwelt Place: Munchen, Germany Sector: Geothermal energy Product: Munchen-based energy and...

  3. Cold quark matter in compact stars

    SciTech Connect (OSTI)

    Franzon, B.; Fogaca, D. A.; Navarra, F. S.; Horvath, J. E.

    2013-03-25

    We used an equation of state for the cold quark matter to the study of properties of quark stars. We also discuss the absolute stability of quark matter and compute the mass-radius relation for self-bound stars.

  4. The Discovery of the Top Quark

    DOE R&D Accomplishments [OSTI]

    Sinervo, P.K.

    1995-12-01

    The top quark and the Higgs boson are the heaviest elementary particles predicted by the standard model. The four lightest quark flavours, the up, down, strange and charm quarks, were well-established by the mid-1970's. The discovery in 1977 of the {Tau} resonances, a new family of massive hadrons, required the introduction of the fifth quark flavour. Experimental and theoretical studies have indicated that this quark also has a heavier partner, the top quark.

  5. Quark Gluon Plasma

    SciTech Connect (OSTI)

    Lincoln, Don

    2015-05-07

    Matter is malleable and can change its properties with temperature. This is most familiar when comparing ice, liquid water and steam, which are all different forms of the same thing. However beyond the usual states of matter, physicists can explore other states, both much colder and hotter. In this video, Fermilabs Dr. Don Lincoln explains the hottest known state of matter a state that is so hot that protons and neutrons from the center of atoms can literally melt. This form of matter is called a quark gluon plasma and it is an important research topic being pursued at the LHC.

  6. Quarks Pair Up in Protons (and Neutrons) | Jefferson Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Quarks Pair Up in Protons (and Neutrons) Graph of up quark/down quark contributions Researchers have published intriguing new observations for how the different kinds of quarks behave inside protons and neutrons. In the proton, the down quark contributes surprisingly little to electron-proton interaction. Also, the up quark contributes much less to electron-neutron interaction than one would expect if all three quarks behaved in similar ways. Quarks Pair Up in Protons (and Neutrons) Ordinarily,

  7. Heavy hadrons in quark-gluon plasma

    SciTech Connect (OSTI)

    Narodetskii, I. M. Simonov, Yu. A.; Veselov, A. I.

    2011-03-15

    We use the nonperturbative quark-antiquark potential derived within the Field Correlator Method and the screened Coulomb potential to calculate binding energies and melting temperatures of heavy mesons and baryons in the deconfined phase of quark-gluon plasma.

  8. Giese Energie und Regeltechnik GmbH | Open Energy Information

    Open Energy Info (EERE)

    Giese Energie und Regeltechnik GmbH Jump to: navigation, search Name: Giese Energie- und Regeltechnik GmbH Place: Puchheim bei Mnchen, Germany Zip: 82178 Product: Micro...

  9. Cooking Up Hot Quark Soup

    DOE R&D Accomplishments [OSTI]

    Walsh, Karen McNulty

    2011-03-28

    Near-light-speed collisions of gold ions provide a recipe for in-depth explorations of matter and fundamental forces. The Relativistic Heavy Ion Collider (RHIC) has produced the most massive antimatter nucleus ever discovered—and the first containing an anti-strange quark. The presence of strange antimatter makes this antinucleus the first to be entered below the plane of the classic Periodic Table of Elements, marking a new frontier in physics.

  10. Measurements of Top Quark Properties

    SciTech Connect (OSTI)

    Cerrito, Lucio

    2009-05-01

    Preliminary results on the measurement of four selected properties of the top quark are presented. The relative fraction of t{bar t} production through gluon fusion has been measured in the t{bar t} dilepton decay channel by the CDF Collaboration as F{sub gg} = 0.53{sub -0.38}{sup +0.36}. Using an integrated luminosity of 2.7 fb{sup -1} collected with the CDF II detector, we also determine the t{bar t} differential cross section with respect to values up to {approx}1 TeV of the t{bar t} invariant mass. We present a model-independent measurement of the helicity of W bosons produced in top quark decays, using an integrated luminosity of up to 2.7 fb{sup -1} collected by the D0 detector, and find the fraction of longitudinal W bosons f{sub 0} = 0.49 {+-} 0.14, and the fraction of right-handed W bosons f{sub +} = 0.11 {+-} 0.08. Finally, we measure the parton level forward-backward asymmetry of pair produced top quarks using an integrated luminosity of 3.2 fb{sup -1} collected with the CDF II detector, and find A{sub FB} = 0.19 {+-} 0.07. All results are consistent with the predictions of the standard model.

  11. Top Quark Production Asymmetries AFBt and AFBl

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Berger, Edmond L.; Cao, Qing-Hong; Chen, Chuan-Ren; Yu, Jiang-Hao; Zhang, Hao

    2012-02-14

    A large forward-backward asymmetry is seen in both the top quark rapidity distribution AFBt and in the rapidity distribution of charged leptons AFBl from top quarks produced at the Tevatron. We study the kinematic and dynamic aspects of the relationship of the two observables arising from the spin correlation between the charged lepton and the top quark with different polarization states. We emphasize the value of both measurements, and we conclude that a new physics model which produces more right-handed than left-handed top quarks is favored by the present data.

  12. Press Pass - Press Release - Single top quark

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Higgs." Discovering the single top quark production presents challenges similar to the Higgs boson search in the need to extract an extremely small signal from a very large...

  13. CP Violation in Single Top Quark Production

    SciTech Connect (OSTI)

    Geng, Weigang

    2012-01-01

    We present a search for CP violation in single top quark production with the DØ experiment at the Tevatron proton-antiproton collider. CP violation in the top electroweak interaction results in different single top quark production cross sections for top and antitop quarks. We perform the search in the single top quark final state using 5.4 fb-1 of data, in the s-channel, t-channel, and for both combined. At this time, we do not see an observable CP asymmetry.

  14. Review of meson spectroscopy: quark states and glueballs

    SciTech Connect (OSTI)

    Chanowitz, M.S.

    1981-11-01

    A group of three lectures on hadron spectroscopy are presented. Topics covered include: light L = 0 mesons, light L = 1 mesons, antiquark antiquark quark quark exotics, a catalogue of higher quark antiquark excitations, heavy quarkonium, and glueballs. (GHT)

  15. Hadronic physics of q anti q light quark mesons, quark molecules and glueballs

    SciTech Connect (OSTI)

    Lindenbaum, S.J.

    1980-10-01

    A brief introduction reviews the development of QCD and defines quark molecules and glueballs. This review is concerned primarily with u, d, and s quarks, which provide practically all of the cross section connected with hadronic interactions. The following topics form the bulk of the paper: status of quark model classification for conventional u, d, s quark meson states; status of multiquark or quark molecule state predictions and experiments; glueballs and how to find them; and the OZI rule in decay and production and how glueballs might affect it. 17 figures, 1 table. (RWR)

  16. Sea quark transverse momentum distributions and dynamical chiral...

    Office of Scientific and Technical Information (OSTI)

    Sea quark transverse momentum distributions and dynamical chiral symmetry breaking Citation Details In-Document Search Title: Sea quark transverse momentum distributions and...

  17. Top quark pair production cross section at Tevatron (Conference...

    Office of Scientific and Technical Information (OSTI)

    Conference: Top quark pair production cross section at Tevatron Citation Details In-Document Search Title: Top quark pair production cross section at Tevatron You are accessing ...

  18. Recent Developments in Heavy Quark and Quarkonium Production...

    Office of Scientific and Technical Information (OSTI)

    Conference: Recent Developments in Heavy Quark and Quarkonium Production Citation Details In-Document Search Title: Recent Developments in Heavy Quark and Quarkonium Production ...

  19. Top quark pair production cross section at Tevatron (Conference...

    Office of Scientific and Technical Information (OSTI)

    Conference: Top quark pair production cross section at Tevatron Citation Details In-Document Search Title: Top quark pair production cross section at Tevatron An overview of the ...

  20. Top Quark Anomalous Couplings at the International Linear Collider...

    Office of Scientific and Technical Information (OSTI)

    Quark Anomalous Couplings at the International Linear Collider Citation Details In-Document Search Title: Top Quark Anomalous Couplings at the International Linear Collider We ...

  1. Heavy Quarks, QCD, and Effective Field Theory Thomas Mehen 72...

    Office of Scientific and Technical Information (OSTI)

    Heavy Quarks, QCD, and Effective Field Theory Thomas Mehen 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS Heavy Quarks, Quarkonium,...

  2. Chiral transition and mesonic excitations for quarks with thermal...

    Office of Scientific and Technical Information (OSTI)

    We study the effect of a thermal quark mass, msub T, on the chiral phase transition and ... D QUARKS; EXCITATION; LANDAU DAMPING; MASS; PARTICLE DECAY; PHASE TRANSFORMATIONS; ...

  3. HUNTING THE QUARK GLUON PLASMA.

    SciTech Connect (OSTI)

    LUDLAM, T.; ARONSON, S.

    2005-04-11

    The U.S. Department of Energy's Relativistic Heavy Ion Collider (RHIC) construction project was completed at BNL in 1999, with the first data-taking runs in the summer of 2000. Since then the early measurements at RHIC have yielded a wealth of data, from four independent detectors, each with its international collaboration of scientists: BRAHMS, PHENIX, PHOBOS, and STAR [1]. For the first time, collisions of heavy nuclei have been carried out at colliding-beam energies that have previously been accessible only for high-energy physics experiments with collisions of ''elementary'' particles such as protons and electrons. It is at these high energies that the predictions of quantum chromodynamics (QCD), the fundamental theory that describes the role of quarks and gluons in nuclear matter, come into play, and new phenomena are sought that may illuminate our view of the basic structure of matter on the sub-atomic scale, with important implications for the origins of matter on the cosmic scale. The RHIC experiments have recorded data from collisions of gold nuclei at the highest energies ever achieved in man-made particle accelerators. These collisions, of which hundreds of millions have now been examined, result in final states of unprecedented complexity, with thousands of produced particles radiating from the nuclear collision. All four of the RHIC experiments have moved quickly to analyze these data, and have begun to understand the phenomena that unfold from the moment of collision as these particles are produced. In order to provide benchmarks of simpler interactions against which to compare the gold-gold collisions, the experiments have gathered comparable samples of data from collisions of a very light nucleus (deuterium) with gold nuclei, as well as proton-proton collisions, all with identical beam energies and experimental apparatus. The early measurements have revealed compelling evidence for the existence of a new form of nuclear matter at extremely high density and temperature--a medium in which the predictions of QCD can be tested, and new phenomena explored, under conditions where the relevant degrees of freedom, over nuclear volumes, are expected to be those of quarks and gluons, rather than of hadrons. This is the realm of the quark gluon plasma, the predicted state of matter whose existence and properties are now being explored by the RHIC experiments.

  4. Heavy-quark physics in quantum chromodynamics

    SciTech Connect (OSTI)

    Brodsky, S.J.

    1991-04-01

    Heavy quarks can expose new symmetries and novel phenomena in QCD not apparent in ordinary hadronic systems. In these lectures I discuss the use of effective-Lagrangian and light-cone Fock methods to analyze exclusive heavy hadron decays such as {Upsilon} {yields} p{bar p} and B {yields} {pi}{pi}, and also to derive effective Schroedinger and Dirac equations for heavy quark systems. Two contributions to the heavy quark structure functions of the proton and other light hadrons are identified: an extrinsic'' contribution associated with leading twist QCD evolution of the gluon distribution, and a higher twist intrinsic'' contribution due to the hardness of high-mass fluctuations of multi-gluon correlations in hadronic wavefunctions. A non-perturbative calculation of the heavy quark distribution of a meson in QCD in one space and one time is presented. The intrinsic higher twist contributions to the pion and proton structure functions can dominate the hadronic production of heavy quark systems at large longitudinal momentum fraction x{sub F} and give anomalous contributions to the quark structure functions of ordinary hadrons at large x{sub bj}. I also discuss a number of ways in which heavy quark production in nuclear targets can test fundamental QCD phenomena and provide constraints on hadronic wavefunctions. The topics include color transparency, finite formation time, and predictions for charm production at threshold, including nuclear-bound quarkonium. I also discuss a number of QCD mechanisms for the suppression of J/{psi} and {Upsilon} production in nuclear collisions, including gluon shadowing, the peripheral excitation of intrinsic heavy quark components at large x{sub F}, and the coalescence of heavy quarks with co-moving spectators at low x{sub F}.

  5. Measurement of top quark polarisation in t-channel single top quark production

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-11-09

    Our first measurement of the top quark spin asymmetry, sensitive to the top quark polarisation, in t-channel single top quark production is presented. It is based on a sample of pp collisions at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb-1. A high-purity sample of t-channel single top quark events with an isolated muon is selected. Signal and background components are estimated using a fit to data. Furthermore, a differential cross section measurement, corrected for detector effects, of an angular observable sensitive to the top quark polarisation is performed. The differential distribution is used to extract a top quark spin asymmetry of 0.26 ± 0.03 (stat) ± 0.10 (syst), which is compatible with a p-value of 4.6% with the standard model prediction of 0.44.

  6. Quark-gluon correlation functions relevant to single transverse spin

    Office of Scientific and Technical Information (OSTI)

    asymmetries (Journal Article) | SciTech Connect Quark-gluon correlation functions relevant to single transverse spin asymmetries Citation Details In-Document Search Title: Quark-gluon correlation functions relevant to single transverse spin asymmetries We investigate the relative size of various twist-3 quark-gluon correlation functions relevant to single transverse spin asymmetries (SSAs) in a quark-diquark model of the nucleon. We calculate the quark-gluon correlation function T{sub

  7. Dark Decay of the Top Quark

    SciTech Connect (OSTI)

    Kong, Kyoungchul; Lee, Hye-Sung; Park, Myeonghun

    2014-04-01

    We suggest top quark decays as a venue to search for light dark force carriers. The top quark is the heaviest particle in the standard model whose decays are relatively poorly measured, allowing sufficient room for exotic decay modes from new physics. A very light (GeV scale) dark gauge boson (Z') is a recently highlighted hypothetical particle that can address some astrophysical anomalies as well as the 3.6sigma deviation in the muon g-2 measurement. We present and study a possible scenario that top quark decays as t-->bW+Z's. This is the same as the dominant top quark decay (t-->bW) accompanied by one or multiple dark force carriers. The Z' can be easily boosted, and it can decay into highly collimated leptons (lepton-jet) with large branching ratio. We discuss the implications for the Large Hadron Collider experiments including the analysis based on the lepton-jets.

  8. Dark decay of the top quark

    SciTech Connect (OSTI)

    Kong, Kyoungchul; Lee, Hye -Sung; Park, Myeonghun

    2014-04-01

    We suggest top quark decays as a venue to search for light dark force carriers. Top quark is the heaviest particle in the standard model whose decays are relatively poorly measured, allowing sufficient room for exotic decay modes from new physics. A very light (GeV scale) dark gauge boson (Z') is a recently highlighted hypothetical particle that can address some astrophysical anomalies as well as the 3.6 ? deviation in the muon g-2 measurement. We present and study a possible scenario that top quark decays as t ? b W + Z's. This is the same as the dominant top quark decay (t ? b W) accompanied by one or multiple dark force carriers. The Z' can be easily boosted, and it can decay into highly collimated leptons (lepton-jet) with large branching ratio. In addition, we discuss the implications for the Large Hadron Collider experiments including the analysis based on the lepton-jets.

  9. An Unquenched Quark Model of Baryons

    SciTech Connect (OSTI)

    Bijker, Roelof; Santopinto, Elena

    2007-10-26

    We present the formalism for a new generation of unquenched quark models for baryons in which the effects of quark-antiquark pairs are taken into account in an explicit form via a microscopic, QCD-inspired, quark-antiquark creation mechanism. The present approach is an extension of the fiux-tube breaking model of Geiger and Isgur in which now the contribution of quark-antiquark pairs can be studied for any inital baryon, for any fiavor of the qq-bar pair (not only ss-bar but also uu-bar and dd-bar) and for arbitrary hadron wave functions. The method is illustrated with an application to the spin of the proton and the flavor asymmetry of the nucleon sea.

  10. Evidence for production of single top quarks

    SciTech Connect (OSTI)

    Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Aguilo, E.; Ahn, S.H.; Ahsan, M.; Alexeev, G.D.; Alkhazov, G.; /St. Petersburg, INP /Michigan U.

    2008-03-01

    We present first evidence for the production of single top quarks in the D0 detector at the Fermilab Tevatron p{bar p} collider. The standard model predicts that the electroweak interaction can produce a top quark together with an antibottom quark or light quark, without the antiparticle top quark partner that is always produced from strong coupling processes. Top quarks were first observed in pair production in 1995, and since then, single top quark production has been searched for in ever larger datasets. In this analysis, we select events from a 0.9 fb{sup -1} dataset that have an electron or muon and missing transverse energy from the decay of a W boson from the top quark decay, and two, three, or four jets, with one or two of the jets identified as originating from a b hadron decay. The selected events are mostly backgrounds such as W+jets and t{bar t} events, which we separate from the expected signals using three multivariate analysis techniques: boosted decision trees, Bayesian neural networks, and matrix element calculations. A binned likelihood fit of the signal cross section plus background to the data from the combination of the results from the three analysis methods gives a cross section for single top quark production of {sigma}(p{bar p} {yields} tb + X, tqb + X) = 4.7 {+-} 1.3 pb. The probability to measure a cross section at this value or higher in the absence of signal is 0.014%, corresponding to a 3.6 standard deviation significance. The measured cross section value is compatible at the 10% level with the standard model prediction for electroweak top quark production. We use the cross section measurement to directly determine the Cabibbo-Kobayashi-Maskawa quark mixing matrix element that describes the Wtb coupling and find |V{sub tb}f{sub 1}{sup L}| = 1.31{sub -0.21}{sup +0.25}, where f{sub 1}{sup L} is a generic vector coupling. This model-independent measurement translates into 0.68 < |V{sub tb}| {le} 1 at the 95% C.L. in the standard model.

  11. New Mechanism for Quark Energy Loss

    SciTech Connect (OSTI)

    Casalderrey-Solana, Jorge; Fernandez, Daniel; Mateos, David

    2010-04-30

    We show that a heavy quark moving sufficiently fast through a quark-gluon plasma may lose energy by Cherenkov-radiating mesons. We demonstrate that this takes place in all strongly coupled, large-N{sub c} plasmas with a gravity dual. The energy loss is exactly calculable in these models despite being an O(1/N{sub c}) effect. We discuss implications for heavy-ion collision experiments.

  12. GM Umwelt und Energiewirtschaft GmbH | Open Energy Information

    Open Energy Info (EERE)

    Umwelt und Energiewirtschaft GmbH Jump to: navigation, search Name: GM Umwelt- und Energiewirtschaft GmbH Place: Dresden, Germany Zip: 1257 Sector: Wind energy Product: German wind...

  13. Measurement of the top quark pair production cross section in...

    Office of Scientific and Technical Information (OSTI)

    Measurement of the top quark pair production cross section in proton-proton collisions at sqrts13 TeV Citation Details In-Document Search Title: Measurement of the top quark...

  14. Heavy Quarks, QCD, and Effective Field Theory (Technical Report...

    Office of Scientific and Technical Information (OSTI)

    Heavy Quarks, QCD, and Effective Field Theory Citation Details In-Document Search Title: Heavy Quarks, QCD, and Effective Field Theory The research supported by this OJI award is ...

  15. Top quark mass measurements at CDF

    SciTech Connect (OSTI)

    Brubaker, Erik; /Chicago U., EFI

    2006-05-01

    The mass of the top quark M{sub top} is interesting both as a fundamental parameter of the standard model and as an important input to precision electroweak tests. The Collider Detector at Fermilab (CDF) has a robust program of top quark mass analyses, including the most precise single measurement, M{sub top} = 173.4 {+-} 2.8 GeV/c{sup 2}, using 680 pb{sup -1} of p{bar p} collision data. A combination of current results from CDF gives M{sub top} = 172.0 {+-} 2.7 GeV/c{sup 2}, surpassing the stated goal of 3 GeV/c{sup 2} precision using 2 fb{sup -1} of data. Finally, a combination with current D0 results gives a world average top quark mass of 172.5 {+-} 2.3 GeV/c{sup 2}.

  16. The heavy top quark and supersymmetry

    SciTech Connect (OSTI)

    Hall, L.J.

    1997-01-01

    Three aspects of supersymmetric theories are discussed: electroweak symmetry breaking, the issues of flavor, and gauge unification. The heavy top quark plays an important, sometimes dominant, role in each case. Additional symmetries lead to extensions of the Standard Model which can provide an understanding for many of the outstanding problems of particle physics. A broken supersymmetric extension of spacetime allows electroweak symmetry breaking to follow from the dynamics of the heavy top quark; an extension of isospin provides a constrained framework for understanding the pattern of quark and lepton masses; and a grand unified extension of the Standard Model gauge group provides an elegant understanding of the gauge quantum numbers of the components of a generation. Experimental signatures for each of these additional symmetries are discussed.

  17. Dissociation of a heavy meson in the quark medium

    SciTech Connect (OSTI)

    Park, Chanyong

    2010-02-15

    We investigate the dissociation of a heavy meson in the medium composed of light quarks and gluons. In the quark-gluon plasma, the dissociation length of the heavy meson becomes short as the temperature or quark chemical potential increases. On the contrary, in the hadronic phase the dissociation length becomes large as the chemical potential increases, due to the different dissociation mechanism with one used in the quark-gluon plasma.

  18. Adomian Decomposition Method for Quark Gluon Plasma Model

    SciTech Connect (OSTI)

    Constantinescu, Radu; Ionescu, Carmen; Stoicescu, Mihai

    2011-10-03

    The paper investigates the possibility of obtaining analytical solutions for the Quark Gluon Plasma model using the Adomian decomposition method.

  19. Quark mass variation constraints from Big Bang nucleosynthesis (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Quark mass variation constraints from Big Bang nucleosynthesis Citation Details In-Document Search Title: Quark mass variation constraints from Big Bang nucleosynthesis We study the impact on the primordial abundances of light elements created of a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and reaction rates in a

  20. MARTINI event generator for heavy quarks: Initialization, parton...

    Office of Scientific and Technical Information (OSTI)

    Initialization, parton evolution, and hadronization Prev Next Title: MARTINI event generator for heavy quarks: Initialization, parton evolution, and hadronization ...

  1. Debye mass and heavy quark potential in a PNJL quark plasma

    SciTech Connect (OSTI)

    Jankowski, J. Blaschke, D.

    2012-07-15

    We calculate the Debye mass for the screening of the heavy quark potential in a plasma of massless quarks coupled to the temporal gluon background governed by the Polyakov loop potential within the PNJL model in RPA approximation. We give a physical motivation for a recent phenomenological fit of lattice data by applying the calculated Debye mass with its suppression in the confined phase due to the Polyakov loop to a description of the temperature dependence of the singlet free energy for QCD with a heavy quark pair at infinite separation. We compare the result to lattice data.

  2. Precision Determination of the Top Quark Mass

    SciTech Connect (OSTI)

    Movilla Fernandez, Pedro A.; /LBL, Berkeley

    2007-05-01

    The CDF and D0 collaborations have updated their measurements of the mass of the top quark using proton-antiproton collisions at {radical}s = 1.96 TeV produced at the Tevatron. The uncertainties in each of the top-antitop decay channels have been reduced. The new Tevatron average for the mass of the top quark based on about 1 fb{sup -1} of data per experiment is 170.9 {+-} 1.8 GeV/c{sup 2}.

  3. Quark matter and meson properties in a Nonlocal SU(3) chiral quark model at finite temperature

    SciTech Connect (OSTI)

    Gomez Dumm, D.; Contrera, G. A.

    2012-06-15

    We study the finite temperature behavior of light scalar and pseudoscalar meson properties in the context of a three-flavor nonlocal chiral quark model. The model includes mixing with active strangeness degrees of freedom, and takes care of the effect of gauge interactions by coupling the quarks with a background color field. We analyze the chiral restoration and deconfinement transitions, as well as the temperature dependence of meson masses, mixing angles, and decay constants.

  4. Quark-gluon plasma (Selected Topics)

    SciTech Connect (OSTI)

    Zakharov, V. I.

    2012-09-15

    Introductory lectures to the theory of (strongly interacting) quark-gluon plasma given at the Winter School of Physics of ITEP (Moscow, February 2010). We emphasize theoretical issues highlighted by the discovery of the low viscosity of the plasma. The topics include relativistic hydrodynamics, manifestations of chiral anomaly in hydrodynamics, superfluidity, relativistic superfluid hydrodynamics, effective stringy scalars, holographic models of Yang-Mills theories.

  5. Dark decay of the top quark

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kong, Kyoungchul; Lee, Hye -Sung; Park, Myeonghun

    2014-04-01

    We suggest top quark decays as a venue to search for light dark force carriers. Top quark is the heaviest particle in the standard model whose decays are relatively poorly measured, allowing sufficient room for exotic decay modes from new physics. A very light (GeV scale) dark gauge boson (Z') is a recently highlighted hypothetical particle that can address some astrophysical anomalies as well as the 3.6 σ deviation in the muon g-2 measurement. We present and study a possible scenario that top quark decays as t → b W + Z's. This is the same as the dominant topmore » quark decay (t → b W) accompanied by one or multiple dark force carriers. The Z' can be easily boosted, and it can decay into highly collimated leptons (lepton-jet) with large branching ratio. In addition, we discuss the implications for the Large Hadron Collider experiments including the analysis based on the lepton-jets.« less

  6. Quark-Gluon Plasma Model and Origin of Magic Numbers

    SciTech Connect (OSTI)

    Ghahramany, N.; Ghanaatian, M.; Hooshmand, M.

    2008-04-21

    Using Boltzman distribution in a quark-gluon plasma sample it is possible to obtain all existing magic numbers and their extensions without applying the spin and spin-orbit couplings. In this model it is assumed that in a quark-gluon thermodynamic plasma, quarks have no interactions and they are trying to form nucleons. Considering a lattice for a central quark and the surrounding quarks, using a statistical approach to find the maximum number of microstates, the origin of magic numbers is explained and a new magic number is obtained.

  7. Quarkyonic Matter and Quark Number Scaling of Elliptic Flow

    SciTech Connect (OSTI)

    Csernai, L. P.; Zschocke, S.; Horvat, Sz.; Cheng Yun; Mishustin, I. N.

    2011-05-23

    The constituent quark number scaling of elliptic flow is studied in a non-equilibrium hadronization and freeze-out model with rapid dynamical transition from ideal, deconfined and chirally symmetric Quark Gluon Plasma, to final non-interacting hadrons. In this transition a Bag model of constituent quarks is considered, where the quarks gain constituent quark mass while the background Bag-field breaks up and vanishes. The constituent quarks then recombine into simplified hadron states, while chemical, thermal and flow equilibrium break down one after the other. In this scenario the resulting temperatures and flow velocities of baryons and mesons are different. Using a simplified few source model of the elliptic flow, we are able to reproduce the constituent quark number scaling, with assumptions on the details of the non-equilibrium processes.

  8. WA_06_016_BP_SOLAR_INTERNATIONAL_Waiver_of_Patent_Rights_Und...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    06016BPSOLARINTERNATIONALWaiverofPatentRightsUnd.pdf WA06016BPSOLARINTERNATIONALWaiverofPatentRightsUnd.pdf PDF icon WA06016BPSOLARINTERNATIONALWaiverofP...

  9. Union zur F rderung von Oel und Proteinpflanzen Ufop | Open Energy...

    Open Energy Info (EERE)

    zur F rderung von Oel und Proteinpflanzen Ufop Jump to: navigation, search Name: Union zur Frderung von Oel- und Proteinpflanzen (Ufop) Place: Germany Product: Germany-based...

  10. Quarkonia and heavy-quark relaxation times in the quark-gluon plasma

    SciTech Connect (OSTI)

    Riek, F.; Rapp, R.

    2010-09-15

    A thermodynamic T-matrix approach for elastic two-body interactions is employed to calculate spectral functions of open and hidden heavy-quark systems in the quark-gluon plasma. This enables the evaluation of quarkonium bound-state properties and heavy-quark diffusion on a common basis and thus to obtain mutual constraints. The two-body interaction kernel is approximated within a potential picture for spacelike momentum transfers. An effective field-theoretical model combining color-Coulomb and confining terms is implemented with relativistic corrections and for different color channels. Four pertinent model parameters, characterizing the coupling strengths and screening, are adjusted to reproduce the color-average heavy-quark free energy as computed in thermal lattice QCD. The approach is tested against vacuum spectroscopy in the open (D, B) and hidden ({Psi} and {Upsilon}) flavor sectors, as well as in the high-energy limit of elastic perturbative QCD scattering. Theoretical uncertainties in the static reduction scheme of the four-dimensional Bethe-Salpeter equation are elucidated. The quarkonium spectral functions are used to calculate Euclidean correlators which are discussed in light of lattice QCD results, while heavy-quark relaxation rates and diffusion coefficients are extracted utilizing a Fokker-Planck equation.

  11. Rare top quark decays in extended models

    SciTech Connect (OSTI)

    Gaitan, R.; Miranda, O. G.; Cabral-Rosetti, L. G.

    2006-09-25

    Flavor changing neutral currents (FCNC) decays t {yields} H0 + c, t {yields} Z + c, and H0 {yields} t + c-bar are discussed in the context of Alternative Left-Right symmetric Models (ALRM) with extra isosinglet heavy fermions where FCNC decays may take place at tree-level and are only suppressed by the mixing between ordinary top and charm quarks, which is poorly constraint by current experimental values. The non-manifest case is also briefly discussed.

  12. Baryon Spectroscopy and the Constituent Quark Model

    SciTech Connect (OSTI)

    A.W. Thomas; R.D. Young

    2005-07-26

    We explore further the idea that the lattice QCD data for hadron properties in the region m[^2][_pi] > 0.2GeV^2 can be described by the constituent quark model. This leads to a natural explanation of the fact that nucleon excited states are generally stable for pion masses greater than their physical excitation energies. Finally, we apply these same ideas to the problem of how pentaquarks might behave in lattice QCD, with interesting conclusions.

  13. Exotic quarks in Twin Higgs models

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Cheng, Hsin -Chia; Jung, Sunghoon; Salvioni, Ennio; Tsai, Yuhsin

    2016-03-14

    The Twin Higgs model provides a natural theory for the electroweak symmetry breaking without the need of new particles carrying the standard model gauge charges below a few TeV. In the low energy theory, the only probe comes from the mixing of the Higgs fields in the standard model and twin sectors. However, an ultraviolet completion is required below ~ 10 TeV to remove residual logarithmic divergences. In non-supersymmetric completions, new exotic fermions charged under both the standard model and twin gauge symmetries have to be present to accompany the top quark, thus providing a high energy probe of themore » model. Some of them carry standard model color, and may therefore be copiously produced at current or future hadron colliders. Once produced, these exotic quarks can decay into a top together with twin sector particles. If the twin sector particles escape the detection, we have the irreducible stop-like signals. On the other hand, some twin sector particles may decay back into the standard model particles with long lifetimes, giving spectacular displaced vertex signals in combination with the prompt top quarks. This happens in the Fraternal Twin Higgs scenario with typical parameters, and sometimes is even necessary for cosmological reasons. We study the potential displaced vertex signals from the decays of the twin bottomonia, twin glueballs, and twin leptons in the Fraternal Twin Higgs scenario. As a result, depending on the details of the twin sector, the exotic quarks may be probed up to ~ 2.5 TeV at the LHC and beyond 10 TeV at a future 100 TeV collider, providing a strong test of this class of ultraviolet completions.« less

  14. Magnetic Phases in Dense Quark Matter

    SciTech Connect (OSTI)

    Incera, Vivian de la

    2007-10-26

    In this paper I discuss the magnetic phases of the three-flavor color superconductor. These phases can take place at different field strengths in a highly dense quark system. Given that the best natural candidates for the realization of color superconductivity are the extremely dense cores of neutron stars, which typically have very large magnetic fields, the magnetic phases here discussed could have implications for the physics of these compact objects.

  15. Exotic decays of heavy B quarks

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Fox, Patrick J.; Tucker-Smith, David

    2016-01-08

    Heavy vector-like quarks of charge –1/3, B, have been searched for at the LHC through the decays B → bZ, bh, tW. In models where the B quark also carries charge under a new gauge group, new decay channels may dominate. We focus on the case where the B is charged under a U(1)' and describe simple models where the dominant decay mode is B → bZ' → b(bb¯¯). With the inclusion of dark matter such models can explain the excess of gamma rays from the Galactic center. We develop a search strategy for this decay chain and estimate thatmore » with integrated luminosity of 300 fb–1 the LHC will have the potential to discover both the B and the Z' for B quarks with mass below ~ 1.6 TeV, for a broad range of Z' masses. Furthermore, a high-luminosity run can extend this reach to 2 TeV.« less

  16. Tracking down hyper-boosted top quarks

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Larkoski, Andrew J.; Maltoni, Fabio; Selvaggi, Michele

    2015-06-05

    The identification of hadronically decaying heavy states, such as vector bosons, the Higgs, or the top quark, produced with large transverse boosts has been and will continue to be a central focus of the jet physics program at the Large Hadron Collider (LHC). At a future hadron collider working at an order-of-magnitude larger energy than the LHC, these heavy states would be easily produced with transverse boosts of several TeV. At these energies, their decay products will be separated by angular scales comparable to individual calorimeter cells, making the current jet substructure identification techniques for hadronic decay modes not directlymore » employable. In addition, at the high energy and luminosity projected at a future hadron collider, there will be numerous sources for contamination including initial- and final-state radiation, underlying event, or pile-up which must be mitigated. We propose a simple strategy to tag such "hyper-boosted" objects that defines jets with radii that scale inversely proportional to their transverse boost and combines the standard calorimetric information with charged track-based observables. By means of a fast detector simulation, we apply it to top quark identification and demonstrate that our method efficiently discriminates hadronically decaying top quarks from light QCD jets up to transverse boosts of 20 TeV. Lastly, our results open the way to tagging heavy objects with energies in the multi-TeV range at present and future hadron colliders.« less

  17. The Top Quark, Its Discovery, and Subsequent Research

    Office of Scientific and Technical Information (OSTI)

    The Top Quark, Its Discovery, and Subsequent Research Resources with Additional Information 'Ever since the existence of the bottom (or b) quark was inferred from the discovery of the Upsilon family of resonances at Fermilab in 1977, particle physicists have been on the lookout for its partner, called top (or t). The long search, which occupied experimenters at laboratories around the world, came to a successful conclusion in February 1995 with the announcement that the top quark had been

  18. Moving Quarks Help Solve Proton Spin Puzzle | Jefferson Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Moving Quarks Help Solve Proton Spin Puzzle Moving Quarks Help Solve Proton Spin Puzzle NEWPORT NEWS, VA., Sept. 11, 2008 - New theory work at the U.S. Department of Energy's Thomas Jefferson National Accelerator Facility has shown that more than half of the spin of the proton is the result of the movement of its building blocks: quarks. The result, published in the Sept. 5 issue of Physical Review Letters, agrees with recent experiments and supercomputer calculations. It was thought that the

  19. Quark-Gluon Plasma: a New State of Matter

    SciTech Connect (OSTI)

    Brookhaven Lab

    2009-07-08

    Physicist Peter Steinberg explains the nature of the quark gluon plasma (QGP), a new state of matter produced at Brookhaven Lab's Relativistic Heavy Ion Collider (RHIC).

  20. Electromagnetic form factors and the hypercentral constituent quark model

    SciTech Connect (OSTI)

    Sanctis, M. De; Giannini, M. M.; Santopinto, E.; Vassallo, A.

    2007-12-15

    We present new results concerning the electromagnetic form factors of the nucleon using a relativistic version of the hypercentral constituent quark model and a relativistic current.

  1. Sea quark transverse momentum distributions and dynamical chiral...

    Office of Scientific and Technical Information (OSTI)

    The qualitative difference between valence and sea quark intrinsic psub T. distributions ... May 2013 Publisher: World Scientific Research Org: Thomas Jefferson National ...

  2. Quark mass variation constraints from Big Bang nucleosynthesis...

    Office of Scientific and Technical Information (OSTI)

    Quark mass variation constraints from Big Bang nucleosynthesis Citation Details ... way we use lattice QCD data and an hierarchy of effective field theories. ...

  3. Quark mass variation constraints from Big Bang nucleosynthesis...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Quark mass variation constraints from Big Bang nucleosynthesis Citation ... way we use lattice QCD data and an hierarchy of effective field theories. ...

  4. Quark-Gluon Plasma: a New State of Matter

    ScienceCinema (OSTI)

    Brookhaven Lab

    2010-01-08

    Physicist Peter Steinberg explains the nature of the quark gluon plasma (QGP), a new state of matter produced at Brookhaven Lab's Relativistic Heavy Ion Collider (RHIC).

  5. Top Quark Physics at the Tevatron (Journal Article) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Top Quark Physics at the Tevatron Citation Details In-Document Search Title: Top Quark Physics at the Tevatron The authors review the field of top-quark physics ...

  6. Flavor Physics in the Quark Sector

    SciTech Connect (OSTI)

    Antonelli, Mario; Asner, David Mark; Bauer, Daniel Adams; Becher, Thomas G.; Beneke, M.; Bevan, Adrian John; Blanke, Monika; Bloise, C.; Bona, Marcella; Bondar, Alexander E.; Bozzi, Concezio; Brod, Joachim; Buras, Andrzej J.; Cabibbo, N.; Carbone, A.; Cavoto, Gianluca; Cirigliano, Vincenzo; Ciuchini, Marco; Coleman, Jonathon P.; Cronin-Hennessy, Daniel P.; Dalseno, J.P.; /KEK, Tsukuba /Glasgow U. /Queen Mary, U. of London /Freiburg U. /Charles U. /Pisa U. /Vienna, OAW /Imperial Coll., London /Bergen U. /INFN, Rome /Rome U. /Munich, Tech. U. /INFN, Rome /Rome U. /Southampton U. /INFN, Rome /Nara Women's U. /Florida U. /INFN, Turin /Turin U. /Edinburgh U. /Warwick U. /INFN, Rome /Rome U. /Massachusetts U., Amherst /KEK, Tsukuba /Bern U. /CERN /Munich, Tech. U. /Mainz U., Inst. Phys. /Wayne State U. /Munich, Max Planck Inst. /CERN /Frascati /Brookhaven /Mainz U., Inst. Kernphys. /Munich, Tech. U. /Siegen U. /Imperial Coll., London /Victoria U. /KEK, Tsukuba /Fermilab /Washington U., St. Louis /Frascati /Warwick U. /Indian Inst. Tech., Madras /Melbourne U. /Princeton U. /Beijing, Inst. High Energy Phys. /INFN, Rome /INFN, Rome3 /Fermilab /SLAC /York U., Canada /Brookhaven /UC, Irvine /INFN, Rome /Rome U. /Valencia U., IFIC /INFN, Padua /Padua U. /Munich, Max Planck Inst. /Barcelona U. /Warwick U. /Tata Inst. /Frascati /Mainz U., Inst. Phys. /Vienna U. /KEK, Tsukuba /Orsay, LPT /Frascati /Munich, Tech. U. /Brookhaven /Bern U. /CERN /Mainz U., Inst. Phys. /Wayne State U. /Valencia U., IFIC /CERN /Kentucky U. /Oxford U. /Iowa State U. /Bristol U. /INFN, Rome /Rutherford /CERN /Orsay, LAL /Glasgow U. /INFN, Padua /Queen Mary, U. of London /Texas U. /LPHE, Lausanne /Fermilab /UC, Santa Cruz /Vienna, OAW /Cincinnati U. /Frascati /Orsay, LAL /Ohio State U. /Purdue U. /Novosibirsk, IYF /Frascati /INFN, Rome /Padua U. /INFN, Rome /Bern U. /Karlsruhe U. /Brookhaven /CERN /Paris U., VI-VII /Zurich, ETH /Pisa U. /Frascati /Oxford U. /Orsay, LAL /INFN, Rome2 /INFN, Rome /INFN, Rome3 /Princeton U. /Fermilab /Queen's U., Kingston /KEK, Tsukuba /Melbourne U. /Brookhaven /Indiana U. /INFN, Rome /Rome U. /Pisa U. /Mainz U., Inst. Phys. /Karlsruhe U. /Oxford U. /Cambridge U., DAMTP /Edinburgh U. /CERN

    2010-08-26

    In the past decade, one of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor. In this time frame, measurements and the theoretical interpretation of their results have advanced tremendously. A much broader understanding of flavor particles has been achieved, apart from their masses and quantum numbers, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. In the past, observations of CP violation were confined to neutral K mesons, but since the early 1990s, a large number of CP-violating processes have been studied in detail in neutral B mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of K,D, and B mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments, thus a review of the status of quark flavor physics is timely. This report is the result of the work of the physicists attending the 5th CKM workshop, hosted by the University of Rome 'La Sapienza', September 9-13, 2008. It summarizes the results of the current generation of experiments that is about to be completed and it confronts these results with the theoretical understanding of the field which has greatly improved in the past decade.

  7. Nucleon g{sub 2} Structure Function and Quark-Gluon Correlations...

    Office of Scientific and Technical Information (OSTI)

    Nucleon gsub 2 Structure Function and Quark-Gluon Correlations Citation Details In-Document Search Title: Nucleon gsub 2 Structure Function and Quark-Gluon Correlations We ...

  8. VariableR reclustering in multiple top quark events - Oral Presentatio...

    Office of Scientific and Technical Information (OSTI)

    VariableR reclustering in multiple top quark events - Oral Presentation Citation Details In-Document Search Title: VariableR reclustering in multiple top quark events - Oral...

  9. Precision measurement of the top quark mass in the lepton + jets...

    Office of Scientific and Technical Information (OSTI)

    ... FERMILAB TEVATRON; INTERMEDIATE BOSONS; LEPTONS; LUMINOSITY; MATRIX ELEMENTS; NEURAL NETWORKS; QUARKS; RESOLUTION; T QUARKS Experiment-HEP Word Cloud More Like This Full Text ...

  10. Precision measurement of the top quark mass in the lepton + jets...

    Office of Scientific and Technical Information (OSTI)

    FERMILAB TEVATRON; INTERMEDIATE BOSONS; LEPTONS; LUMINOSITY; MATRIX ELEMENTS; NEURAL NETWORKS; QUARKS; RESOLUTION; T QUARKS Experiment-HEP Word Cloud More Like This Full Text ...

  11. Chromodynamic fluctuations in quark-gluon plasma

    SciTech Connect (OSTI)

    Mrowczynski, Stanislaw

    2008-05-15

    Fluctuations of chromodynamic fields in the collisionless quark-gluon plasma are found as a solution of the initial value linearized problem. The plasma initial state is on average colorless, stationary, and homogeneous. When the state is stable, the initial fluctuations decay exponentially and in the long-time limit a stationary spectrum of fluctuations is established. For the equilibrium plasma it reproduces the spectrum which is provided by the fluctuation-dissipation relation. Fluctuations in the unstable plasma, where the memory of initial fluctuations is not lost, are also discussed.

  12. Quark masses, the Dashen phase, and gauge field topology

    SciTech Connect (OSTI)

    Creutz, Michael

    2013-12-15

    The CP violating Dashen phase in QCD is predicted by chiral perturbation theory to occur when the updown quark mass difference becomes sufficiently large at fixed down-quark mass. Before reaching this phase, all physical hadronic masses and scattering amplitudes are expected to behave smoothly with the up-quark mass, even as this mass passes through zero. In Euclidean space, the topological susceptibility of the gauge fields is positive at positive quark masses but diverges to negative infinity as the Dashen phase is approached. A zero in this susceptibility provides a tentative signal for the point where the mass of the up quark vanishes. I discuss potential ambiguities with this determination. -- Highlights: The CP violating Dashen phase in QCD occurs when the up quark mass becomes sufficiently negative. Before reaching this phase, all physical hadronic masses and scattering amplitudes behave smoothly with the up-quark mass. The topological susceptibility of the gauge fields diverges to negative infinity as the Dashen phase is approached. A zero in the topological susceptibility provides a tentative signal for the point where the mass of the up quark vanishes. The universality of this definition remains unproven. Potential ambiguities are discussed.

  13. Basic features of the pion valence-quark distribution function

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chang, Lei; Mezrag, Cdric; Moutarde, Herv; Roberts, Craig D.; Rodrguez-Quintero, Jose; Tandy, Peter C.

    2014-10-07

    The impulse-approximation expression used hitherto to define the pion's valence-quark distribution function is flawed because it omits contributions from the gluons which bind quarks into the pion. A corrected leading-order expression produces the model-independent result that quarks dressed via the rainbowladder truncation, or any practical analogue, carry all the pion's light-front momentum at a characteristic hadronic scale. Corrections to the leading contribution may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea-quarks. Working with available empirical information, we use an algebraic model to express the principal impact of both classes of corrections. This enables amorerealistic comparison with experiment that allows us to highlight the basic features of the pion's measurable valence-quark distribution, q?(x); namely, at a characteristic hadronic scale, q?(x)~(1-x)2 for x?0.85; and the valence-quarks carry approximately two-thirds of the pion's light-front momentum.less

  14. S-wave QQqq state in the constituent quark model

    SciTech Connect (OSTI)

    Yang Youchang; Deng Chengrong; Ping Jialun; Goldman, T.

    2009-12-01

    Many proposals have been put forward to explore four-quark states QQqq (Q=s, c, b; q=u, d) by experiment, so a systematic study of QQqq spectrum with different constituent quark models by a high precision, few-body method, the Gaussian expression method, is useful. Three quark models: the Bhaduri, Cohler, Nogami quark model, the chiral quark model (ChQM), and the quark delocalization color screening model are all employed for a systematic calculation of the S-wave QQqq spectrum with different color structures, using the Gaussian expression method. The results show that only the bbqq state with (I,J)=(0,1) is bound in different color structures within the different quark models. The binding energy varies from several MeV for a di-meson structure to over 100 MeV for a diquark-antidiquark structure. For the ccqq system, the state with (I,J)=(0,1) is bound in a di-meson structure, and also bound in a diquark-antidiquark structure if pseudoscalar meson exchanges are accounted for. All are weakly bound states. The mixture of diquark-antidiquark and molecular structures is discussed in the framework of quark models for the first time; ccqq with (I,J)=(0,1) is below the threshold in addition to bbqq in both the ChQM and the Bhaduri, Cohler, Nogami quark model. In the same channel, ssqq is also a possible bound state with mass around 1.4 GeV in ChQM.

  15. Theory of hadronic production of heavy quarks

    SciTech Connect (OSTI)

    Peterson, C.

    1981-07-01

    Conventional theoretical predictions for hadronic production of heavy quarks (Q anti Q) are reviewed and confronted with data. Perturbative hard scattering predictions agree qualitatively well with hidden Q anti Q production (e.g., psi, chi, T) whereas for open Q anti Q-production (e.g., pp ..-->.. ..lambda../sub c//sup +/X) additional mechanisms or inputs are needed to explain the forwardly produced ..lambda../sub c//sup +/ at ISR. It is suggested that the presence of c anti c-pairs on the 1 to 2% level in the hadron Fock state decomposition (intrinsic charm) gives a natural description of the ISR data. The theoretical foundations of the intrinsic charm hypotheses together with its consequences for lepton-induced reactions is discussed in some detail.

  16. CSC/UND Team 3 | Open Energy Information

    Open Energy Info (EERE)

    CSCUND Team 3 < CSC Jump to: navigation, search Geothermal Case Study Challenge Geothermal CSC About Judging Schedule Areas How To Sign Up Connect UND Team 3 Team Info School:...

  17. CSC/UND Team 2 | Open Energy Information

    Open Energy Info (EERE)

    CSCUND Team 2 < CSC Jump to: navigation, search Geothermal Case Study Challenge Geothermal CSC About Judging Schedule Areas How To Sign Up Connect UND Team 2 Team Info School:...

  18. ELBE Betreuungs und Verwaltungsgesellschaft mbH | Open Energy...

    Open Energy Info (EERE)

    Betreuungs- und Verwaltungsgesellschaft mbH Place: Germany Product: Company created for tax purposes by M. Denker and M. Wulf to manages their shares in RE-Power References: ELBE...

  19. Quarkonium in a weakly-coupled quark-gluon plasma

    SciTech Connect (OSTI)

    Vairo, Antonio

    2010-12-22

    We report about a recent calculation of the heavy quarkonium mass and decay width in a quark-gluon plasma, whose temperature T and screening mass m{sub D} satisfy the hierarchy m{alpha}{sub s}>>T>>m{alpha}{sub s}{sup 2}>>m{sub D}, m being the heavy-quark mass, up to order m{alpha}{sub s}{sup 5}. The calculation may be relevant to understand the behavior of the {Upsilon}(1S) in a quark-gluon plasma at present-day colliders.

  20. Neutrons and Quarks Share Dual Nature | Jefferson Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Neutrons and Quarks Share Dual Nature Neutrons and Quarks Share Dual Nature Mosiac Title Mosiac Title: No1 beginnning, click for copyright information. When you stand back to admire a mosaic, such as the one to the left, you see the overall image. But look closely, and you can see the individual tiles and binding mortar that make up the mosaic. Physicists do much the same thing when they study protons and neutrons. Crack open a proton or a neutron, and you'll find quarks swarming around inside.

  1. B-Bbar Mixing and Matching with Fermilab Heavy Quarks

    SciTech Connect (OSTI)

    Evans, Richard Todd; Gamiz, Elvira; El-Khadra, Aida; Kronfeld, Andreas; /Fermilab

    2009-11-01

    We discuss the matching procedure for heavy-light 4-quark operators using the Fermilab method for heavy quarks and staggered fermions for light quarks. These ingredients enable us to construct the continuum-limit operator needed to determine the oscillation frequency of neutral B mesons. The matching is then carried out at the one-loop level. We also present an updated preliminary result for the SU(3)-breaking ratio {zeta}, based on calculations using the MILC Collaboration's ensembles of lattice gauge fields.

  2. Top quark production and properties at the Tevatron

    SciTech Connect (OSTI)

    Fiedler, Frank; /Munich U.

    2005-06-01

    The precise measurement of top quark production and properties is one of the primary goals of the Tevatron during Run II. The total t{bar t} production cross-section has been measured in a large variety of decay channels and using different selection criteria. Results from differential cross-section measurements and searches for new physics in t{bar t} production and top quark decays are available. Electroweak production of single top quarks has been searched for. The results from all these analyses, using typically 200 pb{sup -1} of data, are presented.

  3. Top quark and SUSY (supersymmetric) searches at CDF

    SciTech Connect (OSTI)

    Yeh, G.P.

    1990-05-17

    Searches for the top quark in p{bar p} collisions at {radical}s = 1.8 TeV are described. The analyses are based on data with an integrated luminosity of 4.4 pb{sup {minus}1} recorded with the Collider Detector at Fermilab in the 1988--1989 run. An upper limit on the t{bar t} cross section is obtained. The top quark with mass below 89 GeV/c{sup 2} is excluded at the 95% CL. Prospects for searches for the top quark in the future are presented. We also briefly present results on searches for supersymmetric particles. 14 refs., 10 figs.

  4. G-Zero Finds that Ghostly Strange Quarks Influence Proton Structure |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Jefferson Lab G-Zero Finds that Ghostly Strange Quarks Influence Proton Structure G-Zero Finds that Ghostly Strange Quarks Influence Proton Structure June 17, 2005 In research performed at the Department of Energy's Jefferson Lab, nuclear physicists have found that strange quarks do contribute to the structure of the proton. This result indicates that, just as previous experiments have hinted, strange quarks in the proton's quark-gluon sea contribute to a proton's properties. The result

  5. 2013 JSA Postdoctoral Research Grant Winner to Compute Quarks...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    3 JSA Postdoctoral Research Grant Winner to Compute Quarks Chris Monahan Chris Monahan ... Monahan is the recipient of the 2013 JSA Postdoctoral Research Grant at the U.S. ...

  6. The top quark, 20 years after its discovery

    SciTech Connect (OSTI)

    Denisov, Dmitri; Vellidis, Costas

    2015-04-15

    The heaviest of nature’s elementary particles plays an outsized role in many fundamental processes. But because the top quark is so massive, it eluded experimental detection for nearly two decades.

  7. Quark mass functions and pion structure in Minkowski space

    SciTech Connect (OSTI)

    Biernat, Elmer P.; Gross, Franz L.; Pena, Maria Teresa; Stadler, Alfred

    2014-03-01

    We present a study of the dressed quark mass function and the pion structure in Minkowski space using the Covariant Spectator Theory (CST). The quark propagators are dressed with the same kernel that describes the interaction between different quarks. We use an interaction kernel in momentum space that is a relativistic generalization of the linear confining q-qbar potential and a constant potential shift that defines the energy scale. The confining interaction has a Lorentz scalar part that is not chirally invariant by itself but decouples from the equations in the chiral limit and therefore allows the Nambu--Jona-Lasinio (NJL) mechanism to work. We adjust the parameters of our quark mass function calculated in Minkowski-space to agree with LQCD data obtained in Euclidean space. Results of a calculation of the pion electromagnetic form factor in the relativistic impulse approximation using the same mass function are presented and compared with experimental data.

  8. Evidence for electroweak top quark production in proton-antiproton...

    Office of Scientific and Technical Information (OSTI)

    acceptance, background, and observed data we measure the single top quark cross section: sigma(pbar p yields tb + tqb + X) 4.6sub -1.5sup +1.8 pb. The probability for...

  9. Fermilab | Newsroom | Press Releases | September 27, 2012: QuarkNet...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    RELEASE QuarkNet program receives 6.1 million NSF award to advance science education Hi-res | Med-res Steven Grosland, physics teacher at Glenbrook South High School in...

  10. Observation of $t$-channel electroweak top quark production

    SciTech Connect (OSTI)

    Triplett, Nathan; /Iowa State U.

    2011-04-01

    The top quark is the heaviest known fundamental particle, with a mass of 172.0{sub -1.3}{sup +0.9}GeV. This is nearly twice the mass of the second heaviest known particle, the Z boson, and roughly the mass of a gold atom. Because of its unusually large mass, studying the top quark may provide insight into the Higgs mechanism and other beyond the standard model physics. Only two accelerators in the world are powerful enough to produce top quarks. The Tevatron, which first accelerated protons in 1983, has produced almost 400,000 top quarks, roughly half at each of its two detectors: DO and CDF. The LHC is a much newer accelerator which currently has accumulated about 0.5% as much data as the Tevatron. However, when running at full luminosity, the LHC is capable of producing a top quark about once every second and will quickly surpass the Tevatron as the leading producer of top quarks. This analysis uses data from the D0 detector at the Tevatron, which are described in chapter 3. Top quarks are produced most often in pairs of top and anti-top quarks through an interaction of the strong force. This production mode was first observed in 1995 at the Tevatron. However, top quarks can also be produced though an electroweak interaction, which produces just one top quark. This production mode was first observed at the Tevatron in 2008. Single top quark production can occur in different channels. In this analysis, a measurement of the cross section of the t-channel production mode is performed. This measurement uses 5.4 fb{sup -1} of data and uses the technique of boosted decision trees in order to separate signal from background events. The t-channel cross section is measured to be: {sigma}(p{bar p} {yields} tqb + X) = 3.03{sub -0.66}{sup +0.78}pb (0.0.1). Additional cross section measurements were also performed for the s-channel as well as the s + t-channel. The measurement of each one of these three cross sections was repeated three times using different techniques, and all three methods were combined into a 'super-method' which achieves the best performance. The details of these additional measurements are shown in appendix A.

  11. The top quark (20 years after the discovery)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Boos, Eduard; Brandt, Oleg; Denisov, Dmitri; Denisov, Sergey; Grannis, Paul

    2015-09-10

    On the twentieth anniversary of the observation of the top quark, we trace our understanding of this heaviest of all known particles from the prediction of its existence, through the searches and discovery, to the current knowledge of its production mechanisms and properties. We also discuss the central role of the top quark in the Standard Model and the windows that it opens for seeking new physics beyond the Standard Model.

  12. MARTINI event generator for heavy quarks: Initialization, parton evolution,

    Office of Scientific and Technical Information (OSTI)

    and hadronization (Journal Article) | DOE PAGES MARTINI event generator for heavy quarks: Initialization, parton evolution, and hadronization « Prev Next » Title: MARTINI event generator for heavy quarks: Initialization, parton evolution, and hadronization Authors: Young, Clint ; Schenke, Björn ; Jeon, Sangyong ; Gale, Charles Publication Date: 2012-09-10 OSTI Identifier: 1103304 Type: Publisher's Accepted Manuscript Journal Name: Physical Review C Additional Journal Information: Journal

  13. Reconstructing top quark-antiquark events with one lost jet

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Demina, Regina; Harel, Amnon; Orbaker, Douglas

    2015-04-02

    We present a technique for reconstructing the kinematics of pair-produced top quarks that decay to a charged lepton, a neutrino and four final state quarks in the subset of events where only three jets are reconstructed. We present a figure of merit that allows for a fair comparison of reconstruction algorithms without requiring their calibration. The new reconstruction of events with only three jets is fully competitive with the full reconstruction typically used for four-jet events.

  14. Erratum: Chiral transition and mesonic excitations for quarks with thermal

    Office of Scientific and Technical Information (OSTI)

    masses [Phys. Rev. D 75, 011901 (2007)] (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Erratum: Chiral transition and mesonic excitations for quarks with thermal masses [Phys. Rev. D 75, 011901 (2007)] Citation Details In-Document Search Title: Erratum: Chiral transition and mesonic excitations for quarks with thermal masses [Phys. Rev. D 75, 011901 (2007)] No abstract prepared. Authors: Hidaka, Yoshimasa ; Kitazawa, Masakiyo Publication Date: 2007-05-01

  15. MARTINI event generator for heavy quarks: Initialization, parton evolution,

    Office of Scientific and Technical Information (OSTI)

    and hadronization (Journal Article) | SciTech Connect MARTINI event generator for heavy quarks: Initialization, parton evolution, and hadronization Citation Details In-Document Search Title: MARTINI event generator for heavy quarks: Initialization, parton evolution, and hadronization Authors: Young, Clint ; Schenke, Björn ; Jeon, Sangyong ; Gale, Charles Publication Date: 2012-09-10 OSTI Identifier: 1103304 Type: Publisher's Accepted Manuscript Journal Name: Physical Review C Additional

  16. Quark mass variation constraints from Big Bang nucleosynthesis (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Quark mass variation constraints from Big Bang nucleosynthesis Citation Details In-Document Search Title: Quark mass variation constraints from Big Bang nucleosynthesis × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and Technical Information (OSTI) and is provided as a public service. Visit OSTI to utilize additional information resources in energy science and technology. A

  17. Top Quark Anomalous Couplings at the International Linear Collider (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Top Quark Anomalous Couplings at the International Linear Collider Citation Details In-Document Search Title: Top Quark Anomalous Couplings at the International Linear Collider × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and Technical Information (OSTI) and is provided as a public service. Visit OSTI to utilize additional information resources in energy science and

  18. Top quark anomalous couplings at the International Linear Collider (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect quark anomalous couplings at the International Linear Collider Citation Details In-Document Search Title: Top quark anomalous couplings at the International Linear Collider Authors: Devetak, Erik ; Nomerotski, Andrei ; Peskin, Michael Publication Date: 2011-08-17 OSTI Identifier: 1100572 Type: Publisher's Accepted Manuscript Journal Name: Physical Review D Additional Journal Information: Journal Volume: 84; Journal Issue: 3; Journal ID: ISSN 1550-7998 Publisher:

  19. Dark matter and dark energy from quark bag model

    SciTech Connect (OSTI)

    Brilenkov, Maxim; Eingorn, Maxim; Jenkovszky, Laszlo; Zhuk, Alexander E-mail: maxim.eingorn@gmail.com E-mail: ai.zhuk2@gmail.com

    2013-08-01

    We calculate the present expansion of our Universe endowed with relict colored objects quarks and gluons that survived hadronization either as isolated islands of quark-gluon ''nuggets'' or spread uniformly in the Universe. In the first scenario, the QNs can play the role of dark matter. In the second scenario, we demonstrate that uniform colored objects can play the role of dark energy providing the late-time accelerating expansion of the Universe.

  20. Anomalies of quark diagrams in the decay eta. --> pi. /sup 0/. gamma gamma. and the quark structure of the scalar meson delta(980)

    SciTech Connect (OSTI)

    Ivanov, A.N.; Troitskaya, N.I.

    1982-08-01

    The width of the decay eta..--> pi../sup 0/..gamma gamma.. is calculated in the model of dominance of quark loop anomalies. We investigate the contribution of the scalar meson delta(980) for two versions of its quark structure: a) the delta meson is a /sup 2/P/sub 0/ state of a quark-antiquark pair, b) the delta meson is a quark molecule of the type qqqq. We discuss the results.

  1. Shell Solar GmbH formerly Siemens und Shell Solar GmbH | Open...

    Open Energy Info (EERE)

    GmbH formerly Siemens und Shell Solar GmbH Jump to: navigation, search Name: Shell Solar GmbH (formerly Siemens und Shell Solar GmbH) Place: Munich, Bavaria, Germany Zip: 80807...

  2. Paradigma Energie und Umwelttechnik GmbH Co KG | Open Energy...

    Open Energy Info (EERE)

    Paradigma Energie und Umwelttechnik GmbH Co KG Jump to: navigation, search Name: Paradigma Energie- und Umwelttechnik GmbH & Co KG Place: Karlsbad, Germany Zip: 76307 Sector: Solar...

  3. Geothermie Unterhaching GmbH und Co KG | Open Energy Information

    Open Energy Info (EERE)

    Geothermie Unterhaching GmbH und Co KG Jump to: navigation, search Name: Geothermie Unterhaching GmbH und Co KG Place: Unterhaching, Bavaria, Germany Zip: 82008 Sector: Geothermal...

  4. Constituent quark scaling violation due to baryon number transport

    SciTech Connect (OSTI)

    Dunlop J. C.; Lisa, M.A., Sorensen, P.

    2011-10-31

    In ultrarelativistic heavy-ion collisions at {radical}s{sub NN} {approx} 200 GeV, the azimuthal emission anisotropy of hadrons with low and intermediate transverse momentum (p{sub T} {approx}< 4 GeV/c) displays an intriguing scaling. In particular, the baryon (meson) emission patterns are consistent with a scenario in which a bulk medium of flowing quarks coalesces into three-quark (two-quark) 'bags.' While a full understanding of this number-of-constituent-quark (NCQ) scaling remains elusive, it is suggestive of a thermalized bulk system characterized by colored dynamical degrees of freedom - a quark-gluon plasma (QGP). In this scenario, one expects the scaling to break down as the central energy density is reduced below the QGP formation threshold; for this reason, NCQ-scaling violation searches are of interest in the energy scan program at the Relativistic Heavy Ion Collider. However, as {radical}s{sub NN} is reduced, it is not only the initial energy density that changes; there is also an increase in the net baryon number at midrapidity, as stopping transports entrance-channel partons to midrapidity. This phenomenon can result in violations of simple NCQ scaling. Still in the context of the quark coalescence model, we describe a specific pattern for the breakdown of the scaling that includes different flow strengths for particles and their antipartners. Related complications in the search for recently suggested exotic phenomena are also discussed.

  5. Jet conversions in a quark-gluon plasma

    SciTech Connect (OSTI)

    Liu, W.; Ko, C. M.; Zhang, B. W.

    2007-05-15

    Quark and gluon jets traversing through a quark-gluon plasma not only lose their energies but also can undergo flavor conversions. The conversion rates via the elastic q(q)g{yields}gq(q) and the inelastic qq{r_reversible}gg scatterings are evaluated in the lowest order in QCD. Including both jet energy loss and conversions in the expanding quark-gluon plasma produced in relativistic heavy ion collisions, we have found a net of quark jets to gluon jets. This reduces the difference between the nuclear modification factors for quark and gluon jets in central heavy ion collisions and thus enhances the p/{pi}{sup +} and p/{pi}{sup -} ratios at high transverse momentum. However, a much larger net quark-to-gluon jet conversion rate than the one given by the lowest order QCD is needed to account for the observed similar ratios in central Au+Au and p+p collisions at the same energy. Implications of our results are discussed.

  6. Improved determination of the width of the top quark

    SciTech Connect (OSTI)

    Abazov V. M.; Abbott B.; Acharya B. S.; Adams M.; Adams T.; Alexeev G. D.; Alkhazov G.; Alton A.; Alverson G.; Aoki M.; Askew A.; Asman B.; Atkins S.; Atramentov O.; Augsten K.; Avila C.; BackusMayes J.; Badaud F.; Bagby L.; Baldin B.; Bandurin D. V.; Banerjee S.; Barberis E.; Baringer P.; Barreto J.; Bartlett J. F.; Bassler U.; Bazterra V.; Bean A.; Begalli M.; Belanger-Champagne C.; Bellantoni L.; Beri S. B.; Bernardi G.; Bernhard R.; Bertram I.; Besancon M.; Beuselinck R.; Bezzubov V. A.; Bhat P. C.; Bhatia S.; Bhatnagar V.; Blazey G.; Blessing S.; Bloom K.; Boehnlein A.; Boline D.; Boos E. E.; Borissov G.; Bose T.; Brandt A.; Brandt O.; Brock R.; Brooijmans G.; Bross A.; Brown D.; Brown J.; Bu X. B.; Buehler M.; Buescher V.; Bunichev V.; Burdin S.; Burnett T. H.; Buszello C. P.; Calpas B.; Camacho-Perez E.; Carrasco-Lizarraga M. A.; Casey C. K.; Castilla-Valdez H.; Chakrabarti S.; Chakraborty D.; Chan M.; Chandra A.; Chapon E.; Chen G.; Chevalier-Thery S.; Cho D. K.; Cho S. W.; Choi S.; Choudhary B.; Cihangir S.; Claes D.; Clutter J.; Cooke M.; Cooper W. E.; Corcoran M.; Couderc F.; Cousinou M. -C.; Croc A.; Cutts D.; Das A.; Davies G.; de Jong S. J.; De La Cruz-Burelo E.; Deliot F.; Demina R.; Denisov D.; Denisov S. P.; Desai S.; Deterre C.; DeVaughan K.; Diehl H. T.; Diesburg M.; Ding P. F.; Dominguez A.; Dorland T.; Dubey A.; Dudko L. V.; Duggan D.; Duperrin A.; Dutt S.; Dyshkant A.; Eads M.; Edmunds D.; Ellison J.; Elvira V. D.; Enari Y.; Evans H.; Evdokimov A.; Evdokimov V. N.; Facini G.; Ferbel T.; Fiedler F.; Filthaut F.; Fisher W.; Fisk H. E.; Fortner M.; Fox H.; Fuess S.; Garcia-Bellido A.; Garcia-Guerra G. A.; Gavrilov V.; Gay P.; Geng W.; Gerbaudo D.; Gerber C. E.; Gershtein Y.; Ginther G.; Golovanov G.; Goussiou A.; Graf C. P.; Grannis P. D.; Greder S.; Greenlee H.; Greenwood Z. D.; Gregores E. M.; Grenier G.; Gris Ph.; Grivaz J. -F.; Grohsjean A.; Gruenendahl S.; Gruenewald M. W.; Guillemin T.; Gutierrez G.; Gutierrez P.; Haas A.; Hagopian S.; Haley J.; Han L.; Harder K.; Harel A.; Hauptman J. M.; Hays J.; Head T.; Hebbeker T.; Hedin D.; Hegab H.; Heinson A. P.; Heintz U.; Hensel C.; La Cruz I. Heredia-De; Herner K.; Hesketh G.; Hildreth M. D.; Hirosky R.; Hoang T.; Hobbs J. D.; Hoeneisen B.; Hohlfeld M.; Hubacek Z.; Hynek V.; Iashvili I.; Ilchenko Y.; Illingworth R.; Ito A. S.; Jabeen S.; Jaffre M.; Jamin D.; Jayasinghe A.; Jesik R.; Johns K.; Johnson M.; Jonckheere A.; Jonsson P.; Joshi J.; Jung A. W.; Juste A.; Kaadze K.; Kajfasz E.; Karmanov D.; Kasper P. A.; Katsanos I.; Kehoe R.; Kermiche S.; Khalatyan N.; Khanov A.; Kharchilava A.; Kharzheev Y. N.; Kohli J. M.; Kozelov A. V.; Kraus J.; Kulikov S.; Kumar A.; Kupco A.; Kurca T.; Kuzmin V. A.; Lammers S.; Landsberg G.; Lebrun P.; Lee H. S.; Lee S. W.; Lee W. M.; Lellouch J.; Li H.; Li L.; Li Q. Z.; Lietti S. M.; Lim J. K.; Lincoln D.; Linnemann J.; Lipaev V. V.; Lipton R.; Liu Y.; Lobodenko A.; Lokajicek M.; de Sa R. Lopes; Lubatti H. J.; Luna-Garcia R.; Lyon A. L.; Maciel A. K. A.; Mackin D.; Madar R.; Magana-Villalba R.; Malik S.; Malyshev V. L.; Maravin Y.; Martinez-Ortega J.; McCarthy R.; McGivern C. L.; Meijer M. M.; Melnitchouk A.; Menezes D.; Mercadante P. G.; Merkin M.; et al.

    2012-05-04

    We present an improved determination of the total width of the top quark, {Gamma}{sub t}, using 5.4 fb{sup -1} of integrated luminosity collected by the D0 Collaboration at the Tevatron p{bar p} Collider. The total width {Gamma}{sub t} is extracted from the partial decay width {Gamma}(t {yields} Wb) and the branching fraction {Beta}(t {yields} Wb). {Gamma}(t {yields} Wb) is obtained from the t-channel single top-quark production cross section and {Beta}(t {yields} Wb) is measured in t{bar t} events. For a top mass of 172.5 GeV, the resulting width is {Gamma}{sub t} = 2.00{sub -0.43}{sup +0.47} GeV. This translates to a top-quark lifetime of {tau}{sub t} = (3.29{sub -0.63}{sup +0.90}) x 10{sup -25} s. We also extract an improved direct limit on the Cabibbo-Kobayashi-Maskawa quark-mixing matrix element 0.81 < |V{sub tb}| {le} 1 at 95% C.L. and a limit of |V{sub tb}| < 0.59 for a high-mass fourth-generation bottom quark assuming unitarity of the fourth-generation quark-mixing matrix.

  7. Big Bang Day: 5 Particles - 2. The Quark

    SciTech Connect (OSTI)

    None

    2009-10-07

    Simon Singh looks at the stories behind the discovery of 5 of the universe's most significant subatomic particles: the Electron, the Quark, the Anti-particle, the Neutrino and the "next particle". 2. The Quark "Three Quarks for Master Mark! Sure he hasn't got much of a bark." James Joyce's Finnegans Wake left its mark on modern physics when physicist Murray Gell Mann proposed this name for a group of hypothetical subatomic particles that were revealed in 1960 as the fundamental units of matter. Basic particles it seems are made up of even more basic units called quarks that make up 99.9% of visible material in the universe.. But why do we know so little about them? Quarks have never been seen as free particles but instead, inextricably bound together by the Strong Force that in turn holds the atomic nucleus together. This is the hardest of Nature's fundamental forces to crack, but recent theoretical advances, mean that the properties of the quark are at last being revealed.

  8. Big Bang Day: 5 Particles - 2. The Quark

    ScienceCinema (OSTI)

    None

    2011-04-25

    Simon Singh looks at the stories behind the discovery of 5 of the universe's most significant subatomic particles: the Electron, the Quark, the Anti-particle, the Neutrino and the "next particle". 2. The Quark "Three Quarks for Master Mark! Sure he hasn't got much of a bark." James Joyce's Finnegans Wake left its mark on modern physics when physicist Murray Gell Mann proposed this name for a group of hypothetical subatomic particles that were revealed in 1960 as the fundamental units of matter. Basic particles it seems are made up of even more basic units called quarks that make up 99.9% of visible material in the universe.. But why do we know so little about them? Quarks have never been seen as free particles but instead, inextricably bound together by the Strong Force that in turn holds the atomic nucleus together. This is the hardest of Nature's fundamental forces to crack, but recent theoretical advances, mean that the properties of the quark are at last being revealed.

  9. Top quark mass measurement using the template method at CDF

    SciTech Connect (OSTI)

    Aaltonen, T; Alvarez Gonzalez, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Apresyan, A; Arisawa, T

    2011-06-03

    We present a measurement of the top quark mass in the lepton+jets and dilepton channels of tt? decays using the template method. The data sample corresponds to an integrated luminosity of 5.6 fb-1 of pp? collisions at Tevatron with ?s = 1.96 TeV, collected with the CDF II detector. The measurement is performed by constructing templates of three kinematic variables in the lepton+jets and two kinematic variables in the dilepton channel. The variables are two reconstructed top quark masses from different jets-to-quarks combinations and the invariant mass of two jets from the W decay in the lepton+jets channel, and a reconstructed top quark mass and mT2, a variable related to the transverse mass in events with two missing particles, in the dilepton channel. The simultaneous fit of the templates from signal and background events in the lepton+jets and dilepton channels to the data yields a measured top quark mass of Mtop = 172.11.1 (stat)0.9 (syst) GeV/c2.

  10. Sketching the pion's valence-quark generalised parton distribution

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mezrag, C.; Chang, L.; Moutarde, H.; Roberts, C. D.; Rodrguez-Quintero, J.; Sabati, F.; Schmidt, S. M.

    2015-02-01

    In order to learn effectively from measurements of generalised parton distributions (GPDs), it is desirable to compute them using a framework that can potentially connect empirical information with basic features of the Standard Model. We sketch an approach to such computations, based upon a rainbow-ladder (RL) truncation of QCDs DysonSchwinger equations and exemplified via the pions valence dressed-quark GPD, Hv?(x, ?, t). Our analysis focuses primarily on ?=0, although we also capitalise on the symmetry-preserving nature of the RL truncation by connecting Hv?(x, ?=1, t)with the pions valence-quark parton distribution amplitude. We explain that the impulse-approximation used hitherto to definemorethe pions valence dressed-quark GPD is generally invalid owing to omission of contributions from the gluons which bind dressed-quarks into the pion. A simple correction enables us to identify a practicable improvement to the approximation for Hv?(x, 0, t), expressed as the Radon transform of a single amplitude. Therewith we obtain results for Hv?(x, 0, t) and the associated impact-parameter dependent distribution, qv?(x, |b?|), which provide a qualitatively sound picture of the pions dressed-quark structure at a hadronic scale. We evolve the distributions to a scale ? = 2 GeV, so as to facilitate comparisons in future with results from experiment or other nonperturbative methods.less

  11. Search for baryon number violation in top-quark decays

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chatrchyan, Serguei

    2014-02-20

    A search for baryon number violation (BNV) in top-quark decays is performed using pp collisions produced by the LHC at sqrt(s) = 8 TeV. The top-quark decay considered in this search results in one light lepton (muon or electron), two jets, but no neutrino in the final state. Data used for the analysis were collected by the CMS detector and correspond to an integrated luminosity of 19.5 inverse femtobarns. The event selection is optimized for top quarks produced in pairs, with one undergoing the BNV decay and the other the standard model hadronic decay to three jets. No significant excessmore » of events over the expected yield from standard model processes is observed. The upper limits at 95% confidence level on the branching fraction of the BNV top-quark decay are calculated to be 0.0016 and 0.0017 for the muon and the electron channels, respectively. Assuming lepton universality, an upper limit of 0.0015 results from the combination of the two channels. These limits are the first that have been obtained on a BNV process involving the top quark.« less

  12. Top quark mass measurement using the template method at CDF

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T

    2011-06-03

    We present a measurement of the top quark mass in the lepton+jets and dilepton channels of tmore » $$\\bar{t}$$ decays using the template method. The data sample corresponds to an integrated luminosity of 5.6 fb-1 of p$$\\bar{p}$$ collisions at Tevatron with √s = 1.96 TeV, collected with the CDF II detector. The measurement is performed by constructing templates of three kinematic variables in the lepton+jets and two kinematic variables in the dilepton channel. The variables are two reconstructed top quark masses from different jets-to-quarks combinations and the invariant mass of two jets from the W decay in the lepton+jets channel, and a reconstructed top quark mass and mT2, a variable related to the transverse mass in events with two missing particles, in the dilepton channel. The simultaneous fit of the templates from signal and background events in the lepton+jets and dilepton channels to the data yields a measured top quark mass of Mtop = 172.1±1.1 (stat)±0.9 (syst) GeV/c2.« less

  13. Recent Results in the Top Quark Sector from the D0 Experiment...

    Office of Scientific and Technical Information (OSTI)

    Recent Results in the Top Quark Sector from the D0 Experiment Citation Details In-Document Search Title: Recent Results in the Top Quark Sector from the D0 Experiment You are ...

  14. Electroweak production of top-quark pairs in e+e- annihilation...

    Office of Scientific and Technical Information (OSTI)

    production of top-quark pairs in e+e- annihilation at NNLO in QCD: The vector current contributions Citation Details In-Document Search Title: Electroweak production of top-quark ...

  15. Photon emission from a momentum-anisotropic quark-gluon plasma...

    Office of Scientific and Technical Information (OSTI)

    Photon emission from a momentum-anisotropic quark-gluon plasma Prev Next Title: Photon emission from a momentum-anisotropic quark-gluon plasma Authors: Shen, Chun ; Paquet, ...

  16. Anisotropic flow of thermal photons as a quark-gluon plasma viscometer...

    Office of Scientific and Technical Information (OSTI)

    Anisotropic flow of thermal photons as a quark-gluon plasma viscometer Prev Next Title: Anisotropic flow of thermal photons as a quark-gluon plasma viscometer Authors: Shen, Chun ...

  17. Photon emission from a momentum-anisotropic quark-gluon plasma...

    Office of Scientific and Technical Information (OSTI)

    Photon emission from a momentum-anisotropic quark-gluon plasma Citation Details In-Document Search Title: Photon emission from a momentum-anisotropic quark-gluon plasma Authors: ...

  18. Pion cloud and sea quark flavor asymmetry in the impact parameter...

    Office of Scientific and Technical Information (OSTI)

    Pion cloud and sea quark flavor asymmetry in the impact parameter representation Citation Details In-Document Search Title: Pion cloud and sea quark flavor asymmetry in the impact ...

  19. INTERACTING QUARK MATTER EQUATION OF STATE FOR COMPACT STARS

    SciTech Connect (OSTI)

    Fraga, Eduardo S.; Kurkela, Aleksi; Vuorinen, Aleksi

    2014-02-01

    Lattice quantum chromodynamics (QCD) studies of the thermodynamics of hot quark-gluon plasma demonstrate the importance of accounting for the interactions of quarks and gluons if one wants to investigate the phase structure of strongly interacting matter. Motivated by this observation and using state-of-the-art results from perturbative QCD, we construct a simple, effective equation of state (EOS) for cold quark matter that consistently incorporates the effects of interactions and furthermore includes a built-in estimate of the inherent systematic uncertainties. This goes beyond the MIT bag model description in a crucial way, yet leads to an EOS that is equally straightforward to use. We also demonstrate that, at moderate densities, our EOS can be made to smoothly connect to hadronic EOSs, with the two exhibiting very similar behavior near the matching region. The resulting hybrid stars are seen to have masses similar to those predicted by the purely nucleonic EOSs.

  20. Nucleation of quark matter in the PQM model

    SciTech Connect (OSTI)

    Mintz, Bruno W.; Stiele, Rainer; Schaffner-Bielich, Juergen; Ramos, Rudnei O.

    2013-03-25

    We use Langer's theory to calculate the surface tension of critical bubbles in a first-order quark-hadron phase transition at moderate and high baryon chemical potential, as predicted by the Polyakov-Quark-Meson (PQM) model at the mean-field level. We define an effective 4-dimensional order parameter, which is used to overestimate the surface tension of nucleating bubbles within the thin-wall approximation. We find relatively low values for the surface tension, {Sigma} Less-Than-Or-Equivalent-To 15MeV/fm{sup 2}. This implies that a metastable state, such as a supercooled quark-gluon plasma (QGP), quickly decays even in regions relatively close to the coexistence line of the phase diagram. Possible consequences for cosmology are briefly outlined.

  1. Neural Networks for Analysis of Top Quark Production

    SciTech Connect (OSTI)

    B. Abbott et al.

    1999-08-04

    Neural networks (NNs) provide a powerful and flexible tool for selecting a signal from a larger background. The D0 collaboration has used them extensively in studying t{anti t} decays. NNs were essential to the measurement of the t{anti t} production cross section in the all-jets channel (t{anti t} {yields} b {anti b}qqqq), and were also used in the measurement of the mass of the top quark in the lepton+jets channel (t{anti t} {yields} b{anti b}l{nu}q{anti q}). This paper will describe two new applications of neural networks to top quark analysis: the search for single top quark production, and an effort to increase the sensitivity in the dilepton channel t{anti t} {yields} b{anti b}e{anti {mu}}{nu}{anti {nu}} beyond that achieved in the published analysis.

  2. Quark04 Ray Stefanski Title Page A Select (SBL) Overview of Neutrino Experiments.

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Article) | SciTech Connect Journal Article: Quark mass variation constraints from Big Bang nucleosynthesis Citation Details In-Document Search Title: Quark mass variation constraints from Big Bang nucleosynthesis We study the impact on the primordial abundances of light elements created of a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and

  3. Rare {Lambda}{sub b} decays in a quark model

    SciTech Connect (OSTI)

    Mott, L.; Roberts, W.

    2010-08-05

    Hadronic form factors for the rare weak transitions {Lambda}{sub b{yields}{Lambda}}{sup (*)} are calculated using a nonrelativistic quark model. The form factors obtained in this way are found to satisfy the relationships expecetd from the heavy quark effective theory. Differential decay rates and branching ratios are calculated for the dileptonic decays {Lambda}{sub b{yields}{Lambda}}{sup (*)}l{sup +}l{sup -}, for both ground state and excited daughter baryons. Inclusion of the long distance contributions from charmonium resonances significantly enhances the decay rates. Future work is outlined.

  4. Nuclear-matter--quark-matter phase diagram with strangeness

    SciTech Connect (OSTI)

    Barz, H. W.; Friman, B. L.; Knoll, J.; Schulz, H.

    1989-07-01

    A phenomenological equation of state of strongly interacting matter, including strange degrees of freedom, is presented. It is shown that the hyperon and kaon interactions must be included, in order to obtain a reasonable description of the deconfinement transition at high baryon densities. The consequences of kaon condensation on the nuclear-matter--quark-matter phase diagram are explored. The relative particle abundances obtained in an isentropic expansion of a blob of quark-gluon plasma are presented for different initial conditions. Implications for ultrarelativistic heavy-ion collisions are briefly discussed.

  5. Quark-gluon correlations and Color Polarizabilities (Journal Article) |

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Quark-gluon correlations and Color Polarizabilities Citation Details In-Document Search Title: Quark-gluon correlations and Color Polarizabilities We discuss the present status of the twist-3 matrix element in the spin srtructure of the nucleon and describe two proposed experiments that will improve on the precision of the present measurements of the twist-3 and twist-4 matrix elements for both the proton and the neutron and consequently will improve on our knowledge of the

  6. Top Quark Anomalous Couplings at the International Linear Collider (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Quark Anomalous Couplings at the International Linear Collider Citation Details In-Document Search Title: Top Quark Anomalous Couplings at the International Linear Collider We present a study of the experimental determination of the forward-backward asymmetry in the process e{sup +}e{sup -} {yields} t{bar t} and in the subsequent t {yields} Wb decay, studied in the context of the International Linear Collider. This process probes the elementary couplings of the top

  7. Meson properties in a nonlocal SU(3) chiral quark model at finite temperature

    SciTech Connect (OSTI)

    Contrera, G. A.; Gomez Dumm, D.; Scoccola, N. N.

    2010-11-12

    Finite temperature meson properties are studied in the context of a nonlocal SU(3) quark model which includes flavor mixing and the coupling of quarks to the Polyakov loop (PL). We analyze the behavior of scalar and pseudoscalar meson masses and mixing angles, as well as quark-meson couplings and pseudoscalar meson decay constants.

  8. Precision Top-Quark Mass Measurements at CDF

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Arisawa, T.; Artikov, A.; /Dubna, JINR /Texas A-M

    2012-07-01

    We present a precision measurement of the top-quark mass using the full sample of Tevatron {radical}s = 1.96 TeV proton-antiproton collisions collected by the CDF II detector, corresponding to an integrated luminosity of 8.7 fb{sup -1}. Using a sample of t{bar t} candidate events decaying into the lepton+jets channel, we obtain distributions of the top-quark masses and the invariant mass of two jets from the W boson decays from data. We then compare these distributions to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with in situ calibration. The likelihood fit of the templates from signal and background events to the data yields the single most-precise measurement of the top-quark mass, mtop = 172.85 {+-} 0.71 (stat) {+-} 0.85 (syst) GeV/c{sup 2}.

  9. Equation of state and heavy-quark free energy at finite temperature and density in two flavor lattice QCD with Wilson quark action

    SciTech Connect (OSTI)

    Ejiri, S.; Maezawa, Y.; Ukita, N.; Aoki, S.; Hatsuda, T.; Ishii, N.; Kanaya, K.; Umeda, T.

    2010-07-01

    We study the equation of state at finite temperature and density in two-flavor QCD with the renormalization group improved gluon action and the clover-improved Wilson quark action on a 16{sup 3}x4 lattice. Along the lines of constant physics at m{sub PS}/m{sub V}=0.65 and 0.80, we compute the second and forth derivatives of the grand canonical partition function with respect to the quark chemical potential {mu}{sub q}=({mu}{sub u}+{mu}{sub d})/2 and the isospin chemical potential {mu}{sub I}=({mu}{sub u}-{mu}{sub d})/2 at vanishing chemical potentials, and study the behaviors of thermodynamic quantities at finite {mu}{sub q} using these derivatives for the case {mu}{sub I}=0. In particular, we study density fluctuations at nonezero temperature and density by calculating the quark number and isospin susceptibilities and their derivatives with respect to {mu}{sub q}. To suppress statistical fluctuations, we also examine new techniques applicable at low densities. We find a large enhancement in the fluctuation of the quark number when the density increased near the pseudocritical temperature, suggesting a critical point at finite {mu}{sub q} terminating the first order transition line between hadronic and quark-gluon-plasma phases. This result agrees with the previous results using staggered-type quark actions qualitatively. Furthermore, we study heavy-quark free energies and Debye screening masses at finite density by measuring the first and second derivatives of these quantities for various color channels of heavy quark-quark and quark-antiquark pairs. The results suggest that, to the leading order of {mu}{sub q}, the interaction between two quarks becomes stronger at finite densities, while that between quark and antiquark becomes weaker.

  10. BNL-71205-2003-CP THE TOP QUARK, QCD, AND NEW PHYSICS S

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    4, 2003 13:28 WSPC/Trim Size: 9in x Gin for Proceedings tasi02'new BNL-71205-2003-CP THE TOP QUARK, QCD, AND NEW PHYSICS S . DAWSON" Physics Department, Brookhaven National Laboratory, Upton, N Y 11973, USA dawson@bnl .go" The role of the top quark in completing the Standard Model quark sector is re- viewed, along with a discussion of production, decay, and theoretical restrictions on the top quark properties. Particular attention is paid to the top quark as a lab- oratory for

  11. Final Report for Project. Quark matter under extreme conditions

    SciTech Connect (OSTI)

    Incera, Vivian; Ferrer, Efrain

    2015-12-31

    The results obtained in the two years of the grant have served to shine new light on several important questions about the phases of quantum chromodynamics (QCD) under extreme conditions that include quark matter at high density, as well quark-gluon plasma at high temperatures, both in the presence of strong magnetic fields. The interest in including an external magnetic field on these studies is motivated by the generation of large magnetic fields in off-central heavy-ion collisions and by their common presence in astrophysical compact objects, the two scenarios where the physics of quark matter becomes relevant. The tasks carried out in this DOE project led us, among other things, to discover the first connection between the physics of very dense quark matter and novel materials as for instance topological insulators and Weyl semimetals; they allowed us to find a physical explanation for and a solution to a standing puzzle in the apparent effect of a magnetic field on the critical temperature of the QCD chiral transition; and they led us to establish by the first time that the core of the observed two-solar-mass neutron stars could be made up of quark matter in certain inhomogeneous chiral phases in a magnetic field and that this was consistent with current astrophysical observations. A major goal established by the Nuclear Science Advisory committee in its most recent report “Reaching for the Horizon” has been “to truly understand how nuclei and strongly interacting matter in all its forms behave and can predict their behavior in new settings.” The results found in this DOE project have all contributed to address this goal, and thus they are important for advancing fundamental knowledge in the area of nuclear physics and for enhancing our understanding of the role of strong magnetic fields in the two settings where they are most relevant, neutron stars and heavy-ion collisions.

  12. Uncovering the single top: observation of electroweak top quark production

    SciTech Connect (OSTI)

    Benitez, Jorge Armando; /Michigan State U.

    2009-08-01

    The top quark is generally produced in quark and anti-quark pairs. However, the Standard Model also predicts the production of only one top quark which is mediated by the electroweak interaction, known as 'Single Top'. Single Top quark production is important because it provides a unique and direct way to measure the CKM matrix element V{sub tb}, and can be used to explore physics possibilities beyond the Standard Model predictions. This dissertation presents the results of the observation of Single Top using 2.3 fb{sup -1} of Data collected with the D0 detector at the Fermilab Tevatron collider. The analysis includes the Single Top muon+jets and electron+jets final states and employs Boosted Decision Tress as a method to separate the signal from the background. The resulting Single Top cross section measurement is: (1) {sigma}(p{bar p} {yields} tb + X, tqb + X) = 3.74{sub -0.74}{sup +0.95} pb, where the errors include both statistical and systematic uncertainties. The probability to measure a cross section at this value or higher in the absence of signal is p = 1.9 x 10{sup -6}. This corresponds to a standard deviation Gaussian equivalence of 4.6. When combining this result with two other analysis methods, the resulting cross section measurement is: (2) {sigma}(p{bar p} {yields} tb + X, tqb + X) = 3.94 {+-} 0.88 pb, and the corresponding measurement significance is 5.0 standard deviations.

  13. Ger te und Akkumulatorwerk Zwickau GmbH GAZ | Open Energy Information

    Open Energy Info (EERE)

    Zwickau GmbH (GAZ) Place: Germany Product: GAZ manufactures special nickel-based batteries mainly used in the energy, rail, telecom and UPS sectors. References: Gerte- und...

  14. GEWI Planungs und Vertriebsgesellschaft mbH Co KG | Open Energy...

    Open Energy Info (EERE)

    Vertriebsgesellschaft mbH & Co KG Place: Husum Nordsee, Germany Zip: 25813 Sector: Wind energy Product: Wind energy project developer. References: GEWI Planungs- und...

  15. Thermal axion production in the primordial quark-gluon plasma

    SciTech Connect (OSTI)

    Graf, Peter; Steffen, Frank Daniel

    2011-04-01

    We calculate the rate for thermal production of axions via scattering of quarks and gluons in the primordial quark-gluon plasma. To obtain a finite result in a gauge-invariant way that is consistent to leading order in the strong gauge coupling, we use systematic field theoretical methods such as hard thermal loop resummation and the Braaten-Yuan prescription. The thermally produced yield, the decoupling temperature, and the density parameter are computed for axions with a mass below 10 meV. In this regime, with a Peccei-Quinn scale above 6x10{sup 8} GeV, the associated axion population can still be relativistic today and can coexist with the axion cold dark matter condensate.

  16. Quantum simulations of strongly coupled quark-gluon plasma

    SciTech Connect (OSTI)

    Filinov, V. S.; Ivanov, Yu. B.; Bonitz, M.; Levashov, P. R.; Fortov, V. E.

    2011-09-15

    A strongly coupled quark-gluon plasma (QGP) of heavy constituent quasiparticles is studied by a path-integral Monte-Carlo method. This approach is a quantum generalization of the model developed by B.A. Gelman, E.V. Shuryak, and I. Zahed. It is shown that this method is able to reproduce the QCD lattice equation of state and also yields valuable insight into the internal structure of the QGP. The results indicate that the QGP reveals liquid-like rather than gas-like properties. At temperatures just above the critical one it was found that bound quark-antiquark states still survive. These states are bound by effective string-like forces and turn out to be colorless. At the temperature as large as twice the critical one no bound states are observed. Quantum effects turned out to be of prime importance in these simulations.

  17. The physics of hot and dense quark-gluon matter

    SciTech Connect (OSTI)

    Kharzeev, Dmitri E

    2012-05-10

    This technical report describes the work done under the DOE grant DE-FG-88ER41723 (final award number DE-SC0005645), "The physics of hot and dense quark-gluon matter", during the year of 12/01/2010 through 11/30/2011. As planned in the proposal, the performed research focused along two main thrusts: 1) topological effects in hot quark-gluon matter and 2) phenomenology of relativistic heavy ion collisions. The results of research are presented in 12 papers published in reputable refereed journals (Physical Review Letters, Physical Review, Physics Letters and Nuclear Physics). All of the performed research is directly related to the experimental programs of DOE, especially at the Relativistic Heavy Ion Collider. Much of it also has broader interdisciplinary implications - for example, the work on the non-dissipative chiral magnetic current is directly relevant for quantum computing. The attached report describes the performed work in detail.

  18. Angular correlations in top quark decays in standard model extensions

    SciTech Connect (OSTI)

    Batebi, S.; Etesami, S. M.; Mohammadi-Najafabadi, M.

    2011-03-01

    The CMS Collaboration at the CERN LHC has searched for the t-channel single top quark production using the spin correlation of the t-channel. The signal extraction and cross section measurement rely on the angular distribution of the charged lepton in the top quark decays, the angle between the charged lepton momentum and top spin in the top rest frame. The behavior of the angular distribution is a distinct slope for the t-channel single top (signal) while it is flat for the backgrounds. In this Brief Report, we investigate the contributions which this spin correlation may receive from a two-Higgs doublet model, a top-color assisted technicolor (TC2) and the noncommutative extension of the standard model.

  19. Forward-backward asymmetry in top quark-antiquark production

    SciTech Connect (OSTI)

    Abazov, V.M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G. A.; Aoki, M.; Arov, M.; Askew, A.; Asman, B.; Atramentov, O.; Avila, C.; BackusMayes, J.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Beale, S.; Bean, A.; Begalli, M.; Begel, M.; Belanger-Champagne, C.; Bellantoni, L.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besancon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; Boos, E. E.; Borissov, G.; Bose, T.; Brandt, A.; Brandt, O.; Brock, R.; Brooijmans, G.; Bross, A.; Brown, D.; Brown, J.; Bu, X. B.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Burnett, T. H.; Buszello, C. P.; Calpas, B.; Camacho-Perez, E.; Carrasco-Lizarraga, M. A.; Casey, B. C. K.; Castilla-Valdez, H.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chen, G.; Chevalier-Thery, S.; Cho, D. K.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M. -C.; Croc, A.; Cutts, D.; Das, A.; Davies, G.; De, K.; de Jong, S. J.; De La Cruz-Burelo, E.; Deliot, F.; Demarteau, M.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Ding, P. F.; Dominguez, A.; Dorland, T.; Dubey, A.; Dudko, L. V.; Duggan, D.; Duperrin, A.; Dutt, S.; Dyshkant, A.; Eads, M.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Enari, Y.; Evans, H.; Evdokimov, A.; Evdokimov, V. N.; Facini, G.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Garcia-Bellido, A.; Gavrilov, V.; Gay, P.; Geng, W.; Gerbaudo, D.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Golovanov, G.; Goussiou, A.; Grannis, P. D.; Greder, S.; Greenlee, H.; Greenwood, Z. D.; Gregores, E. M.; Grenier, G.; Gris, Ph; Grivaz, J. -F.; Grohsjean, A.; Gruenendahl, S.; Gruenewald, M. W.; Guillemin, T.; Guo, F.; Gutierrez, G.; Gutierrez, P.; Haas, A.; Hagopian, S.; Haley, J.; Han, L.; Harder, K.; Harel, A.; Hauptman, J. M.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hoeneisen, B.; Hohlfeld, M.; Hubacek, Z.; Huske, N.; Hynek, V.; Iashvili, I.; Ilchenko, Y.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffre, M.; Jamin, D.; Jayasinghe, A.; Jesik, R.; Johns, K.; Johnson, M.; Johnston, D.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; Juste, A.; Kaadze, K.; Kajfasz, E.; Karmanov, D.; Kasper, P. A.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Kirby, M. H.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kulikov, S.; Kumar, A.; Kupco, A.; Kurca, T.; Kuzmin, V. A.; Kvita, J.; Lammers, S.; Landsberg, G.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lellouch, J.; Li, L.; Li, Q. Z.; Lietti, S. M.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, Y.; Liu, Z.; Lobodenko, A.; Lokajicek, M.; de Sa, R. Lopes; Lubatti, H. J.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Mackin, D.; Madar, R.; Magana-Villalba, R.; Malik, S.; Malyshev, V. L.; Maravin, Y.; Martinez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Meyer, A.; Meyer, J.; Miconi, F.; Mondal, N. K.; Muanza, G. S.; Mulhearn, M.; Nagy, E.; Naimuddin, M.; Narain, M.; Nayyar, R.; Neal, H. A.; Negret, J. P.; Neustroev, P.; Novaes, S. F.; Nunnemann, T.; Obrant, G.; Orbaker, D.; Orduna, J.; Osman, N.; Osta, J.; et. al.

    2011-12-12

    We present a measurement of forward-backward asymmetry in top quark-antiquark production in proton-antiproton collisions in the final state containing a lepton and at least four jets. Using a data set corresponding to an integrated luminosity of 5.4 fb{sup -1}, collected by the D0 experiment at the Fermilab Tevatron Collider, we measure the t{bar t} forward-backward asymmetry to be (9.2 {+-} 3.7)% at the reconstruction level. When corrected for detector acceptance and resolution, the asymmetry is found to be (19.6 {+-} 6.5)%. We also measure a corrected asymmetry based on the lepton from a top quark decay, found to be (15.2 {+-} 4.0)%. The results are compared to predictions based on the next-to-leading-order QCD generator mc@nlo. The sensitivity of the measured and predicted asymmetries to the modeling of gluon radiation is discussed.

  20. NLO evolution of 3-quark Wilson loop operator

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Balitsky, I.; Grabovsky, A. V.

    2015-01-07

    It is well known that high-energy scattering of a meson from some hadronic target can be described by the interaction of that target with a color dipole formed by two Wilson lines corresponding to fast quark-antiquark pair. Moreover, the energy dependence of the scattering amplitude is governed by the evolution equation of this color dipole with respect to rapidity. Similarly, the energy dependence of scattering of a baryon can be described in terms of evolution of a three-Wilson-lines operator with respect to the rapidity of the Wilson lines. We calculate the evolution of the 3-quark Wilson loop operator in themore » next-to-leading order (NLO) and present a quasi-conformal evolution equation for a composite 3-Wilson-lines operator. Thus we also obtain the linearized version of that evolution equation describing the amplitude of the odderon exchange at high energies.« less

  1. Forward-backward asymmetry in top quark-antiquark production

    SciTech Connect (OSTI)

    Abazov, Victor Mukhamedovich [Dubna, JINR; Abbott, Braden Keim [Oklahoma U.; Acharya, Bannanje Sripath [Tata Inst.; Adams, Mark Raymond [Illinois U., Chicago; Adams, Todd [Florida State U.; Alexeev, Guennadi D [Dubna, JINR; Alkhazov, Georgiy D [St. Petersburg, INP; Alton, Andrew K [Michigan U.; Augustana Coll., Sioux Falls; Alverson, George O [Northeastern U.; Alves, Gilvan Augusto [Rio de Janeiro, CBPF; Aoki, Masato [Fermilab; Louisiana Tech. U.

    2011-12-12

    We present a measurement of forward-backward asymmetry in top quark-antiquark production in proton-antiproton collisions in the final state containing a lepton and at least four jets. Using a dataset corresponding to an integrated luminosity of 5.4 fb-1, collected by the D0 experiment at the Fermilab Tevatron Collider, we measure the t{bar t} forward-backward asymmetry to be (9.2 3.7)% at the reconstruction level. When corrected for detector acceptance and resolution, the asymmetry is found to be (19.6 6.5)%. We also measure a corrected asymmetry based on the lepton from a top quark decay, found to be (15.2 4.0)%. The results are compared to predictions based on the next-to-leading-order QCD generator mc@nlo. The sensitivity of the measured and predicted asymmetries to the modeling of gluon radiation is discussed.

  2. Why should we care about the top quark Yukawa coupling?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Shapshnikov, Mikhail; Bezrukov, Fedor

    2015-04-15

    In the cosmological context, for the Standard Model to be valid up to the scale of inflation, the top quark Yukawa coupling yt should not exceed the critical value ytcrit , coinciding with good precision (about 0.2‰) with the requirement of the stability of the electroweak vacuum. So, the exact measurements of yt may give an insight on the possible existence and the energy scale of new physics above 100 GeV, which is extremely sensitive to yt. In this study, we overview the most recent theoretical computations of and the experimental measurements of ytcrit and the experimental measurements ofmore » yt. Within the theoretical and experimental uncertainties in yt, the required scale of new physics varies from 10⁷ GeV to the Planck scale, urging for precise determination of the top quark Yukawa coupling.« less

  3. Two-component quark-gluon plasma in stringy models

    SciTech Connect (OSTI)

    Verschelde, H.; Zakharov, V. I.

    2011-05-23

    The two-component liquid model reproduces the basic properties of the quark-gluon plasma as observed in heavy-ion collisions. The key dynamic element of the model is existence of a light scalar. We argue that existence of such a scalar is a generic feature of the stringy models of quantum chromodynamics. The lattice data provides evidence for a condensed, three-dimensional scalar field as well. We outline a possible crucial check of the model on the lattice.

  4. Classical strongly coupled quark-gluon plasma. V. Structure factors

    SciTech Connect (OSTI)

    Cho, Sungtae; Zahed, Ismail

    2010-10-15

    We show that the classical and strongly coupled quark-gluon plasma is characterized by a multiple of structure factors that obey generalized Orstein-Zernicke equations. We use the canonical partition function and its associated density functional to derive analytical equations for the density and charge monopole structure factors for arbitrary values of {Gamma}=V/K, the ratio of the mean potential to the Coulomb energy. The results are compared with SU(2) molecular dynamics simulations.

  5. Quantum simulations of strongly coupled quark-gluon plasma

    SciTech Connect (OSTI)

    Filinov, V. S.; Ivanov, Yu. B.; Bonitz, M.; Levashov, P. R.; Fortov, V. E.

    2012-06-15

    A strongly coupled quark-gluon plasma (QGP) of heavy constituent quasi-particles is studied by a path-integral Monte-Carlo method. This approach is a quantum generalization of the classical molecular dynamics by Gelman, Shuryak, and Zahed. It is shown that this method is able to reproduce the QCD lattice equation of state. The results indicate that the QGP reveals liquid-like rather than gaslike properties. Quantum effects turned out to be of prime importance in these simulations.

  6. CP violating anomalous top-quark couplings at the LHC

    SciTech Connect (OSTI)

    Gupta, Sudhir Kumar; Mete, Alaettin Serhan; Valencia, G.

    2009-08-01

    We study the T odd correlations induced by CP violating anomalous top-quark couplings at both production and decay level in the process gg{yields}tt{yields}(b{mu}{sup +}{nu}{sub {mu}})(b{mu}{sup -}{nu}{sub {mu}}). We consider several counting asymmetries at the parton level and find the ones with the most sensitivity to each of these anomalous couplings at the LHC.

  7. Partial Quark-Lepton Universality and Neutrino CP Violation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liao, Jiajun; Marfatia, D.; Whisnant, K.

    2015-01-01

    We smore » tudy a model with partial quark-lepton universality that can naturally arise in grand unified theories. We find that constraints on the model can be reduced to a single condition on the Dirac CP phase δ in the neutrino sector. Using our current knowledge of the CKM and PMNS mixing matrices, we predict - 32 . 4 ° ≤ δ ≤ 32 . 0 ° at 2 σ .« less

  8. The B*Bπ coupling using relativistic heavy quarks

    SciTech Connect (OSTI)

    Flynn, J. M.; Fritzsch, P.; Kawanai, T.; Lehner, C.; Samways, B.; Sachrajda, C. T.; Van de Water, R. S.; Witzel, O.

    2015-06-23

    We report on a calculation of the B*Bπ coupling in lattice QCD. The strong matrix element (Bπ|B*) is directly related to the leading order low-energy constant in heavy meson chiral perturbation theory (HMΧPT) for B mesons. We carry out our calculation directly at the b-quark mass using a non-perturbatively tuned clover action that controls discretization effects of order |pa| and (ma)n for all n. Our analysis is performed on RBC/UKQCD gauge configurations using domain-wall fermions and the Iwasaki gauge action at two lattice spacings of a–1 = 1.729(25) GeV, a–1 = 2.281 (28) GeV, and unitary pion masses down to 290 MeV. We achieve good statistical precision and control all systematic uncertainties, giving a final result for the HMΧPT coupling gb = 0.56(3)stat(7)sys in the continuum and at the physical light-quark masses. Furthermore, this is the first calculation performed directly at the physical b-quark mass and lies in the region one would expect from carrying out an interpolation between previous results at the charm mass and at the static point.

  9. Top quark physics at the Tevatron results and prospects

    SciTech Connect (OSTI)

    K. Sliwa

    2002-10-16

    The methodology of CDF and D0 top quark analyses and their underlying assumptions are summarized. The CDF and D0 top mass averages, obtained from measurements in several channels and based on about 100 pb{sup -1} of data from p{bar p} collisions at {radical}s = 1.8 TeV collected by each experiment in Run-I, are: M{sub t} = 176.1 {+-} 4.0(stat) {+-} 5.1(syst) GeV/c{sup 2} and M{sub t} = 172.1 {+-} 5.2(stat) {+-} 4.9(syst) Gev/C{sup 2}, respectively. The combined Tevatron measurement of the top quark mass is M{sub t} = 174.3 {+-} 3.2(stat) {+-} 4.0(syst) GeV/c{sup 2}. The CDF measurement of the t{bar t} cross section (assuming M{sub t} = 175 GeV/c{sup 2}) is {sigma}{sub tt} = 6.5 {+-} {sub 1.4}{sup 1.6} pb, and the D0 value (assuming M{sub t} = 172.1 GeV/c{sup 2}) is {sigma}{sub tt} = 5.9 {+-} 1.7 pb. In anticipation of much larger statistics, prospects for top physics in Tevatron Run-II are summarized. The fact that top quark analyses are among the best windows to physics beyond the Standard Model is emphasized.

  10. Numerical simulation of the hydrodynamical combustion to strange quark matter

    SciTech Connect (OSTI)

    Niebergal, Brian; Ouyed, Rachid; Jaikumar, Prashanth

    2010-12-15

    We present results from a numerical solution to the burning of neutron matter inside a cold neutron star into stable u,d,s quark matter. Our method solves hydrodynamical flow equations in one dimension with neutrino emission from weak equilibrating reactions, and strange quark diffusion across the burning front. We also include entropy change from heat released in forming the stable quark phase. Our numerical results suggest burning front laminar speeds of 0.002-0.04 times the speed of light, much faster than previous estimates derived using only a reactive-diffusive description. Analytic solutions to hydrodynamical jump conditions with a temperature-dependent equation of state agree very well with our numerical findings for fluid velocities. The most important effect of neutrino cooling is that the conversion front stalls at lower density (below {approx_equal}2 times saturation density). In a two-dimensional setting, such rapid speeds and neutrino cooling may allow for a flame wrinkle instability to develop, possibly leading to detonation.

  11. Viscosity and dilepton production of a chemically equilibrating quark-gluon plasma at finite baryon density

    SciTech Connect (OSTI)

    Guan Nana; Li Jianwei; He Zejun; Long Jiali; Cai Xiangzhou; Ma Yugang; Shen Wenqing

    2009-07-15

    By considering the effect of shear viscosity we have investigated the evolution of a chemically equilibrating quark-gluon plasma at finite baryon density. Based on the evolution of the system we have performed a complete calculation for the dilepton production from the following processes: qq{yields}ll, qq{yields}gll, Compton-like scattering (qg{yields}qll,qg{yields}qll), gluon fusion (gg{yields}cc), annihilation (qq{yields}cc), as well as the multiple scattering of quarks. We have found that quark-antiquark annihilation, Compton-like scatterring, gluon fusion, and multiple scattering of quarks give important contributions. Moreover, we have also found that the dilepton yield is an increasing function of the initial quark chemical potential, and the increase of the quark phase lifetime because of the viscosity also obviously raises the dilepton yield.

  12. Nonfactorization of four-quark condensates at low energies within chiral perturbation theory

    SciTech Connect (OSTI)

    Gomez Nicola, A.; Pelaez, J. R.; Ruiz de Elvira, J.

    2010-10-01

    Four-quark correlators and the factorization hypothesis are analyzed in the meson sector within chiral perturbation theory. We define the four-quark condensate as lim{sub x{yields}0}, which is equivalent to other definitions commonly used in the literature. Factorization of the four-quark condensate holds to leading and next to leading order. However, at next to next to leading order, a term with a nontrivial space-time dependence in the four-quark correlator yields a divergent four-quark condensate, whereas the two-quark condensate and the scalar susceptibility are finite. Such a nonfactorization term vanishes only in the chiral limit. We also comment on how factorization still holds in the large N{sub c} limit, provided such a limit is taken before renormalization.

  13. Structure functions and pair correlations of the quark-gluon plasma

    SciTech Connect (OSTI)

    Thoma, Markus H.

    2005-11-01

    Recent experiments at RHIC and theoretical considerations indicate that the quark-gluon plasma, present in the fireball of relativistic heavy-ion collisions, might be in a liquid phase. The liquid state can be identified by characteristic correlation and structure functions. Here definitions of the structure functions and pair correlations of the quark-gluon plasma are presented as well as perturbative results. These definitions might be useful for verifying the quark-gluon-plasma liquid in QCD lattice calculations.

  14. Heavy Quarks, QCD, and Effective Field Theory (Technical Report) | SciTech

    Office of Scientific and Technical Information (OSTI)

    Connect Technical Report: Heavy Quarks, QCD, and Effective Field Theory Citation Details In-Document Search Title: Heavy Quarks, QCD, and Effective Field Theory The research supported by this OJI award is in the area of heavy quark and quarkonium production, especially the application Soft-Collinear E#11;ective Theory (SCET) to the hadronic production of quarkonia. SCET is an e#11;ffective theory which allows one to derive factorization theorems and perform all order resummations for QCD

  15. Doubly heavy baryons and quark-diquark symmetry in quenched and partially

    Office of Scientific and Technical Information (OSTI)

    quenched chiral perturbation theory (Journal Article) | SciTech Connect Doubly heavy baryons and quark-diquark symmetry in quenched and partially quenched chiral perturbation theory Citation Details In-Document Search Title: Doubly heavy baryons and quark-diquark symmetry in quenched and partially quenched chiral perturbation theory We extend the chiral Lagrangian with heavy quark-diquark symmetry to quenched and partially quenched theories. These theories are used to derive formulae for the

  16. Two-color quark matter: U(1){sub A} restoration, superfluidity, and

    Office of Scientific and Technical Information (OSTI)

    quarkyonic phase (Journal Article) | SciTech Connect Two-color quark matter: U(1){sub A} restoration, superfluidity, and quarkyonic phase Citation Details In-Document Search Title: Two-color quark matter: U(1){sub A} restoration, superfluidity, and quarkyonic phase We discuss the phase structure of quantum chromodynamics (QCD) with two colors and two flavors of light quarks. This is motivated by the increasing interest in the QCD phase diagram as follows: (1) The QCD critical point search

  17. Exotic Physics with the Top Quark at the LHC. End of grant report

    SciTech Connect (OSTI)

    Black, Kevin

    2013-07-29

    The grant supported two main activities : searching for new physics with the top quark at the LHC and development of the ATLAS muon trigger.

  18. Improving the Top Quark Forward-Backward Asymmetry Measurement at the LHC

    SciTech Connect (OSTI)

    Bai, Yang; Han, Zhenyu; /Harvard U., Phys. Dept.

    2011-08-15

    At the LHC, top quark pairs are dominantly produced from gluons, making it difficult to measure the top quark forward-backward asymmetry. To improve the asymmetry measurement, we study variables that can distinguish between top quarks produced from quarks and those from gluons: the invariant mass of the top pair, the rapidity of the top-antitop system in the lab frame, the rapidity of the top quark in the top-antitop rest frame, the top quark polarization and the top-antitop spin correlation. We combine all the variables in a likelihood discriminant method to separate quark-initiated events from gluon-initiated events. We apply our method on models including G-prime's and W-prime's motivated by the recent observation of a large top quark forward-backward asymmetry at the Tevatron. We have found that the significance of the asymmetry measurement can be improved by 10% to 30%. At the same time, the central values of the asymmetry increase by 40% to 100%. We have also analytically derived the best spin quantization axes for studying top quark polarization as well as spin-correlation for the new physics models.

  19. Doubly heavy baryons and quark-diquark symmetry in quenched and...

    Office of Scientific and Technical Information (OSTI)

    A quark-diquark symmetry prediction for the hyperfine splittings of heavy mesons and doubly heavy baryons is rather insensitive to chiral corrections in both quenched and partially ...

  20. Electroweak production of top-quark pairs in e + e - annihilation...

    Office of Scientific and Technical Information (OSTI)

    Electroweak production of top-quark pairs in e + e - annihilation at NNLO in QCD: The vector current contributions Citation Details In-Document Search Title: Electroweak production ...

  1. Comparison of jet quenching formalisms for a quark-gluon plasma...

    Office of Scientific and Technical Information (OSTI)

    Title: Comparison of jet quenching formalisms for a quark-gluon plasma "brick" Authors: Armesto, Nestor ; Cole, Brian ; Gale, Charles ; Horowitz, William A. ; Jacobs, Peter ; Jeon, ...

  2. Top quark properties from the Tevatron (Conference) | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Top quark properties from the Tevatron Citation Details In-Document Search Title: Top quark properties from the Tevatron This report describes latest measurements and studies of top quark properties from the Tevatron in Run II with an integrated luminosity of up to 750 pb{sup -1}. Due to its large mass of about 172 GeV/c{sup 2}, the top quark provides a unique environment for tests of the Standard Model and is believed to yield sensitivity to new physics beyond the Standard Model. With data

  3. Search for vector-like T quarks decaying to top quarks and Higgs bosons in the all-hadronic channel using jet substructure

    SciTech Connect (OSTI)

    Khachatryan, V.

    2015-06-12

    A search is performed for a vector-like heavy T quark that is produced in pairs and that decays to a top quark and a Higgs boson. The data analysed correspond to an integrated luminosity of 19.7 fb? collected with the CMS detector in proton-proton collisions at ?s = 8 TeV. For T quarks with large mass values the top quarks and Higgs bosons can have significant Lorentz boosts, so that their individual decay products often overlap and merge. Methods are applied to resolve the substructure of such merged jets. Upper limits on the production cross section of a T quark with mass between 500 and 1000 GeV/c are derived. If the T quark decays exclusively to tH, the observed (expected) lower limit on the mass of the T quark is 745 (773) GeV/c at 95% confidence level. For the first time an algorithm is used for tagging boosted Higgs bosons that is based on a combination of jet substructure information and b tagging.

  4. Search for vector-like T quarks decaying to top quarks and Higgs bosons in the all-hadronic channel using jet substructure

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-06-12

    We performed a search for a vector-like heavy T quark that is produced in pairs and that decays to a top quark and a Higgs boson. The data analysed correspond to an integrated luminosity of 19.7 fb-1collected with the CMS detector in proton-proton collisions at √s=8 TeV. For T quarks with large mass values the top quarks and Higgs bosons can have significant Lorentz boosts, so that their individual decay products often overlap and merge. Methods are applied to resolve the substructure of such merged jets. We also derived upper limits on the production cross section of a T quark with mass between 500 and 1000 GeV/c 2. If the T quark decays exclusively to tH, the observed (expected) lower limit on the mass of the T quark is 745 (773) GeV/c 2 at 95% confidence level. For the first time an algorithm is used for tagging boosted Higgs bosons that is based on a combination of jet substructure information and b tagging.

  5. Yoctosecond Photon Pulses from Quark-Gluon Plasmas

    SciTech Connect (OSTI)

    Ipp, Andreas; Keitel, Christoph H.; Evers, Joerg

    2009-10-09

    Present ultrafast laser optics is at the frontier between atto- and zeptosecond photon pulses, giving rise to unprecedented applications. We show that high-energetic photon pulses down to the yoctosecond time scale can be produced in heavy-ion collisions. We focus on photons produced during the initial phase of the expanding quark-gluon plasma. We study how the time evolution and properties of the plasma may influence the duration and shape of the photon pulse. Prospects for achieving double-peak structures suitable for pump-probe experiments at the yoctosecond time scale are discussed.

  6. Viscous quark-gluon plasma model through fluid QCD approach

    SciTech Connect (OSTI)

    Djun, T. P.; Soegijono, B.; Mart, T.; Handoko, L. T. E-mail: Laksana.tri.handoko@lipi.go.id

    2014-09-25

    A Lagrangian density for viscous quark-gluon plasma has been constructed within the fluid-like QCD framework. Gauge symmetry is preserved for all terms inside the Lagrangian, except for the viscous term. The transition mechanism from point particle field to fluid field, and vice versa, are discussed. The energy momentum tensor that is relevant to the gluonic plasma having the nature of fluid bulk of gluon sea is derived within the model. By imposing conservation law in the energy momentum tensor, shear viscosity appears as extractable from the equation.

  7. Radiative energy loss in an anisotropic quark-gluon plasma

    SciTech Connect (OSTI)

    Roy, Pradip; Dutt-Mazumder, Abhee K.

    2011-04-15

    We calculate radiative energy loss of heavy and light quarks in an anisotropic medium (static) in a first-order opacity expansion. Such an anisotropy can result from the initial rapid longitudinal expansion of the matter created in relativistic heavy-ion collisions. Significant dependency of the energy loss on the anisotropy parameter {xi} and the direction of propagation of the partons with respect to the anisotropy axis is found. It is shown that the introduction of early-time momentum-space anisotropy can enhance the fractional energy loss in the direction of the anisotropy, whereas it decreases when the parton propagates perpendicular to the direction of the anisotropy.

  8. Spectral sum rules for the quark-gluon plasma

    SciTech Connect (OSTI)

    Romatschke, P.; Son, D. T.

    2009-09-15

    We derive sum rules involving the spectral density of the stress-energy tensor in N=4 super-Yang-Mills theory and pure Yang-Mills theory. The sum rules come from the hydrodynamic behavior at small momenta and the conformal (in the case of N=4 super-Yang-Mills theory) or asymptotically free (as for the pure Yang-Mills theory) behavior at large momenta. These sum rules may help constrain quark-gluon plasma transport coefficients obtained from lattice QCD.

  9. Quasilinear transport approach to equilibration of quark-gluon plasmas

    SciTech Connect (OSTI)

    Mrowczynski, Stanislaw; Mueller, Berndt

    2010-03-15

    We derive the transport equations of quark-gluon plasma in the quasilinear approximation. The equations are either of the Balescu-Lenard or Fokker-Planck form. The plasma's dynamics is assumed to be governed by longitudinal chromoelectric fields. The isotropic plasma, which is stable, and the two-stream system, which is unstable, are considered in detail. A process of equilibration is briefly discussed in both cases. The peaks of the two-stream distribution are shown to rapidly dissolve in time.

  10. Direct photon production from viscous quark-gluon plasma

    SciTech Connect (OSTI)

    Chaudhuri, A. K.; Sinha, Bikash

    2011-03-15

    We simulate direct photon production in the evolution of viscous quark-gluon plasma medium. Photons from Compton and annihilation processes are considered. The viscous effect on photon production is very strong and reliable simulation is possible only in a limited p{sub T} range. For minimally viscous fluid ({eta}/s=0.08), direct photons can be reliably computed only up to p{sub T}{<=}1.3 GeV. With reduced viscosity ({eta}/s=0.04), the limit increases to p{sub T}{<=}2 GeV.

  11. The heavy Top Quark Partner in Little Higgs Models

    SciTech Connect (OSTI)

    Larios, F.; Perez, M. A.; Penunuri, F.

    2008-07-02

    Little Higgs models provide a natural explanation for the lightness of the Higgs mass. Through the mechanism of collective symmetry breaking, one loop quadratic divergent contributions to the Higgs mass are avoided. In these models a heavy partner of the Top quark appears as required to cancel out the Top's loop contribution. This heavy Top could be produced at the LHC mainly in the single mode. Because of flavor mixing a large FCNC gtT coupling can be generated at one loop that could boost the single T production mode through gg fusion.

  12. Unified spin gauge model and the top quark mass

    SciTech Connect (OSTI)

    Chisholm, J.S.R.; Farwell, R.S.

    1995-10-01

    Spin gauge models use a real Clifford algebraic structure R{sub p,q} associated with a real manifold of dimension p + q to describe the fundamental interactions of elementary particles. This review provides a comparison between those models and the standard model, indicating their similarities and differences. By contrast with the standard model, the spin gauge model based on R{sub 3,8} generates intermediate boson mass terms without the need to use the Higgs-Kibble mechanism and produces a precise prediction for the mass of the top quark. The potential of this model to account for exactly three families of fermions is considered.

  13. B1487(01)Quarks FM.i-xvi

    National Nuclear Security Administration (NNSA)

    Committee on the Physics of the Universe Board on Physics and Astronomy Division on Engineering and Physical Sciences THE NATIONAL ACADEMIES PRESS Washington, D.C. www.nap.edu Quarks Eleven Science Questions for the New Century with the Cosmos Connecting THE NATIONAL ACADEMIES PRESS 500 Fifth Street, N.W. Washington, DC 20001 NOTICE: The project that is the subject of this report was approved by the Govern- ing Board of the National Research Council, whose members are drawn from the councils of

  14. Probing Quark-Gluon Interactions with Transverse Polarized Scattering

    SciTech Connect (OSTI)

    Slifer, K.; Rondon, O. A.; Crabb, D.; Day, D.; Frlez, E.; Lindgren, R.; McKee, P.; Norum, B.; Pocanic, D.; Prok, Y.; Sawatzky, B.; Smith, C.; Tajima, S.; Wang, K.; Zeier, M.; Zhu, H.; Aghalaryan, A.; Asaturyan, R.; Mkrtchyan, H.; Ahmidouch, A.

    2010-09-03

    We have extracted QCD matrix elements from our data on doubly polarized inelastic scattering of electrons on nuclei. We find the higher twist matrix element d{sub 2}-tilde, which arises strictly from quark-gluon interactions, to be unambiguously nonzero. The data also reveal an isospin dependence of higher twist effects if we assume that the Burkhardt-Cottingham sum rule is valid. The fundamental Bjorken sum rule obtained from the a{sub 0} matrix element is satisfied at our low momentum transfer.

  15. Characteristics of multimuon events from fourth generation quarks at the SSC (superconducting super collider)

    SciTech Connect (OSTI)

    Baer, H.

    1987-08-14

    Multimuon events can be a distinctive signature for pair production of t-quarks or 4th generation quarks at the SSC. In this paper we address aspects of the multimuon event topology relevant to detector design for the SSC. In particular, we discuss energy measurement, rapidity range, segmentation and the need for hadronic calorimetry in a dedicated muon detector.

  16. Status of the top quark: Top production cross section and top properties

    SciTech Connect (OSTI)

    Boisvert, V.; /Rochester U.

    2006-08-01

    This report describes the latest cross section and property measurements associated with the top quark at the Tevatron Run II. The largest data sample used is 760 pb{sup -1} of integrated luminosity. Due to its large mass, the top quark might be involved in the process of electroweak symmetry breaking, making it a useful probe for signs of new physics.

  17. Aspects of the strongly interacting matter phase diagram within non-local quark models

    SciTech Connect (OSTI)

    Pagura, V.; Dumm, D. G.; Scoccola, N. N.

    2013-03-25

    We study a nonlocal extension of the so-called Polyakov Nambu-Jona-Lasinio model at finite temperature and chemical potential, considering the impact of the presence of dynamical quarks on the scale parameter appearing in the Polyakov potential. Both real and imaginary chemical potentials are considered. The effect of varying the current quark mass is also investigated.

  18. Production of b-quark jets at the large Hadron Collider in the parton-reggeization approach

    SciTech Connect (OSTI)

    Saleev, V. A. Shipilova, A. V.

    2013-11-15

    The inclusive hadroproduction of b-quark jets and bb-bar-quark dijets at the Large Hadron Collider is considered by using the hypothesis of gluon Reggeization in t-channel exchanges at high energies. Experimental data obtained by the ATLAS Collaboration are described well within all of the presented kinematical regions for single b-quark jets and bb-bar-quark dijets without resort to any free parameters.

  19. Adler function and hadronic contribution to the muon g-2 in a nonlocal chiral quark model

    SciTech Connect (OSTI)

    Dorokhov, Alexander E.

    2004-11-01

    The behavior of the vector Adler function at spacelike momenta is studied in the framework of a covariant chiral quark model with instantonlike quark-quark interaction. This function describes the transition between the high-energy asymptotically free region of almost massless current quarks to the low-energy hadronized regime with massive constituent quarks. The model reproduces the Adler function and V-A correlator extracted from the ALEPH and OPAL data on hadronic {tau} lepton decays, transformed into the Euclidean domain via dispersion relations. The leading order contribution from the hadronic part of the photon vacuum polarization to the anomalous magnetic moment of the muon, a{sub {mu}}{sup hvp(1)}, is estimated.

  20. Initial conditions dependency in heavy-quarks suppression in ultra-relativistic collisions

    SciTech Connect (OSTI)

    Alves Garcia Prado, Caio; Alarcon do Passo Suaide, Alexandre

    2013-05-06

    Heavy quark suppression in central Au+Au collisions is expected to be smaller than that of light quarks. However experimental data suggest that they are evenly suppressed. We propose considering fluctuations in the medium as they may lead to high-density regions which in turn can cause a considerable quark suppression at the early stages of the collision evolution. To analyse the overall effect of these fluctuations we perform computer simulations of charm and bottom propagating through the quark-gluon plasma and obtain estimates of the nuclear modification factor R{sub AA}. This quantity gives us information about the heavy quark suppression that can be compared to published experimental data from the STAR experiment.

  1. Top quark mass measurement from dilepton events at CDF II

    SciTech Connect (OSTI)

    Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G.; Ambrose, D.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; /Taiwan, Inst. Phys. /Argonne /Barcelona, IFAE /Baylor U. /INFN, Bologna /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara /Cantabria Inst. of Phys.

    2005-12-01

    We report a measurement of the top quark mass using events collected by the CDF II Detector from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron. We calculate a likelihood function for the top mass in events that are consistent with t{bar t} {yields} {bar b}{ell}{sup -}{bar {nu}}{sub {ell}}b{ell}{prime}{sup +}{nu}{sub {ell}}{prime} decays. The likelihood is formed as the convolution of the leading-order matrix element and detector resolution functions. The joint likelihood is the product of likelihoods for each of 33 events collected in 340 pb{sup -1} of integrated luminosity, yielding a top quark mass M{sub t} = 165.2 {+-} 6.1(stat.) {+-} 3.4(syst.) GeV/c{sup 2}. This first application of a matrix-element technique to t{bar t} {yields} b{ell}{sup +}{nu}{sub {ell}}{bar b}{ell}{prime}{sup -}{bar {nu}}{sub {ell}}, decays gives the most precise single measurement of M{sub t} in dilepton events. Combined with other CDF Run II measurements using dilepton events, we measure M{sub t} = 167.9 {+-} 5.2(stat.) {+-} 3.7(syst.) GeV/c{sup 2}.

  2. Forward-backward asymmetry in top quark-antiquark production

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich

    2011-12-12

    We present a measurement of forward-backward asymmetry in top quark-antiquark production in proton-antiproton collisions in the final state containing a lepton and at least four jets. Using a dataset corresponding to an integrated luminosity of 5.4 fb-1, collected by the D0 experiment at the Fermilab Tevatron Collider, we measure the t{bar t} forward-backward asymmetry to be (9.2 ± 3.7)% at the reconstruction level. When corrected for detector acceptance and resolution, the asymmetry is found to be (19.6 ± 6.5)%. We also measure a corrected asymmetry based on the lepton from a top quark decay, found to be (15.2 ± 4.0)%.more » The results are compared to predictions based on the next-to-leading-order QCD generator mc@nlo. The sensitivity of the measured and predicted asymmetries to the modeling of gluon radiation is discussed.« less

  3. Successes and failures of the constituent quark model

    SciTech Connect (OSTI)

    Lipkin, H.J.

    1982-01-01

    Our approach considers the model as a possible bridge between QCD and the experimental data and examines its predictions to see where these succeed and where they fail. We also attempt to improve the model by looking for additional simple assumptions which give better fits to the experimental data. But we avoid complicated models with too many ad hoc assumptions and too many free parameters; these can fit everything but teach us nothing. We define our constituent quark model by analogy with the constituent electron model of the atom and the constituent nucleon model of the nucleus. In the same way that an atom is assumed to consist only of constituent electrons and a central Coulomb field and a nucleus is assumed to consist only of constituent nucleons hadrons are assumed to consist only of their constituent valence quarks with no bag, no glue, no ocean, nor other constituents. Although these constituent models are oversimplified and neglect other constituents we push them as far as we can. Atomic physics has photons and vacuum polarization as well as constituent electrons, but the constituent model is adequate for calculating most features of the spectrum when finer details like the Lamb shift are neglected. 54 references.

  4. Search for vector-like T quarks decaying to top quarks and Higgs bosons in the all-hadronic channel using jet substructure

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, V.

    2015-06-12

    A search is performed for a vector-like heavy T quark that is produced in pairs and that decays to a top quark and a Higgs boson. The data analysed correspond to an integrated luminosity of 19.7 fb? collected with the CMS detector in proton-proton collisions at ?s = 8 TeV. For T quarks with large mass values the top quarks and Higgs bosons can have significant Lorentz boosts, so that their individual decay products often overlap and merge. Methods are applied to resolve the substructure of such merged jets. Upper limits on the production cross section of a T quarkmorewith mass between 500 and 1000 GeV/c are derived. If the T quark decays exclusively to tH, the observed (expected) lower limit on the mass of the T quark is 745 (773) GeV/c at 95% confidence level. For the first time an algorithm is used for tagging boosted Higgs bosons that is based on a combination of jet substructure information and b tagging.less

  5. Search for vector-like T quarks decaying to top quarks and Higgs bosons in the all-hadronic channel using jet substructure

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2015-06-12

    We performed a search for a vector-like heavy T quark that is produced in pairs and that decays to a top quark and a Higgs boson. The data analysed correspond to an integrated luminosity of 19.7 fb-1collected with the CMS detector in proton-proton collisions at √s=8 TeV. For T quarks with large mass values the top quarks and Higgs bosons can have significant Lorentz boosts, so that their individual decay products often overlap and merge. Methods are applied to resolve the substructure of such merged jets. We also derived upper limits on the production cross section of a T quarkmore » with mass between 500 and 1000 GeV/c 2. If the T quark decays exclusively to tH, the observed (expected) lower limit on the mass of the T quark is 745 (773) GeV/c 2 at 95% confidence level. For the first time an algorithm is used for tagging boosted Higgs bosons that is based on a combination of jet substructure information and b tagging.« less

  6. B-meson decay constants from 2+1-flavor lattice QCD with domain-wall light quarks and relativistic heavy quarks

    SciTech Connect (OSTI)

    Christ, Norman H.; Flynn, Jonathan M.; Izubuchi, Taku; Kawanai, Taichi; Lehner, Christoph; Soni, Amarjit; Van de Water, Ruth S.; Witzel, Oliver

    2015-03-10

    We calculate the B-meson decay constants fB, fBs, and their ratio in unquenched lattice QCD using domain-wall light quarks and relativistic b-quarks. We use gauge-field ensembles generated by the RBC and UKQCD collaborations using the domain-wall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ≈ 0.11, 0.086 fm with unitary pion masses as light as Mπ ≈ 290 MeV; this enables us to control the extrapolation to the physical light-quark masses and continuum. For the b-quarks we use the anisotropic clover action with the relativistic heavy-quark interpretation, such that discretization errors from the heavy-quark action are of the same size as from the light-quark sector. We renormalize the lattice heavy-light axial-vector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also improve the lattice heavy-light current through O(αsa). We extrapolate our results to the physical light-quark masses and continuum using SU(2) heavy-meson chiral perturbation theory, and provide a complete systematic error budget. We obtain fB0 = 196.2(15.7) MeV, fB+ = 195.4(15.8) MeV, fBs = 235.4(12.2) MeV, fBs/fB0 = 1.193(59), and fBs/fB+ = 1.220(82), where the errors are statistical and total systematic added in quadrature. In addition, these results are in good agreement with other published results and provide an important independent cross check of other three-flavor determinations of B-meson decay constants using staggered light quarks.

  7. Heavy quark diffusion in strong magnetic fields at weak coupling and implications for elliptic flow

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Fukushima, Kenji; Hattori, Koichi; Yee, Ho -Ung; Yin, Yi

    2016-04-20

    In this paper, we compute the momentum diffusion coefficients of heavy quarks, κ∥ and κ⊥, in a strong magnetic field B along the directions parallel and perpendicular to B, respectively, at the leading order in QCD coupling constant αs. We consider a regime relevant for the relativistic heavy ion collisions, αseB << T2 << eB, so that thermal excitations of light quarks are restricted to the lowest Landau level (LLL) states. In the vanishing light-quark mass limit, we find κLO⊥ ∝ α2sTeB in the leading order that arises from screened Coulomb scatterings with (1+1)-dimensional LLL quarks, while κ∥ gets nomore » contribution from the scatterings with LLL quarks due to kinematic restrictions. We show that the first nonzero leading order contributions to κLO∥ come from the two separate effects: 1) the screened Coulomb scatterings with thermal gluons, and 2) a finite light-quark mass mq. The former leads to κLO,gluon∥ ∝ α2sT3 and the latter to κLO,massive∥ ∝ αs(αseB)1/2m2q. Based on our results, we propose a new scenario for the large value of heavy-quark elliptic flow observed in RHIC and LHC. Namely, when κ⊥ >> κ∥, an anisotropy in drag forces gives rise to a sizable amount of the heavy-quark elliptic flow even if heavy quarks do not fully belong to an ellipsoidally expanding background fluid.« less

  8. The Top Quark as a Window to Beyond the Standard Model Physics

    SciTech Connect (OSTI)

    Yu, Chiu-Tien

    2013-01-01

    The top quark was the last of the Standard Model quarks to be discovered, and is of considerable interest. The closeness of the top quark mass to the electroweak scale is suggestive that the top quark could be closely related to the mechanisms for electroweak symmetry breaking. Any new physics in electroweak symmetry breaking models could then preferentially couple to the top quark, making the top quark a promising probe for new physics. In this thesis, we will explore two aspects of the top quark as a harbinger to new physics: the top forward-backward asymmetry as seen at the Tevatron and the search for stops. In this thesis, we will discuss the Asymmetric Left-Right Model (ALRM), a model that is based on the gauge group $U'(1)\\times SU(2)\\times SU'(2)$ with couplings $g_1^\\prime, g_2^\\prime,$ and $g'$ associated with the fields $B',W,W'$, respectively, and show how this model can explain the top forward-backward asymmetry. We will then explore the scalar sector of the ALRM, and provide a specific Higgs mechanism that provides the masses for the $W'$ and $Z'$ bosons. The top forward-backward asymmetry is a test of invariance of charge-conjugation. Thus, we look at the $X$-gluon model, a model that was motivated by the top forward-backward asymmetry, and show that one can look at the longitudinal polarization of the top-quark to test parity conservation. Finally, we investigate searches for stop squarks, the supersymmetric partner of the top quark, at the Large Hadron Collider (LHC) using shape-based analyses.

  9. Electroweak production of top-quark pairs in e+e- annihilation at NNLO in

    Office of Scientific and Technical Information (OSTI)

    QCD: The vector current contributions (Journal Article) | SciTech Connect Electroweak production of top-quark pairs in e+e- annihilation at NNLO in QCD: The vector current contributions Citation Details In-Document Search Title: Electroweak production of top-quark pairs in e+e- annihilation at NNLO in QCD: The vector current contributions We report on a calculation of the vector current contributions to the electroweak production of top quark pairs in e+e- annihilation at

  10. Matching the quark model to the 1/N{sub c} expansion (Journal Article) |

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Matching the quark model to the 1/N{sub c} expansion Citation Details In-Document Search Title: Matching the quark model to the 1/N{sub c} expansion We compute the coefficients of the effective mass operator of the 1/N{sub c} expansion for negative parity L = 1 excited baryons using the Isgur-Karl model in order to compare the general approach, where the coefficients are obtained by fitting to data, with a specific constituent quark model calculation. We discuss the physics

  11. Precision measurement of the top quark mass in the lepton + jets channel

    Office of Scientific and Technical Information (OSTI)

    using a matrix element method with Quasi-Monte Carlo integration (Thesis/Dissertation) | SciTech Connect Thesis/Dissertation: Precision measurement of the top quark mass in the lepton + jets channel using a matrix element method with Quasi-Monte Carlo integration Citation Details In-Document Search Title: Precision measurement of the top quark mass in the lepton + jets channel using a matrix element method with Quasi-Monte Carlo integration This thesis presents a measurement of the top quark

  12. Mixings of four-quark components in light nonsinglet scalar mesons in QCD sum rules

    SciTech Connect (OSTI)

    Sugiyama, J.; Nakamura, T.; Nishikawa, T.; Oka, M.; Ishii, N.

    2007-12-01

    Mixings of four-quark components in the nonsinglet scalar mesons are studied in the QCD sum rules. We propose a formulation to evaluate the cross correlators of qq and qqqq operators and to define the mixings of different Fock states in the sum rule. It is applied to the nonsinglet scalar mesons, a{sub 0} and K{sub 0}*. It is found that the four-quark operators predict lower masses than the qq operators and that the four-quark states occupy about 70%-90% of the lowest mass states.

  13. G-Zero Experiment Proves Strange Quark Effects Not That Big | Jefferson Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    G-Zero Experiment Proves Strange Quark Effects Not That Big G-Zero Experiment Proves Strange Quark Effects Not That Big Strange Wheel - This ferris wheel is part of a system that helped determine just how strange the ordinary stuff around us can be. In the G-Zero experiment, researchers carried out a precisely tuned survey for ephemeral particles that appear only briefly inside matter. G-Zero Experiment Proves Strange Quark Effects Not That Big It's been said that anything worth doing takes time

  14. Suppression of the shear viscosity in a 'semi'-quark-gluon plasma (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Suppression of the shear viscosity in a 'semi'-quark-gluon plasma Citation Details In-Document Search Title: Suppression of the shear viscosity in a 'semi'-quark-gluon plasma We consider QCD at temperatures T near T{sub c}, where the theory deconfines. We distinguish between a 'complete' quark-gluon plasma (QGP), where the vacuum expectation value of the renormalized Polyakov loop is near unity, essentially constant with T, and the 'semi'-QGP, where the loop

  15. Testing for three-body quark forces in L = 1 excited baryons (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Testing for three-body quark forces in L = 1 excited baryons Citation Details In-Document Search Title: Testing for three-body quark forces in L = 1 excited baryons We discuss the matching of the quark model to the effective mass operator of the 1/N{sub c} expansion using the permutation group S{sub N}. As an illustration of the general procedure we perform the matching of the Isgur-Karl model for the spectrum of the negative parity L = 1 excited baryons. Assuming

  16. Two-loop ultrasoft running of the O(v{sup 2}) QCD quark potentials (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Two-loop ultrasoft running of the O(v{sup 2}) QCD quark potentials Citation Details In-Document Search Title: Two-loop ultrasoft running of the O(v{sup 2}) QCD quark potentials The two-loop ultrasoft contributions to the next-to-leading logarithmic (NLL) running of the QCD potentials at order v{sup 2} are determined. The results represent an important step towards the next-to-next-to-leading logarithmic (NNLL) description of heavy quark pair production and

  17. Charm and strange quark masses and f D s from overlap fermions...

    Office of Scientific and Technical Information (OSTI)

    f D s from overlap fermions Citation Details In-Document Search This content will become publicly available on August 25, 2016 Title: Charm and strange quark masses and f D s from ...

  18. VariableR Reclustering in Multiple Top Quark and W Boson Events

    SciTech Connect (OSTI)

    Hyde, Jeremy

    2015-08-14

    VariableR jet reclustering is an innovative technique that allows for the reconstruction of boosted object over a wide range of kinematic regimes. Such capability enables the efficient identification of events with multiple boosted top quarks which is a typical signature for new physics processes such as the production of the supersymmetric partner of the gluon. In order to evaluate the performance of the algorithm, the VariableR reclustered jets are compared with fixed radius reclustered jets. The flexibility of the algorithm is tested by reconstructing both boosted top quarks and boosted W bosons. The VariableR reclustering method is found to be more efficient than the fixed radius algorithm at identifying top quarks and W bosons in events with four top quarks, therefore enhancing the sensitivity for gluino searches.

  19. VariableR reclustering in multiple top quark events - Oral Presentation

    SciTech Connect (OSTI)

    Hyde, Jeremy; /SLAC

    2015-08-22

    VariableR jet reclustering is an innovative technique that allows for the reconstruction of boosted object over a wide range of kinematic regimes. Such capability enables the efficient identification of events with multiple boosted top quarks which is a typical signature for new physics processes such as the production of the supersymmetric partner of the gluon. In order to evaluate the performance of the algorithm, the VariableR reclustered jets are compared with fixed radius reclustered jets. The flexibility of the algorithm is tested by reconstructing both boosted top quarks and boosted W bosons. The VariableR reclustering method is found to be more efficient than the fixed radius algorithm at identifying top quarks and W bosons in events with four top quarks, therefore enhancing the sensitivity for gluino searches.

  20. Electroweak production of top-quark pairs in e+e- annihilation...

    Office of Scientific and Technical Information (OSTI)

    Electroweak production of top-quark pairs in e+e- annihilation at NNLO in QCD: the vector contributions Citation Details In-Document Search Title: Electroweak production of...

  1. Seeing Quarks and Gluons Through Jets and Silhouettes | U.S....

    Office of Science (SC) Website

    ... Each award funds a scientist for five years. The 2.5-million grant allowed him to devise and test a new way to study the fundamental particles. While firing quarks and gluons into ...

  2. Quark-Hadron Duality in Neutron (3He) Spin Structure (Journal...

    Office of Scientific and Technical Information (OSTI)

    We present experimental results of the first high-precision test of quark-hadron duality ... SPIN; TARGETS; HELIUM 3; STRUCTURE FUNCTIONS Word Cloud More Like This Full Text ...

  3. Precise measurement of the top quark mass in the lepton+jets topology at CDF II

    SciTech Connect (OSTI)

    Abulencia, A.; Adelman, J.; Affolder, T.; Akimoto, T.; Albrow, M.G.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; Annovi, A.; Antos, J.; /Comenius U. /Tsukuba U.

    2007-03-01

    The authors present a measurement of the mass of the top quark from proton-antiproton collisions recorded at the CDF experiment in Run II of the Fermilab Tevatron. They analyze events from the single lepton plus jets final state (t{bar t} {yields} W{sup +}bW{sup -}{bar b} {yields} lvbq{bar q}{bar b}). The top quark mass is extracted using a direct calculation of the probability density that each event corresponds to the t{bar t} final state. The probability is a function of both the mass of the top quark and the energy scale of the calorimeter jets, which is constrained in situ by the hadronic W boson mass. Using 167 events observed in 955 pb{sup -1} of integrated luminosity, they achieve the single most precise measurement of the top quark mass, 170.8 {+-} 2.2(stat.) {+-} 1.4(syst.) GeV/c{sup 2}.

  4. Erratum: Two-color quark matter: U(1){sub A} restoration, superfluidit...

    Office of Scientific and Technical Information (OSTI)

    ...o-color quark matter: U(1)sub A restoration, superfluidity, and quarkyonic phase Phys. Rev. D 80, 074035 (2009) Citation Details In-Document Search Title: Erratum: Two-color ...

  5. Generalized parton distribution functions and the nucleon spin sum rules in the chiral quark soliton model

    SciTech Connect (OSTI)

    Wakamatsu, M.; Tsujimoto, H. [Department of Physics, Faculty of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

    2005-04-01

    The theoretical predictions are given for the forward limit of the unpolarized spin-flip isovector generalized parton distribution function (E{sup u}-E{sup d})(x,{xi},t) within the framework of the chiral quark soliton model, with full inclusion of the polarization of Dirac sea quarks. We observe that [(H{sup u}-H{sup d})+(E{sup u}-E{sup d})](x,0,0) has a sharp peak around x=0, which we interpret as a signal of the importance of the pionic qq excitation with large spatial extension in the transverse direction. Another interesting indication given by the predicted distribution in combination with Ji's angular momentum sum rule is that the d quark carries more angular momentum than the u quark in the proton, which may have some relation with the physics of the violation of the Gottfried sum rule.

  6. Effect of top quark spin on the Wtb couplings in e{sup +}p collisions

    SciTech Connect (OSTI)

    Atag, S.; Sahin, B.

    2006-04-01

    In our previous work [Phys. Rev. D 70, 037503 (2004)] for the e{sup +}p{yields}t{nu}+X process, we have shown that the top quark possesses a high degree of spin polarization when its spin decomposition axis is along the incoming lepton beam. In this work, the potential of ep collisions to probe an anomalous Wtb vertex is investigated via the polarized single top quark production process for TESLA+HERAp energy. The effects of the top quark polarization to Wtb couplings F{sub 2L} and F{sub 2R} are discussed. It is possible to define a polarization axis for the top quark that is more sensitive to new physics than the unpolarized case.

  7. ABSORPTION OF HARD AND THERMAL PHOTONS IN A QUARK-GLUON PLASMA...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    * 1 R. J. Fries, B. Muller, D. K. Srivastava, "High-energy photons from passage of jets through quark gluon plasma", Phys. Rev. Lett. 90, 132301 (2003). * 2 P.B. Arnold,...

  8. J/psi Production in Quark-Gluon Plasma (Journal Article) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    We solve the coupled set of transport equation for the Jpsi distribution in phase space and the hydrodynamic equation for evolution of quark-gluon plasma. At RHIC, continuous ...

  9. Study of anomalous top quark flavor-changing neutral current interactions via the tW channel of single-top-quark production

    SciTech Connect (OSTI)

    Etesami, S. M.; Mohammadi Najafabadi, M.

    2010-06-01

    The potential of the LHC for investigation of anomalous top quark interactions with gluon (tug,tcg) through the production of tW channel of single top quarks is studied. In the standard model, the single top quarks in the tW-channel mode are charge symmetric, meaning that {sigma}(pp{yields}t+W{sup -})={sigma}(pp{yields}t+W{sup +}). However, the presence of anomalous flavor-changing neutral current (FCNC) couplings leads to charge asymmetry. In this paper, a method is proposed in which this charge asymmetry may be used to constrain anomalous FCNC couplings. The strength of resulting constraints is estimated for the LHC for the center of mass energies of 7 and 14 TeV.

  10. Non-perturbative effects for the Quark-Gluon Plasma equation of state

    SciTech Connect (OSTI)

    Begun, V. V. Gorenstein, M. I. Mogilevsky, O. A.

    2012-07-15

    The non-perturbative effects for the Quark-Gluon Plasma (QGP) equation of state (EoS) are considered. The modifications of the bag model EoS are constructed to satisfy the main qualitative features observed for the QGP EoS in the lattice QCD calculations. A quantitative comparison with the lattice results is done for the SU(3) gluon plasma and for the QGP with dynamical quarks. Our analysis advocates a negative value of the bag constant B.

  11. Four top quarks in extensions of the standard model (Journal Article) |

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Four top quarks in extensions of the standard model Citation Details In-Document Search Title: Four top quarks in extensions of the standard model Authors: Grégoire, Thomas ; Katz, Emanuel ; Sanz, Veronica Publication Date: 2012-03-26 OSTI Identifier: 1098578 Type: Publisher's Accepted Manuscript Journal Name: Physical Review D Additional Journal Information: Journal Volume: 85; Journal Issue: 5; Journal ID: ISSN 1550-7998 Publisher: American Physical Society Sponsoring Org:

  12. Anisotropic flow of thermal photons as a quark-gluon plasma viscometer

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | DOE PAGES Anisotropic flow of thermal photons as a quark-gluon plasma viscometer « Prev Next » Title: Anisotropic flow of thermal photons as a quark-gluon plasma viscometer Authors: Shen, Chun ; Heinz, Ulrich ; Paquet, Jean-François ; Kozlov, Igor ; Gale, Charles Publication Date: 2015-02-19 OSTI Identifier: 1180008 Grant/Contract Number: SC0004286 Type: Publisher's Accepted Manuscript Journal Name: Physical Review C Additional Journal Information: Journal Volume: 91;

  13. One-loop matching of Delta S=2 four-quark operators with improved staggered fermions

    SciTech Connect (OSTI)

    Becher, Thomas; Gamiz, Elvira; Melnikov, Kirill; /Hawaii U.

    2005-07-01

    We compute O(alpha{sub s}) lattice-to-continuum perturbative matching coefficients for the Delta S=2 flavor changing four-quark operators for the Asqtad improved staggered action. In conjunction with lattice simulations with three flavors of light, dynamical quarks, our results yield an unquenched determination of B{sub K}, the parameter that determines the amount of indirect CP violation in the neutral kaon system. Its value is an important input for the unitarity triangle analysis of weak decays.

  14. Photon emission from a momentum-anisotropic quark-gluon plasma (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | DOE PAGES Photon emission from a momentum-anisotropic quark-gluon plasma « Prev Next » Title: Photon emission from a momentum-anisotropic quark-gluon plasma Authors: Shen, Chun ; Paquet, Jean-François ; Heinz, Ulrich ; Gale, Charles Publication Date: 2015-01-28 OSTI Identifier: 1181129 Grant/Contract Number: SC0004286; SC0004104 Type: Publisher's Accepted Manuscript Journal Name: Physical Review C Additional Journal Information: Journal Volume: 91; Journal Issue: 1; Journal ID:

  15. Pion cloud and sea quark flavor asymmetry in the impact parameter

    Office of Scientific and Technical Information (OSTI)

    representation (Conference) | SciTech Connect Pion cloud and sea quark flavor asymmetry in the impact parameter representation Citation Details In-Document Search Title: Pion cloud and sea quark flavor asymmetry in the impact parameter representation We study large-distance contributions to the nucleon parton densities in the transverse coordinate (impact parameter) representation based on generalized parton distributions (GPDs). Chiral dynamics generates a distinct component of the partonic

  16. Erratum: Two-color quark matter: U(1){sub A} restoration, superfluidity,

    Office of Scientific and Technical Information (OSTI)

    and quarkyonic phase [Phys. Rev. D 80, 074035 (2009)] (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Erratum: Two-color quark matter: U(1){sub A} restoration, superfluidity, and quarkyonic phase [Phys. Rev. D 80, 074035 (2009)] Citation Details In-Document Search Title: Erratum: Two-color quark matter: U(1){sub A} restoration, superfluidity, and quarkyonic phase [Phys. Rev. D 80, 074035 (2009)] No abstract prepared. Authors: Brauner, Tomas ; Fukushima,

  17. Comparison of jet quenching formalisms for a quark-gluon plasma "brick"

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Journal Article: Comparison of jet quenching formalisms for a quark-gluon plasma "brick" Citation Details In-Document Search Title: Comparison of jet quenching formalisms for a quark-gluon plasma "brick" Authors: Armesto, Nestor ; Cole, Brian ; Gale, Charles ; Horowitz, William A. ; Jacobs, Peter ; Jeon, Sangyong ; van Leeuwen, Marco ; Majumder, Abhijit ; Müller, Berndt ; Qin, Guang-You ; Salgado, Carlos A. ; Schenke, Björn ; Verweij,

  18. Photon emission from a momentum-anisotropic quark-gluon plasma (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Photon emission from a momentum-anisotropic quark-gluon plasma Citation Details In-Document Search Title: Photon emission from a momentum-anisotropic quark-gluon plasma Authors: Shen, Chun ; Paquet, Jean-François ; Heinz, Ulrich ; Gale, Charles Publication Date: 2015-01-28 OSTI Identifier: 1181129 Grant/Contract Number: SC0004286; SC0004104 Type: Publisher's Accepted Manuscript Journal Name: Physical Review C Additional Journal Information: Journal Volume: 91;

  19. Anisotropic flow of thermal photons as a quark-gluon plasma viscometer

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Anisotropic flow of thermal photons as a quark-gluon plasma viscometer Citation Details In-Document Search Title: Anisotropic flow of thermal photons as a quark-gluon plasma viscometer Authors: Shen, Chun ; Heinz, Ulrich ; Paquet, Jean-François ; Kozlov, Igor ; Gale, Charles Publication Date: 2015-02-19 OSTI Identifier: 1180008 Grant/Contract Number: SC0004286 Type: Publisher's Accepted Manuscript Journal Name: Physical Review C Additional Journal

  20. Search for pair production of excited top quarks in the lepton + jets final state

    SciTech Connect (OSTI)

    Chatrchyan, Serguei; et al.

    2013-11-21

    A search is performed for pair-produced spin-3/2 excited top quarks t*t * , each decaying to a top quark and a gluon. The search uses data collected with the CMS detector from pp collisions at a center-of-mass energy of ?s = 8 TeV, selecting events that have a single isolated muon or electron, an imbalance in transverse momentum, and at least six jets, of which one must be compatible with originating from the fragmentation of a b quark. The data, corresponding to an integrated luminosity of 19.5 fb-1, show no significant excess over standard model predictions, and provide a lower limit of 803 GeV at 95% confidence on the mass of the spin-3/2 t(*) quark in an extension of the Randall-Sundrum model, assuming a 100% branching fraction of its decay into a top quark and a gluon. This is the first search for a spin-3/2 excited top quark performed at the LHC.

  1. Heavy-quark production in ultrarelativistic heavy-ion collisions within a partonic transport model

    SciTech Connect (OSTI)

    Uphoff, Jan; Fochler, Oliver; Greiner, Carsten; Xu Zhe

    2010-10-15

    The production and space-time evolution of charm and bottom quarks in nucleus-nucleus collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) are investigated with the partonic transport model BAMPS (Boltzmann approach of multiparton scatterings). Heavy quarks, produced in primary hard parton scatterings during nucleon-nucleon collisions, are sampled using the Monte Carlo event generator pythia or the leading-order minijet model in conjunction with the Glauber model, revealing a strong sensitivity on the parton distribution functions, scales, and heavy-quark mass. In a comprehensive study exploring different charm masses, K factors, and possible initial gluon conditions, secondary production and the evolution of heavy quarks are examined within a fully dynamic BAMPS simulation for central heavy-ion collisions at RHIC and LHC. Although charm production in the quark-gluon plasma can be neglected at RHIC, it is significant at LHC but very sensitive to the initial conditions and the charm mass. Bottom production in the quark-gluon plasma, however, is negligible both at RHIC and LHC.

  2. A Direct Top-Quark Width Measurement from Lepton + Jets Events at CDF II

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2010-08-01

    We present a measurement of the top-quark width using t{bar t} events produced in p{bar p} collisions at Fermilab's Tevatron collider and collected by the CDF II detector. In the mode where the top quark decays to a W boson and a bottom quark, we select events in which one W decays leptonically and the other hadronically (lepton + jets channel) . From a data sample corresponding to 4.3 fb{sup -1} of integrated luminosity, we identify 756 candidate events. The top-quark mass and the mass of W boson that decays hadronically are reconstructed for each event and compared with templates of different top-quark widths ({Lambda}{sub t}) and deviations from nominal jet energy scale ({Delta}{sub JES}) to perform a simultaneous fit for both parameters, where {Delta}{sub JES} is used for the in situ calibration of the jet energy scale. By applying a Feldman-Cousins approach, we establish an upper limit at 95% confidence level (CL) of {Lambda}{sub t} < 7.6 GeV and a two-sided 68% CL interval of 0.3 GeV < {Lambda}{sub t} < 4.4 GeV for a top-quark mass of 172.5 GeV/c{sup 2}, which are consistant with the standard model prediction. This is the first direct measurement of {Lambda}{sub t} to set a lower limit with 68% CL.

  3. Search for New Physics with Top and Bottom Quarks with ATLAS

    SciTech Connect (OSTI)

    Khanov, Alexander

    2013-12-11

    The studies performed by the principal investigator during the period of the grant constitute the ground work for search for new physics in channels including top and bottom quarks with the ATLAS detector at the Large Hadron Collider. The PI has been involved in search for heavy charged Higgs bosons decaying into top and bottom quark pairs, and top quark rare decays involving Higgs bosons and c-quarks. Both channels have the top quark pair production as their main background, which was studied in detail. The search for heavy charged Higgs and top quark rare decays requires signi#12;cant amount of data accumulated by the experiment. In case no signal is observed in the present data sample collected by ATLAS (5 fb{sup -1} of integrated luminosity at proton-anti proton center-of-mass energy of 7 TeV and 20 fb{sup -1} at 8 TeV), data from the upgraded detector running at 14 TeV needs to be analyzed. The PI has been working on physics and performance studies at upgraded detector.

  4. Search for pair production of excited top quarks in the lepton + jets final state

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chatrchyan, Serguei

    2014-11-19

    A search is performed for pair-produced spin-3/2 excited top quarks t*t ¯* , each decaying to a top quark and a gluon. The search uses data collected with the CMS detector from pp collisions at a center-of-mass energy of √s = 8 TeV, selecting events that have a single isolated muon or electron, an imbalance in transverse momentum, and at least six jets, of which one must be compatible with originating from the fragmentation of a b quark. The data, corresponding to an integrated luminosity of 19.5 fb-1, show no significant excess over standard model predictions, and provide a lowermore » limit of 803 GeV at 95% confidence on the mass of the spin-3/2 t* quark in an extension of the Randall-Sundrum model, assuming a 100% branching fraction of its decay into a top quark and a gluon. As a result, this is the first search for a spin-3/2 excited top quark performed at the LHC.« less

  5. Search for Electroweak Single-Top Quark Production with the CDF II Experiment

    SciTech Connect (OSTI)

    Buehler, Matthias; /Karlsruhe U., EKP

    2006-08-01

    The CDF II experiment and the Tevatron proton-antiproton collider are parts of the Fermi National Laboratories (Fermilab). The Fermilab is located in the vicinity of Chicago, USA. Today, the Tevatron is the only collider which is able to produce the heaviest known elementary particle, the top quark. The top quark was discovered at the Tevatron by the CDF and the D0 collaborations in 1995 [1]. So far, all the top quarks found are produced via the strong interaction as top-antitop pairs. The Standard Model of elementary particle physics also predicts single-top quark production via the electroweak interaction. This production mode has not yet been observed. The CDF and the D0 collaborations have set upper limits on the cross section for that process in Run I [2, 3] and improved those results in Run II [4, 5]. Single-top quark production is one of the major interests in Run II of the Tevatron as it offers several ways to test the Standard Model and to search for potential physics beyond the Standard Model. The measurement of the cross section of singly produced top quarks via the electroweak interaction offers the possibility to determine the Cabbibo-Kobayashi-Maskawa (CKM) matrix element V{sub tb} directly. The CKM matrix defines the transformation from the eigenstates of the electroweak interactions to the mass eigenstates of the quarks. V{sub tb} gives the strength of the coupling at the Wtb vertex. The single-top quark is produced at this vertex and therefore the cross section of the single-top quark production is directly proportional to |V{sub tb}|{sup 2}. In the Standard Model, three generations of quarks and the unitarity of the CKM matrix are predicted. This leads to V{sub tb} {approx} 1. Up to now, there is no possibility to measure V{sub tb} without using the assumption that there are a certain number of quark generations. Since the measurement of the cross section of single-top quark production is independent of this assumption it could verify another prediction of the Standard Model or give hints towards physics beyond the Standard Model such as a fourth generation of quarks. In addition, electroweak single-top quark production is an important background for the Higgs boson search in the mass range of 90 GeV/c{sup 2} to 130 GeV/c{sup 2} at the Tevatron in the WH channel. Two single-top quark production modes are dominant at the Tevatron, the t-channel or W-gluon fusion and the s-channel or W* process. Since it is challenging to separate the signal from the various background events we use a neural network to combine several variables into one powerful discriminant. The simulated Monte Carlo sample outputs of the neural networks are used as templates for a likelihood fit to the outputs of the neural networks of the data. In this thesis CDF II data corresponding to an integrated luminosity of 695 pb{sup -1} is discussed. As this analysis yields no significant evidence of electroweak single-top production it is not possible to measure any cross sections. Consequently we determine upper limits on the cross sections of the t- and s-channel production separately and combined.

  6. Effects of the running of the QCD coupling on the energy loss in the quark-gluon plasma

    SciTech Connect (OSTI)

    Braun, Jens; Pirner, Hans-Juergen

    2007-03-01

    Finite temperature modifies the running of the QCD coupling {alpha}{sub s}(k,T) with resolution k. After calculating the thermal quark and gluon masses self-consistently, we determine the quark-quark and quark-gluon cross sections in the plasma based on the running coupling. We find that the running coupling enhances these cross sections by factors of two to four depending on the temperature. We also compute the energy loss (dE/dx) of a high-energy quark in the plasma as a function of temperature. Our study suggests that, beside t-channel processes, inverse Compton scattering is a relevant process for a quantitative understanding of the energy loss of an incident quark in a hot plasma.

  7. Chiral electric separation effect in the quark-gluon plasma

    SciTech Connect (OSTI)

    Jiang, Yin; Liao, Jinfeng; Huang, Xu-Guang

    2015-02-02

    In this paper we introduce and compute a new transport coefficient for the quark-gluon plasma (QGP) at very high temperature. This new coefficient ??e, the CESE (Chiral Electric Separation Effect) conductivity, quantifies the amount of axial current JA that is generated in response to an externally applied electric field eE: JA=??e(eE). Starting with a rather general argument in the kinetic theory framework, we show how a characteristic structure ??e???5 emerges, which also indicates the CESE as an anomalous transport effect occurring only in a parity-odd environment with nonzero axial charge density ?5 ? 0. Using the Hard-Thermal-Loop framework, the CESE conductivity for the QGP is found to be ??e = (#)TTrfQeQA/g?ln(1/g) ??5/T to the leading-log accuracy with the numerical constant (#) depending on favor content, e.g., (#)=14.5163 for u, d light flavors.

  8. Measurement of the W boson helicity in top quark decays

    SciTech Connect (OSTI)

    Gmyrek, Bryan David; /Arizona U.

    2007-08-01

    A measurement of the fraction, f{sup +}, of right-handed W bosons produced in top quark decays is presented. This analysis is based on a sample corresponding to an integrated luminosity of 370 pb{sup -1}, collected by the D0 detector at the Fermilab Tevatron p{bar p} Collider at {radical}s = 1.96 TeV. The helicity angle, {theta}*, is reconstructed for each lepton. f{sup +} is determined by comparing the cos {theta}* distribution from the data with that for the expected background and signal for various values of f{sup +}. The fraction of longitudinal W bosons, f{sup 0}, is assumed to be 0.7 as predicted by the standard model. This yields f{sup +} = 0.109 {+-} 0.094 (stat) {+-} 0.063 (syst), consistent with the standard model prediction of f{sup +} = 3.6x 10{sup -4}. The possibility that both f{sup +} and f{sup 0} stray from standard model values is also investigated. In this case cos {theta}* distributions for each possible W helicity state, along with the backgrounds, are fit to the cos {theta}* distribution for the data. The best fit values are f{sup +} = 0.82 {+-} 0.30(stat) and f{sup 0} = -0.58 {+-} 0.50(stat).

  9. Recent results on top quark physics at CDF

    SciTech Connect (OSTI)

    Gallinaro, M.; CDF Collaboration

    1997-01-01

    We present the latest results on the top quark obtained by the CDF experiment using a data sample of about 110 pb{sup -1}. The data sample has been collected at the FermiLab Tevatron Collider with p{anti p} collisions at {radical}s = 1.8 TeV. We briefly describe the candidate event selection and then discuss the production cross section determination and the mass measurement. Combining the results from the channels with at least one W decaying leptonically into an electron or muon, we measure {sigma}{sub t{anti t}} = 7.5{sup +1.9}{sub -1.6} pb. Our best measured value for the top mass gives M{sub t} = 176.8{+-}6.5 GeV/c{sup 2}. We also report on the observation of t{anti t} production in the all hadronic decay channel using kinematic selection and b identification, and in the channel containing one hadronically decaying {tau} lepton. Finally we discuss the kinematics of top events and measure the matrix element {vert_bar}V{sub tb}{vert_bar}=1.12{+-}0.12.

  10. Chiral electric separation effect in the quark-gluon plasma

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jiang, Yin; Liao, Jinfeng; Huang, Xu-Guang

    2015-02-02

    In this paper we introduce and compute a new transport coefficient for the quark-gluon plasma (QGP) at very high temperature. This new coefficient σχe, the CESE (Chiral Electric Separation Effect) conductivity, quantifies the amount of axial current JA that is generated in response to an externally applied electric field eE: JA=σχe(eE). Starting with a rather general argument in the kinetic theory framework, we show how a characteristic structure σχe∝μμ5 emerges, which also indicates the CESE as an anomalous transport effect occurring only in a parity-odd environment with nonzero axial charge density μ5 ≠ 0. Using the Hard-Thermal-Loop framework, the CESEmore » conductivity for the QGP is found to be σχe = (#)TTrfQeQA/g⁴ln(1/g) μμ5/T² to the leading-log accuracy with the numerical constant (#) depending on favor content, e.g., (#)=14.5163 for u, d light flavors.« less

  11. f{sub K}/f{sub {pi}} in full QCD with domain wall valence quarks (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect f{sub K}/f{sub {pi}} in full QCD with domain wall valence quarks Citation Details In-Document Search Title: f{sub K}/f{sub {pi}} in full QCD with domain wall valence quarks We compute the ratio of pseudoscalar decay constants f{sub K}/f{sub {pi}} using domain-wall valence quarks and rooted improved Kogut-Susskind sea quarks, at a lattice spacing of b{approx}0.125 fm. By employing continuum chiral perturbation theory, we extract the Gasser-Leutwyler low-energy

  12. Measurement of the Top Quark Mass Simultaneously in Dilepton and Lepton + Jets Decay Channels

    SciTech Connect (OSTI)

    Fedorko, Wojciech T.; /Chicago U.

    2008-09-01

    The authors present the first measurement of the top quark mass using simultaneously data from two decay channels. They use a data sample of {radical}s = 1.96 TeV collisions with integrated luminosity of 1.9 fb{sup -1} collected by the CDF II detector. They select dilepton and lepton + jets channel decays of t{bar t} pairs and reconstruct two observables in each topology. They use non-parametric techniques to derive probability density functions from simulated signal and background samples. The observables are the reconstructed top quark mass and the scalar sum of transverse energy of the event in the dilepton topology and the reconstructed top quark mass and the invariant mass of jets from the W boson decay in lepton + jets channel. They perform a simultaneous fit for the top quark mass and the jet energy scale which is constrained in situ by the hadronic W boson resonance from the lepton + jets channel. Using 144 dilepton candidate events and 332 lepton + jets candidate events they measure: M{sub top} = 171.9 {+-} 1.7 (stat. + JES) {+-} 1.1 (other sys.) GeV/c{sup 2} = 171.9 {+-} 2.0 GeV/c{sup 2}. The measurement features a robust treatment of the systematic uncertainties, correlated between the two channels and develops techniques for a future top quark mass measurement simultaneously in all decay channels. Measurements of the W boson mass and the top quark mass provide a constraint on the mass of the yet unobserved Higgs boson. The Higgs boson mass implied by measurement presented here is higher than Higgs boson mass implied by previously published, most precise CDF measurements of the top quark mass in lepton + jets and dilepton channels separately.

  13. Top-quark mass measurement using events with missing transverse energy and jets at CDF

    SciTech Connect (OSTI)

    Aaltonen, T; Alvarez Gonzalez, B; Amerio, S; Anastassov, A; Amidei, D; Antos, J; Annovi, A

    2013-07-01

    We present a measurement of the top-quark mass with tt? events using a data sample corresponding to an integrated luminosity of 5.7 fb -1 of pp? collisions at the Fermilab Tevatron with ?s = 1.96 TeV and collected by the CDF II Detector. We select events having no identified charged leptons, large missing transverse energy, and four, five, or six jets with at least one jet containing a secondary vertex consistent with the decay of a b quark. This analysis considers events from the semileptonic tt? decay channel, including events that contain tau leptons, which are usually not included in the top-quark mass measurements. The measurement uses as kinematic variables the invariant mass of two jets consistent with the mass of the W boson, and the invariant masses of two different three-jet combinations. We fit the data to signal templates of varying top-quark masses and background templates, and measure a top-quark mass of Mtop = 172.3 2.4 (stat) 1.0 (syst) GeV/c2.

  14. Measurement of single top quark production at D0 using a matrix element method

    SciTech Connect (OSTI)

    Mitrevski, Jovan Pavle; /Columbia U.

    2007-07-01

    Until now, the top quark has only been observed produced in pairs, by the strong force. According to the standard model, it can also be produced singly, via an electroweak interaction. Top quarks produced this way provide powerful ways to test the charged-current electroweak interactions of the top quark, to measure |V{sub tb}|, and to search for physics beyond the standard model. This thesis describes the application of the matrix element analysis technique to the search for single top quark production with the D0 detector using 0.9 fb{sup -1} of Run II data. From a comparison of the matrix element discriminants between data and the background model, assuming a Standard Model s-channel to t-channel cross section ratio of {sigma}{sub s}/{sigma}{sub t} = 0.44, we measure the single top quark production cross section: {sigma}(p{bar p} {yields} tb + X, tqb + X) = 4.8{sub -1.4}{sup +1.6} pb. This result has a p-value of 0.08%, corresponding to a 3.2 standard deviation Gaussian equivalent significance.

  15. Top-quark mass measurement using events with missing transverse energy and jets at CDF

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T.

    2011-11-30

    We present a measurement of the top-quark mass with tt̄ events using a data sample corresponding to an integrated luminosity of 5.7 fb -1 of pp̄ collisions at the Fermilab Tevatron with √s = 1.96 TeV and collected by the CDF II Detector. We select events having no identified charged leptons, large missing transverse energy, and four, five, or six jets with at least one jet containing a secondary vertex consistent with the decay of a b quark. This analysis considers events from the semileptonic tt̄ decay channel, including events that contain tau leptons, which are usually not included inmore » the top-quark mass measurements. The measurement uses as kinematic variables the invariant mass of two jets consistent with the mass of the W boson, and the invariant masses of two different three-jet combinations. We fit the data to signal templates of varying top-quark masses and background templates, and measure a top-quark mass of Mtop = 172.3 ± 2.4 (stat) ± 1.0 (syst) GeV/c2.« less

  16. Λb→pl⁻ν¯l form factors from lattice QCD with static b quarks

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Detmold, William; Lin, C.-J. David; Meinel, Stefan; Wingate, Matthew

    2013-07-23

    We present a lattice QCD calculation of form factors for the decay Λb→pμ⁻ν¯μ, which is a promising channel for determining the Cabibbo-Kobayashi-Maskawa matrix element |Vub| at the Large Hadron Collider. In this initial study we work in the limit of static b quarks, where the number of independent form factors reduces to two. We use dynamical domain-wall fermions for the light quarks, and perform the calculation at two different lattice spacings and at multiple values of the light-quark masses in a single large volume. Using our form factor results, we calculate the Λb→pμ⁻ν¯μ differential decay rate in the range 14more » GeV²≤q²≤q²max, and obtain the integral ∫q²max 14 GeV²[dΓ/dq²]dq²/|Vub|²=15.3±4.2 ps⁻¹. Combined with future experimental data, this will give a novel determination of |Vub| with about 15% theoretical uncertainty. The uncertainty is dominated by the use of the static approximation for the b quark, and can be reduced further by performing the lattice calculation with a more sophisticated heavy-quark action.« less

  17. {rho}{phi}{phi} and {omega}{omega} vertex functions within a confined quark model

    SciTech Connect (OSTI)

    Mitchell, K.; Tandy, P.C.

    1993-10-01

    We report results of an investigation of the p{pi}{pi} vertex function calculated from a quark including the distributed {anti q}q nature of the mesons. The quark propaagator is an entire function of the form recently extracie in a model confining Schwinger-Dyson equation. The parameters of the prop gator are chosen to fit {pi}{pi} scattering lengths. The dependence of the p{pi}{pi} vertex upon the p momentum is extracted the coupling constant is extracted at the mass shell point and compared to a previous approximation based at zero momentum. The model is extended to study the G-parity violating {omega}{pi}{pi} vertex produced by an up-down current quark mass difference. This is a possible contributing`mechanism for p-{omega} mixing.

  18. Search for pair production of the scalar top quark in the electron+muon final state

    SciTech Connect (OSTI)

    Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Alexeev, G.D.; Alkhazov, G.; Altona, A.; Alverson, G.; Alves, G.A.

    2010-09-01

    We report the result of a search for the pair production of the lightest supersymmetric partner of the top quark ({tilde t}{sub 1}) in p{bar p} collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider corresponding to an integrated luminosity of 5.4 fb{sup -1}. The scalar top quarks are assumed to decay into a b quark, a charged lepton, and a scalar neutrino ({tilde {nu}}), and the search is performed in the electron plus muon final state. No significant excess of events above the standard model prediction is detected, and improved exclusion limits at the 95% C.L. are set in the (M{sub {tilde t}{sub 1}}, M{sub {tilde {nu}}}) mass plane.

  19. Precise measurement of the top-quark mass from lepton+jets events at D0

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich

    2011-08-09

    We report a measurement of the mass of the top quark in lepton+jets final states of pp&3772; → tt̄ data corresponding to 2.6 fb-1 of integrated luminosity collected at the D0 experiment at the Fermilab Tevatron Collider. Using a matrix element method, we combine an in situ jet energy calibration with the standard jet energy scale derived in studies of Γ + jet and dijet events and employ a novel flavor-dependent jet response correction to measure a top-quark mass of mt = 176.01 ± 1.64 GeV. Combining this result with a previous result obtained on an independent data set, wemore » measure a top-quark mass of mt = 174.94 ± 1.49 GeV for a total integrated luminosity of 3.6 fb-1.« less

  20. Search for Single Vectorlike Quarks in pp? Collisions at ?s=1.96 TeV

    SciTech Connect (OSTI)

    Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G. A.; Ancu, L. S.; Aoki, M.; Arnoud, Y.; Arov, M.; Askew, A.; sman, B.; Atramentov, O.; Avila, C.; BackusMayes, J.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Beale, S.; Bean, A.; Begalli, M.; Begel, M.; Belanger-Champagne, C.; Bellantoni, L.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besanon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; Bolton, T. A.; Boos, E. E.; Borissov, G.; Bose, T.; Brandt, A.; Brandt, O.; Brock, R.; Brooijmans, G.; Bross, A.; Brown, D.; Brown, J.; Bu, X. B.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Burnett, T. H.; Buszello, C. P.; Calpas, B.; Camacho-Prez, E.; Carrasco-Lizarraga, M. A.; Casey, B. C. K.; Castilla-Valdez, H.; Caughron, S.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chen, G.; Chevalier-Thry, S.; Cho, D. K.; Cho, S. W.; Choi, S.; Choudhary, B.; Christoudias, T.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M.-C.; Croc, A.; Cutts, D.; ?wiok, M.; Das, A.; Davies, G.; De, K.; de Jong, S. J.; De La Cruz-Burelo, E.; Dliot, F.; Demarteau, M.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Dominguez, A.; Dorland, T.; Dubey, A.; Dudko, L. V.; Duggan, D.; Duperrin, A.; Dutt, S.; Dyshkant, A.; Eads, M.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Enari, Y.; Evans, H.; Evdokimov, A.; Evdokimov, V. N.; Facini, G.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Gadfort, T.; Garcia-Bellido, A.; Gavrilov, V.; Gay, P.; Geist, W.; Geng, W.; Gerbaudo, D.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Golovanov, G.; Goussiou, A.; Grannis, P. D.; Greder, S.; Greenlee, H.; Greenwood, Z. D.; Gregores, E. M.; Grenier, G.; Gris, Ph.; Grivaz, J.-F.; Grohsjean, A.; Grnendahl, S.; Grnewald, M. W.; Guo, F.; Gutierrez, G.; Gutierrez, P.; Haas, A.; Hagopian, S.; Haley, J.; Han, L.; Harder, K.; Harel, A.; Hauptman, J. M.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hoeneisen, B.; Hohlfeld, M.; Hossain, S.; Hubacek, Z.; Huske, N.; Hynek, V.; Iashvili, I.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffr, M.; Jain, S.; Jamin, D.; Jesik, R.; Johns, K.; Johnson, M.; Johnston, D.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Juste, A.; Kaadze, K.; Kajfasz, E.; Karmanov, D.; Kasper, P. A.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Khatidze, D.; Kirby, M. H.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kumar, A.; Kupco, A.; Kur?a, T.; Kuzmin, V. A.; Kvita, J.; Lammers, S.; Landsberg, G.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lellouch, J.; Li, L.; Li, Q. Z.; Lietti, S. M.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, Y.; Liu, Z.; Lobodenko, A.; Lokajicek, M.; Love, P.; Lubatti, H. J.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Mackin, D.; Madar, R.; Magaa-Villalba, R.; Malik, S.; Malyshev, V. L.; Maravin, Y.; Martnez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Meyer, A.; Meyer, J.; Mondal, N. K.; Muanza, G. S.; Mulhearn, M.; Nagy, E.; Naimuddin, M.; Narain, M.; Nayyar, R.; Neal, H. A.; Negret, J. P.; Neustroev, P.; Novaes, S. F.; Nunnemann, T.; Obrant, G.; Orduna, J.; Osman, N.; Osta, J.; Otero y Garzn, G. J.; Owen, M.; Padilla, M.; Pangilinan, M.; Parashar, N.; Parihar, V.; Park, S. K.; Parsons, J.; Partridge, R.; Parua, N.; Patwa, A.; Penning, B.; Perfilov, M.; Peters, K.; Peters, Y.; Petrillo, G.; Ptroff, P.; Piegaia, R.; Piper, J.; Pleier, M.-A.; Podesta-Lerma, P. L. M.; Podstavkov, V. M.; Pol, M.-E.; Polozov, P.; Popov, A. V.; Prewitt, M.; Price, D.; Protopopescu, S.; Qian, J.; Quadt, A.; Quinn, B.; Rangel, M. S.; Ranjan, K.; Ratoff, P. N.; Razumov, I.; Renkel, P.; Rich, P.; Rijssenbeek, M.; Ripp-Baudot, I.; Rizatdinova, F.; Rominsky, M.; Royon, C.; Rubinov, P.; Ruchti, R.; Safronov, G.; Sajot, G.; Snchez-Hernndez, A.; Sanders, M. P.; Sanghi, B.; Santos, A. S.; Savage, G.; Sawyer, L.; Scanlon, T.; Schamberger, R. D.; Scheglov, Y.; Schellman, H.; Schliephake, T.; Schlobohm, S.; Schwanenberger, C.; Schwienhorst, R.; Sekaric, J.; Severini, H.; Shabalina, E.; Shary, V.; Shchukin, A. A.; Shivpuri, R. K.; Simak, V.; Sirotenko, V.; Skubic, P.; Slattery, P.; Smirnov, D.

    2011-02-22

    We present a search for hypothetical vectorlike quarks in pp? collisions at ?s=1.96 TeV. The data were collected by the D0 detector at the Fermilab Tevatron Collider and correspond to an integrated luminosity of 5.4 fb?. We select events with a final state composed of a W or Z boson and a jet consistent with a heavy object decay. We observe no significant excess in comparison to the background prediction and set limits on production cross sections for vectorlike quarks decaying to W+jet and Z+jet. These are the most stringent limits to date for electroweak single vectorlike quark production at hadron colliders.

  1. Spectral-Fluctuations Test of the Quark-Model Baryon Spectrum

    SciTech Connect (OSTI)

    Fernandez-Ramirez, C.; Relano, A. [Instituto de Estructura de la Materia, CSIC, Serrano 123, E-28006 Madrid (Spain)

    2007-02-09

    We study the low-lying baryon spectrum (up to 2.2 GeV) provided by experiments and different quark models using statistical tools which allow us to postulate the existence of missing levels in spectra. We confirm that the experimental spectrum is compatible with random matrix theory, the paradigmatic model of quantum chaos, and we find that the quark models are more similar to a Poisson distribution, which is not compatible with what should be expected in a correlated spectrum. From our analysis it stems that the spectral fluctuation properties of quark-model spectra are incompatible with experimental data. This result can be used to enlighten the problem of missing resonances.

  2. Top quark rare three-body decays in the littlest Higgs model with T parity

    SciTech Connect (OSTI)

    Han Jinzhong; Li Bingzhong; Wang Xuelei

    2011-02-01

    In the littlest Higgs model with T-parity (LHT), the mirror quarks have flavor structures and will contribute to the top quark flavor changing neutral current. In this work, we perform an extensive investigation of the top quark rare three-body decays t{yields}cVV, (V={gamma}, Z, g) and t{yields}cff, (f=b, {tau}, {mu}, e) at one-loop level. Our results show that the branching ratios of t{yields}cgg and t{yields}cbb could reach O(10{sup -3}) in the favorite parameter space of the littlest Higgs model with T-parity, which implies that these decays may be detectable at the LHC or ILC, while for the other decays, their rates are too small to be observable at the present or future colliders.

  3. Precise measurement of the top-quark mass from lepton+jets events at D0

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich

    2011-08-09

    We report a measurement of the mass of the top quark in lepton+jets final states of pp&3772; → tt̄ data corresponding to 2.6 fb-1 of integrated luminosity collected at the D0 experiment at the Fermilab Tevatron Collider. Using a matrix element method, we combine an in situ jet energy calibration with the standard jet energy scale derived in studies of Γ + jet and dijet events and employ a novel flavor-dependent jet response correction to measure a top-quark mass of mt = 176.01 ± 1.64 GeV. Combining this result with a previous result obtained on an independent data set, wemore »measure a top-quark mass of mt = 174.94 ± 1.49 GeV for a total integrated luminosity of 3.6 fb-1.« less

  4. Electroproduction and gluonic production of J/{psi} mesons under the assumption of quark-hadron duality

    SciTech Connect (OSTI)

    Berezhnoy, A. V. Likhoded, A. K.

    2008-02-15

    On the basis of the assumption of quark-hadron duality, it is shown that the color-singlet contribution to the cross sections for the processes e + g {sup {yields}} e + J/{psi} + g and gg {sup {yields}} J/{psi}g increases upon taking into account the relative motion of quarks in the J/{psi} meson.

  5. Electroproduction and gluonic production of J/{psi} mesons under the assumption of quark-hadron duality

    SciTech Connect (OSTI)

    Berezhnoy, A. V.; Likhoded, A. K.

    2008-02-15

    On the basis of the assumption of quark-hadron duality, it is shown that the color-singlet contribution to the cross sections for the processes e + g {yields} e + J/{psi} + g and gg {yields} J/{psi}g increases upon taking into account the relative motion of quarks in the J/{psi} meson.

  6. Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at √s = 8 TeV with the ATLAS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.

    2015-08-20

    A search for pair production of vector-like quarks, both up-type (T) and down-type (B), as well as for four-top-quark production, is presented. The search is based on pp collisions at \\( \\sqrt{s}=8 \\) TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 20.3 fb–1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets. Dedicated analyses are performed targeting three cases: a T quark with significant branching ratio to a W bosonmore » and a b-quark \\( \\left(T\\overline{T}\\to Wb+\\mathrm{X}\\right) \\), and both a T quark and a B quark with significant branching ratio to a Higgs boson and a third-generation quark (\\( T\\overline{T}\\to Ht+X\\;\\mathrm{and}\\;B\\overline{B}\\to Hb+\\mathrm{X} \\) respectively). No significant excess of events above the Standard Model expectation is observed, and 95% CL lower limits are derived on the masses of the vector-like T and B quarks under several branching ratio hypotheses assuming contributions from T → Wb, Zt, Ht and B → Wt, Zb, Hb decays. The 95% CL observed lower limits on the T quark mass range between 715 GeV and 950 GeV for all possible values of the branching ratios into the three decay modes, and are the most stringent constraints to date. In addition, the most restrictive upper bounds on four-top-quark production are set in a number of new physics scenarios.« less

  7. Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at √s = 8 TeV with the ATLAS detector

    SciTech Connect (OSTI)

    Aad, G.

    2015-08-20

    A search for pair production of vector-like quarks, both up-type (T) and down-type (B), as well as for four-top-quark production, is presented. The search is based on pp collisions at \\( \\sqrt{s}=8 \\) TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 20.3 fb–1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets. Dedicated analyses are performed targeting three cases: a T quark with significant branching ratio to a W boson and a b-quark \\( \\left(T\\overline{T}\\to Wb+\\mathrm{X}\\right) \\), and both a T quark and a B quark with significant branching ratio to a Higgs boson and a third-generation quark (\\( T\\overline{T}\\to Ht+X\\;\\mathrm{and}\\;B\\overline{B}\\to Hb+\\mathrm{X} \\) respectively). No significant excess of events above the Standard Model expectation is observed, and 95% CL lower limits are derived on the masses of the vector-like T and B quarks under several branching ratio hypotheses assuming contributions from T → Wb, Zt, Ht and B → Wt, Zb, Hb decays. The 95% CL observed lower limits on the T quark mass range between 715 GeV and 950 GeV for all possible values of the branching ratios into the three decay modes, and are the most stringent constraints to date. In addition, the most restrictive upper bounds on four-top-quark production are set in a number of new physics scenarios.

  8. Binding Energies and Melting Temperatures of Heavy Hadrons in Quark-Gluon Plasma

    SciTech Connect (OSTI)

    Narodetskii, I. M.; Simonov, Yu. A.; Veselov, A. I.

    2011-05-23

    We discuss the consequences of the suggestion that the non-perturbative quark-antiquark potential at T{>=}T{sub c}, where T{sub c} is a temperature of a deconfinement phase transition in QCD can be studied through the modification of the correlation functions, which define the quadratic field correlators of the nonperturbative vaccuum fields. We use the non-perturbative quark-antiquark potential derived within the Field Correlator Method and the screened Coulomb potential with T-dependent Debye mass to calculate J/{psi}, {Upsilon} and {Omega}{sub bbb} binding energies and melting temperatures in the deconfined phase of QCD.

  9. Stopping distance for high energy jets in weakly coupled quark-gluon plasmas

    SciTech Connect (OSTI)

    Arnold, Peter; Cantrell, Sean; Xiao Wei

    2010-02-15

    We derive a simple formula for the stopping distance for a high-energy quark traveling through a weakly coupled quark-gluon plasma. The result is given to next-to-leading order in an expansion in inverse logarithms ln(E/T), where T is the temperature of the plasma. We also define a stopping distance for gluons and give a leading-log result. Discussion of stopping distance has a theoretical advantage over discussion of energy loss rates in that stopping distances can be generalized to the case of strong coupling, where one may not speak of individual partons.

  10. Color-singlet clustering of partons and recombination model for hadronization of quark-gluon plasma

    SciTech Connect (OSTI)

    Abir, Raktim; Mustafa, Munshi G.

    2009-11-15

    SU(N{sub c}) color-singlet restriction, along with flavor and spin symmetry, on a thermal partonic ensemble is shown to recombine the partons with internal color structure into color-singlet multiquark clusters, which can be identified with various hadronic modes at a given temperature. This can provide a possible basis for a recombination model for hadronization of quark-gluon plasma. This also leads to a natural explanation for the ratio of (anti)protons to pions and the quark number scaling of the elliptic flow coefficient in relativistic heavy-ion collisions.

  11. High-energy jet quenching in weakly coupled quark-gluon plasmas

    SciTech Connect (OSTI)

    Arnold, Peter; Xiao Wei

    2008-12-15

    q is the average squared transverse momentum transfer per unit length to a high-energy particle traversing a QCD medium such as a quark-gluon plasma. We find the (UV-regulated) value of q to leading order in the weak coupling limit, {alpha}{sub s}(T)<<1. We then use this value to generalize previous analytic results on the gluon bremsstrahlung and pair production rates for massless high-energy particles in a weakly coupled quark-gluon plasma, at next-to-leading logarithmic order.

  12. Fluctuations driven isotropization of the quark-gluon plasma in heavy ion collisions

    SciTech Connect (OSTI)

    Akkelin, S. V.

    2008-07-15

    Averaged over ensemble of initial conditions kinetic transport equations of weakly coupled systems of quarks and gluons are derived. These equations account for the correlators of fluctuations of particles and classical gluon fields. The isotropization of particle momenta by field fluctuations at the early prethermal stage of matter evolution in ultrarelativistic heavy ion collisions is discussed. Our results can be useful for understanding under what conditions isotropization of the quark-gluon plasma in ultrarelativistic heavy ion collisions can be reached within phenomenologically observed time scales.

  13. Electroweak production of top-quark pairs in e + e - annihilation at NNLO

    Office of Scientific and Technical Information (OSTI)

    in QCD: The vector current contributions (Journal Article) | SciTech Connect Electroweak production of top-quark pairs in e + e - annihilation at NNLO in QCD: The vector current contributions Citation Details In-Document Search Title: Electroweak production of top-quark pairs in e + e - annihilation at NNLO in QCD: The vector current contributions Authors: Gao, Jun ; Zhu, Hua Xing Publication Date: 2014-12-17 OSTI Identifier: 1180238 Grant/Contract Number: SC0003870; DEAC0276SF00515 Type:

  14. Geek-Up[12.03.2010]: Halomonadaceae Bacteria and the Return of Quark Gluon

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Plasma | Department of Energy 03.2010]: Halomonadaceae Bacteria and the Return of Quark Gluon Plasma Geek-Up[12.03.2010]: Halomonadaceae Bacteria and the Return of Quark Gluon Plasma December 3, 2010 - 4:59pm Addthis Niketa Kumar Niketa Kumar Public Affairs Specialist, Office of Public Affairs As a fellow geek, you probably heard NASA's big news yesterday. If not, here's a recap: It was once assumed that all life on Earth, from humans and giraffes to scorpions and plankton, are all based on

  15. Four fermion operator matching with nonrelativistic QCD heavy and asqtad light quarks

    SciTech Connect (OSTI)

    Gamiz, Elvira; Shigemitsu, Junko; Trottier, Howard

    2008-06-01

    We present one-loop matching coefficients between continuum and lattice QCD for the heavy-light four-fermion operators relevant for neutral B meson mixing both within and beyond the standard model. For the lattice theory we use nonrelativistic QCD (NRQCD) to describe b quarks and improved staggered fermions (AsqTad) for light quarks. The gauge action is the tree-level Symanzik improved gauge action. Matching to full QCD is carried out through order {alpha}{sub s}, {lambda}{sub QCD}/M{sub b}, and {alpha}{sub s}/(aM{sub b})

  16. Charm-Quark Production in Deep-Inelastic Neutrino Scattering at

    Office of Scientific and Technical Information (OSTI)

    Next-to-Next-to-Leading Order in QCD (Journal Article) | SciTech Connect Charm-Quark Production in Deep-Inelastic Neutrino Scattering at Next-to-Next-to-Leading Order in QCD Citation Details In-Document Search This content will become publicly available on May 24, 2017 Title: Charm-Quark Production in Deep-Inelastic Neutrino Scattering at Next-to-Next-to-Leading Order in QCD Authors: Berger, Edmond L. ; Gao, Jun ; Li, Chong Sheng ; Liu, Ze Long ; Zhu, Hua Xing Publication Date: 2016-05-24

  17. Search for single production of a vector-like quark via a heavy gluon in

    Office of Scientific and Technical Information (OSTI)

    the 4b final state with the ATLAS detector in pp collisions at s=8 TeV (Journal Article) | SciTech Connect single production of a vector-like quark via a heavy gluon in the 4b final state with the ATLAS detector in pp collisions at s = 8 TeV Citation Details In-Document Search Title: Search for single production of a vector-like quark via a heavy gluon in the 4b final state with the ATLAS detector in pp collisions at s = 8 TeV Publication Date: 2016-07-01 OSTI Identifier: 1252315 Type:

  18. Measurement of the top quark mass in lepton+jets events with secondary vertex tagging

    SciTech Connect (OSTI)

    Harrington, Robert Duane; /Northeastern U.

    2007-02-01

    A measurement of the top quark mass with the matrix element method in the lepton + jets final state in D0 Run II is presented. Events with single isolated energetic charged lepton (electron or muon), exactly four calorimeter jets, and significant missing transverse energy are selected. Probabilities used to discriminate between signal and background are assumed to be proportional to differential cross-sections, calculated using event kinematics and folding in object resolutions and parton distribution functions. The event likelihoods constructed using these probabilities are varied with the top quark mass, m{sub t}, and the jet energy scale, JES, to give the smallest possible combined statistical + JES uncertainty.

  19. Up and Down Quarks Favored Over Strange Ones | U.S. DOE Office of Science

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    (SC) Up and Down Quarks Favored Over Strange Ones Nuclear Physics (NP) NP Home About Research Facilities Science Highlights Benefits of NP Funding Opportunities Nuclear Science Advisory Committee (NSAC) Community Resources Contact Information Nuclear Physics U.S. Department of Energy SC-26/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-3613 F: (301) 903-3833 E: Email Us More Information » 08.01.15 Up and Down Quarks Favored Over Strange Ones The proton's

  20. Top Quark Forward-Backward Asymmetry in e + e - Annihilation at

    Office of Scientific and Technical Information (OSTI)

    Next-to-Next-to-Leading Order in QCD (Journal Article) | SciTech Connect Top Quark Forward-Backward Asymmetry in e + e - Annihilation at Next-to-Next-to-Leading Order in QCD Citation Details In-Document Search Title: Top Quark Forward-Backward Asymmetry in e + e - Annihilation at Next-to-Next-to-Leading Order in QCD Authors: Gao, Jun ; Zhu, Hua Xing Publication Date: 2014-12-31 OSTI Identifier: 1180004 Grant/Contract Number: AC02-06CH11357; AC02-76SF00515 Type: Publisher's Accepted

  1. Top-Quark Decay at Next-to-Next-to-Leading Order in QCD (Journal Article) |

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Journal Article: Top-Quark Decay at Next-to-Next-to-Leading Order in QCD Citation Details In-Document Search Title: Top-Quark Decay at Next-to-Next-to-Leading Order in QCD Authors: Gao, Jun ; Li, Chong Sheng ; Zhu, Hua Xing Publication Date: 2013-01-24 OSTI Identifier: 1101939 Type: Publisher's Accepted Manuscript Journal Name: Physical Review Letters Additional Journal Information: Journal Volume: 110; Journal Issue: 4; Journal ID: ISSN 0031-9007 Publisher: American Physical

  2. Search for pair production of scalar top quarks decaying to a tau lepton and a b quark in 1.96 TeV ppbar collisions

    SciTech Connect (OSTI)

    Khotilovich, Vadim, G.; /Texas A-M

    2008-05-01

    I present the results of a search for pair production of scalar top quarks ({tilde t}{sub 1}) in an R-parity violating supersymmetric scenario using 322 pb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV collected by the upgraded Collider Detector at Fermilab. I assume each {tilde t}{sub 1} decays into a {tau} lepton and a b quark, with branching ratio {beta}, and search for final states containing either an electron or a muon from a leptonic {tau} decay, a hadronically decaying {tau} lepton, and two or more jets. Two candidate events pass my final selection criteria, consistent with the expectation from standard model processes. I present upper limits on the cross section times branching ratio squared {sigma}({tilde t}{sub 1}{bar {tilde t}}{sub 1}) x {beta}{sup 2} as a function of the stop mass m({tilde t}{sub 1}). Assuming {beta} = 1, I set a 95% confidence level limit m({tilde t}{sub 1}) > 153 GeV=c{sup 2}. These limits are also fully applicable to the case of a pair produced third generation scalar leptoquark that decays into a {tau} lepton and a b quark.

  3. Measurement of cross section of quark pair production top with the D0 experiment at the Tevatron and determination the top quark mass using this measure

    SciTech Connect (OSTI)

    Chevalier-Thery, Solene; /Paris U., VI-VII /Saclay

    2010-06-01

    The top quark has been discovered by CDF and D0 experiments in 1995 at the proton-antiproton collider Tevatron. The amount of data recorded by both experiments makes it possible to accurately study the properties of this quark: its mass is now known to better than 1% accuracy. This thesis describes the measurement of the top pair cross section in the electron muon channel with 4, 3 fb{sup -1} recorded data between 2006 and 2009 by the D0 experiment. Since the final state included a muon, improvements of some aspects of its identification have been performed : a study of the contamination of the cosmic muons and a study of the quality of the muon tracks. The cross section measurement is in good agreement with the theoretical calculations and the other experimental measurements. This measurement has been used to extract a value for the top quark mass. This method allows for the extraction of a better defined top mass than direct measurements as it depends less on Monte Carlo simulations. The uncertainty on this extracted mass, dominated by the experimental one, is however larger than for direct measurements. In order to decrease this uncertainty, the ratio of the Z boson and the top pair production cross sections has been studied to look for some possible theoretical correlations. At the Tevatron, the two cross sections are not theoretically correlated: no decrease of the uncertainty on the extracted top mass is therefore possible.

  4. Search for pair production of the scalar top quark in muon plus tau final states

    SciTech Connect (OSTI)

    Abazov V. M.; Abbott B.; Acharya B. S.; Adams M.; Adams T.; Alexeev G. D.; Alkhazov G.; Alton A.; Alverson G.; Aoki M.; Askew A.; Asman B.; Atkins S.; Atramentov O.; Augsten K.; Avila C.; BackusMayes J.; Badaud F.; Bagby L.; Baldin B.; Bandurin D. V.; Banerjee S.; Barberis E.; Baringer P.; Barreto J.; Bartlett J. F.; Bassler U.; Bazterra V.; Bean A.; Begalli M.; Belanger-Champagne C.; Bellantoni L.; Beri S. B.; Bernardi G.; Bernhard R.; Bertram I.; Besancon M.; Beuselinck R.; Bezzubov V. A.; Bhat P. C.; Bhatia S.; Bhatnagar V.; Blazey G.; Blessing S.; Bloom K.; Boehnlein A.; Boline D.; Boos E. E.; Borissov G.; Bose T.; Brandt A.; Brandt O.; Brock R.; Brooijmans G.; Bross A.; Brown D.; Brown J.; Bu X. B.; Buehler M.; Buescher V.; Bunichev V.; Burdin S.; Burnett T. H.; Buszello C. P.; Calpas B.; Camacho-Perez E.; Carrasco-Lizarraga M. A.; Casey B. C. K.; Castilla-Valdez H.; Chakrabarti S.; Chakraborty D.; Chan K. M.; Chandra A.; Chapon E.; Chen G.; Chevalier-Thery S.; Cho D. K.; Cho S. W.; Choi S.; Choudhary B.; Cihangir S.; Claes D.; Clutter J.; Cooke M.; Cooper W. E.; Corcoran M.; Couderc F.; Cousinou M. -C.; Croc A.; Cutts D.; Das A.; Davies G.; de Jong S. J.; De La Cruz-Burelo E.; Deliot F.; Demina R.; Denisov D.; Denisov S. P.; Desai S.; Deterre C.; DeVaughan K.; Diehl H. T.; Diesburg M.; Ding P. F.; Dominguez A.; Dorland T.; Dubey A.; Dudko L. V.; Duggan D.; Duperrin A.; Dutt S.; Dyshkant A.; Eads M.; Edmunds D.; Ellison J.; Elvira V. D.; Enari Y.; Evans H.; Evdokimov A.; Evdokimov V. N.; Facini G.; Ferbel T.; Fiedler F.; Filthaut F.; Fisher W.; Fisk H. E.; Fortner M.; Fox H.; Fuess S.; Garcia-Bellido A.; Garcia-Guerra G. A.; Gavrilov V.; Gay P.; Geng W.; Gerbaudo D.; Gerber C. E.; Gershtein Y.; Ginther G.; Golovanov G.; Goussiou A.; Grannis P. D.; Greder S.; Greenlee H.; Greenwood Z. D.; Gregores E. M.; Grenier G.; Gris Ph.; Grivaz J. -F.; Grohsjean A.; Gruenendahl S.; Gruenewald M. W.; Guillemin T.; Gutierrez G.; Gutierrez P.; Haas A.; Hagopian S.; Haley J.; Han L.; Harder K.; Harel A.; Hauptman J. M.; Hays J.; Head T.; Hebbeker T.; Hedin D.; Hegab H.; Heinson A. P.; Heintz U.; Hensel C.; Heredia-De La Cruz I.; Herner K.; Hesketh G.; Hildreth M. D.; Hirosky R.; Hoang T.; Hobbs J. D.; Hoeneisen B.; Hohlfeld M.; Hubacek Z.; Hynek V.; Iashvili I.; Ilchenko Y.; Illingworth R.; Ito A. S.; Jabeen S.; Jaffre M.; Jamin D.; Jayasinghe A.; Jesik R.; Johns K.; Johnson M.; Jonckheere A.; Jonsson P.; Joshi J.; Jung A. W.; Juste A.; Kaadze K.; Kajfasz E.; Karmanov D.; Kasper P. A.; Katsanos I.; Kehoe R.; Kermiche S.; Khalatyan N.; Khanov A.; Kharchilava A.; Kharzheev Y. N.; Kohli J. M.; Kozelov A. V.; Kraus J.; Kulikov S.; Kumar A.; Kupco A.; Kurca T.; Kuzmin V. A.; Lammers S.; Landsberg G.; Lebrun P.; Lee H. S.; Lee S. W.; Lee W. M.; Lellouch J.; Li H.; Li L.; Li Q. Z.; Lietti S. M.; Lim J. K.; Lincoln D.; Linnemann J.; Lipaev V. V.; Lipton R.; Liu Y.; Lobodenko A.; Lokajicek M.; Lopes de Sa R.; Lubatti H. J.; Luna-Garcia R.; Lyon A. L.; Maciel A. K. A.; Mackin D.; Madar R.; Magana-Villalba R.; Malik S.; Malyshev V. L.; Maravin Y.; Martinez-Ortega J.; McCarthy R.; McGivern C. L.; Meijer M. M.; Melnitchouk A.; Menezes D.; Mercadante P. G.; Merkin M.; et al.

    2012-04-20

    We present a search for the pair production of scalar top quarks ({tilde t}{sub 1}), the lightest supersymmetric partners of the top quarks, in p{bar p} collisions at a center-of-mass energy of 1.96 TeV, using data corresponding to an integrated luminosity of 7.3 fb{sup -1} collected with the D0 experiment at the Fermilab Tevatron Collider. Each scalar top quark is assumed to decay into a b quark, a charged lepton, and a scalar neutrino ({tilde {nu}}). We investigate final states arising from {tilde t}{sub 1}{ovr {tilde t}{sub 1}} {yields} b{bar b}{mu}{tau}{tilde {nu}}{tilde {nu}} and {tilde t}{sub 1}{ovr {tilde t}{sub 1}} {yields} b{bar b}{tau}{tau}{tilde {nu}}{tilde {nu}}. With no significant excess of events observed above the background expected from the standard model, we set exclusion limits on this production process in the (M{sub {tilde t}{sub 1}}, M{sub {tilde {nu}}}) plane.

  5. Study of the top quark electric charge at the CDF experiment

    SciTech Connect (OSTI)

    Bartos, Pavol; /Comenius U.

    2011-09-01

    We report on the measurement of the top quark electric charge using the jet charge tagging method on events containing a single lepton collected by the CDF II detector at Fermilab between February 2002 and February 2010 at the center-of-mass energy {radical}s = 1.96 TeV. There are three main components to this measurement: determining the charge of the W (using the charge of the lepton), pairing the W with the b-jet to ensure that they are from the same top decay branch and finally determining the charge of the b-jet using the Jet Charge algorithm. We found, on a sample of 5.6 fb{sup -1} of data, that the p-value under the standard model hypothesis is equal to 13.4%, while the p-value under the exotic model hypothesis is equal to 0.014%. Using the a priori criteria generally accepted by the CDF collaboration, we can say that the result is consistent with the standard model, while we exclude an exotic quark hypothesis with 95% confidence. Using the Bayesian approach, we obtain for the Bayes factor (2ln(BF)) a value of 19.6, that favors very strongly the SM hypothesis over the XM one. The presented method has the highest sensitivity to the top quark electric charge among the presented so far top quark charge analysis.

  6. Charm diffusion in a pion gas implementing unitarity, chiral and heavy quark symmetries

    SciTech Connect (OSTI)

    Abreu, Luciano M.; Cabrera, Daniel; Llanes-Estrada, Felipe J.; Torres-Rincon, Juan M.

    2011-10-15

    We compute the charm drag and diffusion coefficients in a hot pion gas, such as is formed in a heavy ion collision after the system cools sufficiently to transit into the hadron phase. We fully exploit heavy quark effective theory (with both D and D{sup *} mesons as elementary degrees of freedom during the collision) and chiral perturbation theory, and employ standard unitarization to reach higher temperatures. We find that a certain friction and shear diffusion coefficients are almost p{sup 2}-independent at a fixed temperature which simplifies phenomenological analysis. At the higher end of reliability of our calculation, T{approx_equal}150MeV, we report a charm relaxation length {lambda}{sub c}{approx_equal}40fm, in agreement with the model estimate of He, Fries and Rapp. The momentum of a 1 GeV charm quark decreases about 50 MeV per fermi when crossing the hadron phase. - Highlights: > We compute charm drag and diffusion in a pion gas (in heavy ion collisions). > We employ effective theory (both chiral and heavy quark). > We unitarize the perturbative amplitude for realistic cross-sections. > A charm quark with momentum 1 GeV loses 50 MeV per fermi (drag). > The momentum distribution broadens some 100 MeV per fermi (diffusion).

  7. Exploiting Third Generation Quarks for New Physics Discoveries at the Energy Frontier

    SciTech Connect (OSTI)

    Ivanov, Andrew G.

    2013-10-15

    The K-State group's effort is top quark physics and searches for beyond-standard-model physics in t{anti #22;}t final states. The KSU team performed the most precise measurement of the t#22;{anti t} cross section in the lepton + jets channel, and for the first time excluded the fourth generation of the standard model in the perturbative regime.

  8. How do quarks and gluons lose energy in the QGP?

    SciTech Connect (OSTI)

    Tannenbaum, M. J.

    2015-03-10

    RHIC introduced the method of hard scattering of partons as an in-situ probe of the the medium produced in A+A collisions. A suppression, RAA ? 0.2 relative to binary-scaling, was discovered for ?? production in the range 5 < ?T < 20 GeV/c in central Au+Au collisions at ?sNN = 200 GeV, and surprisingly also for single-electrons from the decay of heavy quarks. Both these results have been confirmed in Pb+Pb collisions at the LHC at ?sNN = 2.76 TeV. Interestingly, in this ?T range the LHC results for pions nearly overlap the RHIC results. Thus, due to the flatter spectrum, the energy loss in the medium at LHC in this ?T range must be ~ 40% larger than at RHIC. Unique at the LHC are the beautiful measurements of the fractional transverse momentum imbalance 1 (?-carotT2/?-carotT1) of di-jets in Pb+Pb collisions. At the Utrecht meeting in 2011, I corrected for the fractional imbalance of di-jets with the same cuts in p-p collisions and showed that the relative fractional jet imbalance in Pb+Pb/p-p is ? 15% for jets with 120 < ?-carotT1 < 360 GeV/c. CMS later confirmed this much smaller imbalance compared to the same quantity derived from two-particle correlations of di-jet fragments at RHIC corresponding to ?-carotT jet ? 10 20 GeV/c, which appear to show a much larger fractional jet imbalance ? 45% in this lower ?-carotT range. The variation of apparent energy loss in the medium as a function of both ?T and ?sNN is striking and presents a challenge to both theory and experiment for improved understanding. There are many other such unresolved issues, for instance, the absence of evidence for a q-carot effect, due to momentum transferred to the medium by outgoing partons, which would widen the away-side di-jet and di-hadron correlations in a similar fashion as the kT-effect. Another issue well known from experiments at the CERN ISR, SpS and SpS collider is that parton-parton hard-collisions make negligible contribution to multiplicity or transverse energy production in p-p collisionssoft particles, with ?T < 2 GeV/c, predominate. Thus an apparent hard scattering component for A+A multiplicity distributions based on a popular formula, dNAAch/d? = [(1 - x) (Npart)dNppch/d?2 + x (NcolldNppch/d?], seems to be an unphysical way to understand the deviation from Npart scaling. Based on recent p-p and d+A measurements, a more physical way is presented along with several other stimulating results and ideas from recent d+Au (p+Pb) measurements.

  9. How do quarks and gluons lose energy in the QGP?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tannenbaum, M. J.

    2015-03-10

    RHIC introduced the method of hard scattering of partons as an in-situ probe of the the medium produced in A+A collisions. A suppression, RAA ≈ 0.2 relative to binary-scaling, was discovered for π⁰ production in the range 5 < ρT < 20 GeV/c in central Au+Au collisions at √sNN = 200 GeV, and surprisingly also for single-electrons from the decay of heavy quarks. Both these results have been confirmed in Pb+Pb collisions at the LHC at √sNN = 2.76 TeV. Interestingly, in this ρT range the LHC results for pions nearly overlap the RHIC results. Thus, due to the flattermore » spectrum, the energy loss in the medium at LHC in this ρT range must be ~ 40% larger than at RHIC. Unique at the LHC are the beautiful measurements of the fractional transverse momentum imbalance 1 – (ρ-carotT2/ρ-carotT1) of di-jets in Pb+Pb collisions. At the Utrecht meeting in 2011, I corrected for the fractional imbalance of di-jets with the same cuts in p-p collisions and showed that the relative fractional jet imbalance in Pb+Pb/p-p is ≈ 15% for jets with 120 < ρ-carotT1 < 360 GeV/c. CMS later confirmed this much smaller imbalance compared to the same quantity derived from two-particle correlations of di-jet fragments at RHIC corresponding to ρ-carotT jet ≈ 10 – 20 GeV/c, which appear to show a much larger fractional jet imbalance ≈ 45% in this lower ρ-carotT range. The variation of apparent energy loss in the medium as a function of both ρT and √sNN is striking and presents a challenge to both theory and experiment for improved understanding. There are many other such unresolved issues, for instance, the absence of evidence for a q-carot effect, due to momentum transferred to the medium by outgoing partons, which would widen the away-side di-jet and di-hadron correlations in a similar fashion as the kT-effect. Another issue well known from experiments at the CERN ISR, SpS and SpS collider is that parton-parton hard-collisions make negligible contribution to multiplicity or transverse energy production in p-p collisions–soft particles, with ρT < 2 GeV/c, predominate. Thus an apparent hard scattering component for A+A multiplicity distributions based on a popular formula, dNAAch/dη = [(1 - x) (Npart)dNppch/dη2 + x (NcolldNppch/dη], seems to be an unphysical way to understand the deviation from Npart scaling. Based on recent p-p and d+A measurements, a more physical way is presented along with several other stimulating results and ideas from recent d+Au (p+Pb) measurements.« less

  10. A Search for scalar bottom quarks from gluino decays in anti-p p collisions at s**(1/2) = 1.96-TeV

    SciTech Connect (OSTI)

    Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G.; Ambrose, D.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; /Taiwan, Inst. Phys. /Argonne /Barcelona, IFAE /Baylor U. /INFN, Bologna /Bologna U. /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara

    2005-12-01

    We searched for scalar bottom quarks in 156 pb{sup -1} of {bar p}p collisions at {radical}s = 1.96 TeV recorded by the CDF II experiment at the Tevatron. Scalar bottom quarks can be produced from gluino decays in R-parity conserving models of supersymmetry when the mass of the gluino exceeds that of the scalar bottom quark. Then, a scalar bottom quark can decay into a bottom quark and a neutralino. To search for this scenario, we investigated events with large missing transverse energy and at least three jets, two or more of which were identified as containing a secondary vertex from the hadronization of b quarks. We found four candidate events, where 2.6 {+-} 0.7 are expected from standard model processes, and placed 95% confidence level lower limits on gluino and scalar bottom quark masses of up to 280 and 240 GeV/c{sup 2} , respectively.

  11. Flavor diagonal and off-diagonal susceptibilities in a quasiparticle model of the quark-gluon plasma

    SciTech Connect (OSTI)

    Bluhm, M.; Kaempfer, B.

    2008-06-01

    The Taylor coefficients of flavor diagonal and off-diagonal susceptibilities as well as baryon number, isovector, and electric charge susceptibilities are considered within a phenomenological quasiparticle model of the quark-gluon plasma and successfully compared with available lattice QCD data up to fourth-order for two degenerate quark flavors. These susceptibility coefficients represent sensible probes of baryon-density effects in the equation of state. The baryon charge is carried, in our model, by quark-quasiparticle excitations for hard momenta.

  12. Study on the top quark pair production mechanism in 1.96 TeV proton-antiproton collisions

    SciTech Connect (OSTI)

    Naganoma, Junji; /Waseda U.

    2008-03-01

    The study of the top quark pair production mechanism in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV is described. The main subjects are the measurements of the top quark pair production cross section, the top quark mass and a search for a new particle decaying to the top quark pair. The analyses are based on 1.9 fb{sup -1} of data collected by the Collider Detector at Fermilab (CDF) Run II experiment between March 2002 and May 2007, using the lepton+jets events. The measured top quark pair production cross section is 8.2 {+-} 0.5 (stat.) {+-} 0.8 (syst.) {+-} 0.5 (lum.) pb, which is slightly higher than the standard model prediction at the top mass of 175 GeV/c{sup 2}. The top quark mass is an important parameter in the standard model, and also in the experimental studies. The measured top quark mass if 171.6 {+-} 2.0 (stat.) {+-} 1.3(syst.) GeV/c{sup 2}. Finally, they report on a search for a new gauge boson decaying to t{bar t}, which interferes with the standard model gluon in the q{bar q} {yields} t{bar t} production process. They call such a hypothetical particle a 'Massive Gluon'. The observed t{bar t} invariant mass distribution is consistent with the standard model expectations, and also the measured massive gluon coupling strength with quarks is consistent within a statistical fluctuation of the standard model expectation in the wide range of the massive gluon masses and widths. They set the upper and lower limits on the coupling strength of the massive gluon.

  13. Spatially Modulated Phase in the Holographic Description of Quark-Gluon Plasma

    SciTech Connect (OSTI)

    Ooguri, Hirosi; Park, Chang-Soon

    2011-02-11

    We present a string theory construction of a gravity dual of a spatially modulated phase. Our earlier work shows that the Chern-Simons term in the five-dimensional Maxwell theory destabilizes the Reissner-Nordstroem black holes in anti-de Sitter space if the Chern-Simons coupling is sufficiently high. In this Letter, we show that a similar instability is realized on the world volume of 8-branes in the Sakai-Sugimoto model in the quark-gluon plasma phase. Our result suggests a new spatially modulated phase in quark-gluon plasma when the baryon density is above 0.8N{sub f} fm{sup -3} at temperature 150 MeV.

  14. Evolution of collectivity as a signal of quark gluon plasma formation in heavy ion collisions

    SciTech Connect (OSTI)

    Mohanty, Payal; Alam, Jan-e; Mohanty, Bedangadas

    2011-08-15

    A measurement for studying the mass dependence of dilepton interferometry in relativistic heavy-ion collision experiments as a tool to characterize the quark gluon phase is proposed. In calculations involving dileptons, we show that the mass dependence of radii extracted from the virtual photon (dilepton) interferometry provide access to the development of collective flow with time. It is argued that the nonmonotonic variation of Hanbury Brown-Twiss radii with invariant mass of the lepton pairs signals the formation of quark gluon plasma in heavy ion collisions. Our proposal of experimentally measuring the ratio, R{sub out}/R{sub side} for dileptons can be used to estimate the average lifetimes of the partonic as well as the hadronic phases.

  15. Momentum broadening of a fast parton in a perturbative quark-gluon plasma

    SciTech Connect (OSTI)

    Majumder, Abhijit; Mueller, Berndt; Mrowczynski, Stanislaw

    2009-12-15

    The average transverse momentum transfer per unit path length to a fast parton scattering elastically in a perturbative quark-gluon plasma is related to the radiative energy loss of the parton. We first calculate the momentum transfer coefficient q-circumflex in terms of a classical Langevin problem and then define it quantum mechanically through a scattering matrix element. After treating the well-known case of a quark-gluon plasma in equilibrium, we consider an off-equilibrium unstable plasma. As a specific example, we treat the two-stream plasma with unstable modes of longitudinal chromoelectric field. In the presence of the instabilities, q-circumflex is shown to exponentially grow in time.

  16. Rare top quark and Higgs boson decays in alternative left-right symmetric models

    SciTech Connect (OSTI)

    Gaitan, R.; Miranda, O.G.; Cabral-Rosetti, L.G.

    2005-08-01

    Top quark and Higgs boson decays induced by flavor-changing neutral currents (FCNC) are very much suppressed in the standard model. Their detection in colliders such as the Large Hadron Collider, Next Linear Collider, or Tevatron would be a signal of new physics. We evaluate the FCNC decays t{yields}H{sup 0}+c, t{yields}Z+c, and H{sup 0}{yields}t+c in the context of alternative left-right symmetric models with extra isosinglet heavy fermions; in this case, FCNC decays occur at tree level, and they are suppressed only by the mixing between ordinary top and charm quarks, which is poorly constrained by current experimental values. This provides the possibility for future colliders either to detect new physics or to improve present bounds on the parameters of the model.

  17. Precision measurement of the top-quark mass in lepton+jets final states

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich

    2014-07-17

    We measure the mass of the top quark in lepton$+$jets final states using the full sample of $p\\bar{p}$ collision data collected by the D0 experiment in Run II of the Fermilab Tevatron Collider at $\\sqrt s=1.96 $TeV, corresponding to $9.7 {\\rm fb}^{-1}$ of integrated luminosity. We use a matrix element technique that calculates the probabilities for each event to result from $t\\bar t$ production or background. The overall jet energy scale is constrained in situ by the mass of the $W$ boson. We measure $m_t=174.98\\pm0.76$ GeV. In conclusion, this constitutes the most precise single measurement of the top-quark mass.

  18. Precision measurement of the top-quark mass in lepton$+$jets final states

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich

    2015-06-04

    We measure the mass of the top quark in lepton þ jets final states using the full sample of pp¯ collision data collected by the D0 experiment in Run II of the Fermilab Tevatron Collider at √s = 1.96 TeV, corresponding to 9.7 fb-1 of integrated luminosity. We also use a matrix element technique that calculates the probabilities for each event to result from tt¯ production or background. Furthermore, the overall jet energy scale is constrained in situ by the mass of the W boson. We measure mt = 174.98 ± 0.76 GeV. As a result, this constitutes the mostmore » precise single measurement of the top-quark mass.« less

  19. Measurement of the helicity of W bosons in top-quark decays

    SciTech Connect (OSTI)

    Abulencia, A. et al

    2006-06-01

    We measure the branching fraction of the top quark to longitudinally and right-handed polarized W bosons, F{sub 0} and F{sub +}, using approximately 200 pb{sup -1} of p{bar p} collisions collected by the CDF II detector. We analyze two quantities sensitive to the W helicity: the invariant mass of the charged lepton and the bottom-quark jet in the decay t {yields} Wb {yields} {ell}{nu}b (where {ell} = e or {mu}), and the transverse momentum of the charged lepton. We find F{sub 0} = 0.74{sub -0.34}{sup +0.22}, and F{sub +} < 0.27 at the 95% confidence level. These measurements are in agreement with the standard model predictions.

  20. Precision measurement of the top-quark mass in lepton+jets final states

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich

    2014-07-17

    We measure the mass of the top quark in leptonmore » $+$jets final states using the full sample of $$p\\bar{p}$$ collision data collected by the D0 experiment in Run II of the Fermilab Tevatron Collider at $$\\sqrt s=1.96 $$TeV, corresponding to $$9.7 {\\rm fb}^{-1}$$ of integrated luminosity. We use a matrix element technique that calculates the probabilities for each event to result from $$t\\bar t$$ production or background. The overall jet energy scale is constrained in situ by the mass of the $W$ boson. We measure $$m_t=174.98\\pm0.76$$ GeV. In conclusion, this constitutes the most precise single measurement of the top-quark mass.« less

  1. Measurement of the Top Quark Mass in the All-Hadronic Mode at CDF

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Arisawa, T.; Artikov, A.; /Dubna, JINR /Texas A-M

    2011-12-01

    A measurement of the top quark mass (M{sub top}) in the all-hadronic decay channel is presented. It uses 5.8 fb{sup -1} of p{bar p} data collected with the CDF II detector at the Fermilab Tevatron Collider. Events with six to eight jets are selected by a neural network algorithm and by the requirement that at least one of the jets is tagged as a b quark jet. The measurement is performed with a likelihood fit technique, which simultaneously determines M{sub top} and the jet energy scale (JES) calibration. The fit yields a value of M{sub top} = 172.5 {+-} 1.4 (stat) {+-} 1.0 (JES) {+-} 1.1 (syst) GeV/c{sup 2}.

  2. Precision measurement of the top-quark mass in lepton$+$jets final states

    SciTech Connect (OSTI)

    Abazov, Victor Mukhamedovich

    2015-06-04

    We measure the mass of the top quark in lepton þ jets final states using the full sample of pp¯ collision data collected by the D0 experiment in Run II of the Fermilab Tevatron Collider at √s = 1.96 TeV, corresponding to 9.7 fb-1 of integrated luminosity. We also use a matrix element technique that calculates the probabilities for each event to result from tt¯ production or background. Furthermore, the overall jet energy scale is constrained in situ by the mass of the W boson. We measure mt = 174.98 ± 0.76 GeV. As a result, this constitutes the most precise single measurement of the top-quark mass.

  3. Precise measurement of the top quark mass in dilepton decays using optimized neutrino weighting

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich

    2015-11-11

    We measure the top quark mass in dilepton final states of tt¯ events in pp¯ collisions at √s= 1.96 TeV, using data corresponding to an integrated luminosity of 9.7 fb-1 at the Fermilab Tevatron Collider. The analysis features a comprehensive optimization of the neutrino weighting method to minimize the statistical uncertainties. Furthermore, we improve the calibration of jet energies using the calibration determined in tt¯ → lepton + jets events, which reduces the otherwise limiting systematic uncertainty from the jet energy scale. As a result, the measured top quark mass is mt = 173.32±1.36(stat)±0.85(syst) GeV.

  4. Anti pp searches for quark-gluon plasma at TeV I

    SciTech Connect (OSTI)

    Turkot, F.

    1986-06-01

    Three experiments that have been approved to run at TeV I are discussed from the viewpoint of their capability to search for evidence of the QCD phase transition in proton-antiproton collisions at 1.6 TeV. One of these experiments, E-735, was proposed as a dedicated search for quark-gluon plasma effects with a detector designed to study large total E/sub T/, low P/sub T/ individual particles. The other two, E-741 (CDF) and E-740 (DO), embody general purpose four-pi detectors designed primarily to study the physics of W and Z bosons and other large P/sub T/ phenomena. The detectors and their quark-gluon plasma signals are compared. 8 refs., 6 figs., 4 tabs. (LEW)

  5. Classical strongly coupled quark-gluon plasma. III. The free energy

    SciTech Connect (OSTI)

    Cho, Sungtae; Zahed, Ismail

    2009-04-15

    We explore further the classical quark-gluon plasma using methods from classical liquids. The partition function of an ensemble of SU(N{sub c}) colored charge spheres is constructed. We analyze it using a cumulant expansion (low density) and a loop expansion (high temperature) after resumming the Debye screening effects. The pertinent free energies are derived in both limits and compared with recent molecular dynamics results.

  6. Event-by-event hydrodynamics: A better tool to study the Quark-Gluon plasma

    SciTech Connect (OSTI)

    Grassi, Frederique

    2013-03-25

    Hydrodynamics has been established as a good tool to describe many data from relativistic heavyion collisions performed at RHIC and LHC. More recently, it has become clear that it is necessary to use event-by-event hydrodynamics (i.e. describe each collision individually using hydrodynamics), an approach first developed in Brazil. In this paper, I review which data require the use of event-by-event hydrodynamics and what more we may learn on the Quark-Gluon Plasma with this.

  7. A mean field theory for the cold quark gluon plasma applied to stellar structure

    SciTech Connect (OSTI)

    Fogaca, D. A.; Navarra, F. S.; Franzon, B.; Horvath, J. E.

    2013-03-25

    An equation of state based on a mean-field approximation of QCD is used to describe the cold quark gluon plasma and also to study the structure of compact stars. We obtain stellar masses compatible with the pulsar PSR J1614-2230 that was determined to have a mass of (1.97 {+-} 0.04 M{sub Circled-Dot-Operator }), and the corresponding radius around 10-11 km.

  8. Structure of the ground state of a nonsuperfluid dense quark-gluon plasma

    SciTech Connect (OSTI)

    Khodel, V. A. Zverev, M. V. Pankratov, S. S.; Clark, J. W.

    2009-08-15

    The single-particle spectrum and momentum distribution of quasiparticles in a cold dense quark-gluon plasma are calculated within the Fermi liquid approach. It is shown that this system does not behave as a standard Fermi liquid: at zero temperature, the single-particle spectrum has a plateau at the Fermi surface, while the Fermi surface itself has a nonzero volume in momentum space.

  9. Probing the Properties of the Strongly-Interacting Quark Gluon Plasma at RHIC

    SciTech Connect (OSTI)

    Jia, J.

    2010-03-01

    Experimental evidences at RHIC, for a strongly-interacting quark gluon plasma (sQGP), are reviewed. We discuss three related phenomena, elliptic flow, jet quenching and medium responses, that have provided much of the evidences. We examine current constraints on the transport properties of sQGP from these phenomena, point out their intrinsic connections and uncertainties, and outline future improvements on the study of the sQGP, particularly those using heavy flavor probes.

  10. Rare top quark decays in Alternative Left-Right Symmetric Models

    SciTech Connect (OSTI)

    Gaitan, R.; Miranda, O. G.; Cabral-Rosetti, L. G.

    2007-06-19

    We evaluate the flavor changing neutral currents (FCNC) decay t {yields} H0 + c in the context of Alternative Left-Right symmetric Models (ALRM) with extra isosinglet heavy fermions; the FCNC decays may place at tree level and are only supressed by the mixing between ordinary top and charm quarks. We also comment on the decay process t {yields} c + {gamma}, which involves radiative corrections.

  11. MEASUREMENT OF THE STRANGE QUARK CONTRIBUTION TO THE VECTOR STRUCTURE OF THE PROTON

    SciTech Connect (OSTI)

    Sarah Phillips

    2007-11-30

    The goal of the G0 experiment is to determine the contribution of the strange quarks in the quark-antiquark sea to the structure of the nucleon. To this end, the experiment measured parityviolating asymmetries from elastic electron-proton scattering from 0.12 ≤ Q2 ≤ 1.0 (GeV/c)2 at Thomas Jefferson National Accelerator Facility. These asymmetries come from the interference of the electromagnetic and neutral weak interactions, and are sensitive to the strange quark contributions in the proton. The results from the forward-angle measurement, the linear combination of the strange electric and magnetic form factors GsE +ηGsM, suggest possible non-zero, Q2 dependent, strange quark contributions and provide new information to understand the magnitude of the contributions. This dissertation presents the analysis and results of the forward-angle measurement. In addition, the G0 experiment measured the beam-normal single-spin asymmetry in the elastic scattering of transversely polarized 3 GeV electrons from unpolarized protons at Q2 = 0.15, 0.25 (GeV/c)2 as part of the forward-angle measurement. The transverse asymmetry provides a direct probe of the imaginary component of the two-photon exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments. The results of the measurement indicate that calculations using solely the elastic nucleon intermediate state are insufficient and generally agree with calculations that include significant inelastic hadronic intermediate state contributions. This dissertation presents the analysis and results of this measurement.

  12. Deconfinement to quark matter in neutron stars - The influence of strong magnetic fields

    SciTech Connect (OSTI)

    Dexheimer, V.; Negreiros, R.; Schramm, S.; Hempel, M.

    2013-03-25

    We use an extended version of the hadronic SU(3) non-linear realization of the sigma model that also includes quarks to study hybrid stars. Within this approach, the degrees of freedom change naturally as the temperature/density increases. Different prescriptions of charge neutrality, local and global, are tested and the influence of strong magnetic fields and the anomalous magnetic moment on the particle population is discussed.

  13. A review of the intrinsic heavy quark content of the nucleon

    SciTech Connect (OSTI)

    Brodsky, S. J.; Kusina, A.; Lyonnet, F.; Schienbein, I.; Spiesberger, H.; Vogt, R.

    2015-04-29

    We present a review of the state of the art of our understanding of the intrinsic charm and bottom content of the nucleon. We discuss theoretical calculations, constraints from global analyses, and collider observables sensitive to the intrinsic heavy quark distributions. In addition, a particular emphasis is put on the potential of a high energy and high luminosity fixed target experiment using the LHC beams (AFTER@LHC) to search for intrinsic charm.

  14. A Review of the Intrinsic Heavy Quark Content of the Nucleon

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Brodsky, S. J.; Kusina, A.; Lyonnet, F.; Schienbein, I.; Spiesberger, H.; Vogt, R.

    2015-01-01

    We present a review of the state of the art of our understanding of the intrinsic charm and bottom content of the nucleon. We discuss theoretical calculations, constraints from global analyses, and collider observables sensitive to the intrinsic heavy quark distributions. A particular emphasis is put on the potential of a high energy and high luminosity fixed target experiment using the LHC beams (AFTER@LHC) to search for intrinsic charm.

  15. Leon Lederman, the K-meson, the Muon Neutrino, and the Bottom Quark

    Office of Scientific and Technical Information (OSTI)

    Leon Lederman, the K-meson, the Muon Neutrino, and the Bottom Quark His Honors * His Involvement in Science Education His Wisdom and Humor * Resources with Additional Information Leon Lederman started his career in Physics at Columbia University, where he earned his Ph.D. in 1952. He 'stayed on at Columbia following his studies, remaining for nearly 30 years, as the Eugene Higgins Professor and, from 1961 until 1979, as director of Nevis Laboratories in Irvington, the Columbia physics department

  16. Search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks using a matrix element method

    SciTech Connect (OSTI)

    Khachatryan, V.

    2015-06-09

    A search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks is presented. Events with hadronic jets and one or two oppositely charged leptons are selected from a data sample corresponding to an integrated luminosity of 19.5fb-1 collected by the CMS experiment at the LHC in pp collisions at a centre-of-mass energy of 8TeV. In order to separate the signal from the larger tt + jets background, this analysis uses a matrix element method that assigns a probability density value to each reconstructed event under signal or background hypotheses. The ratio between the two values is used in a maximum likelihood fit to extract the signal yield. The results are presented in terms of the measured signal strength modifier, ?, relative to the standard model prediction for a Higgs boson mass of 125GeV. The observed (expected) exclusion limit at a 95 % confidence level is ?<4.2 (3.3), corresponding to a best fit value ?^=1.2+1.6-1.5.

  17. Search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks using a matrix element method

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2015-06-09

    A search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks is presented. Events with hadronic jets and one or two oppositely charged leptons are selected from a data sample corresponding to an integrated luminosity of 19.5fb-1 collected by the CMS experiment at the LHC in pp collisions at a centre-of-mass energy of 8TeV. In order to separate the signal from the larger tt¯ + jets background, this analysis uses a matrix element method that assigns a probability density value to each reconstructed event under signal or background hypotheses. The ratiomore » between the two values is used in a maximum likelihood fit to extract the signal yield. The results are presented in terms of the measured signal strength modifier, μ, relative to the standard model prediction for a Higgs boson mass of 125GeV. The observed (expected) exclusion limit at a 95 % confidence level is μ < 4.2 (3.3), corresponding to a best fit value μ^ = 1.2+1.6-1.5.« less

  18. Search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks using a matrix element method

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, V.

    2015-06-09

    A search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks is presented. Events with hadronic jets and one or two oppositely charged leptons are selected from a data sample corresponding to an integrated luminosity of 19.5fb-1 collected by the CMS experiment at the LHC in pp collisions at a centre-of-mass energy of 8TeV. In order to separate the signal from the larger tt + jets background, this analysis uses a matrix element method that assigns a probability density value to each reconstructed event under signal or background hypotheses. The ratiomorebetween the two values is used in a maximum likelihood fit to extract the signal yield. The results are presented in terms of the measured signal strength modifier, ?, relative to the standard model prediction for a Higgs boson mass of 125GeV. The observed (expected) exclusion limit at a 95 % confidence level is ?+1.6-1.5.less

  19. Effect of quark sector minimal flavor violation on neutrinoless double beta decay

    SciTech Connect (OSTI)

    Dudley, Brian; Kolda, Christopher [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2009-01-01

    The question of whether neutrino masses are Dirac or Majorana is one of the most important, and most difficult, questions remaining in the neutrino sector. Searches for neutrinoless double {beta} decay may help to resolve this question, but are also sensitive to new, higher-dimension {delta}L=2 operators. In this paper we place two phenomenological constraints on these operators at dimension d{<=}11. First, we require that the operators obey the quark flavor symmetries of the standard model, with any violation of the symmetries being due to Yukawa interactions, a scheme known as minimal flavor violation. Second, we require that the operators which generate neutrinoless double {beta} decay, and any operators related by the flavor symmetries, do not induce neutrino masses above the experimental and astrophysical limits. We find that these requirements severely constrain the operators which can violate lepton number, such that most can no longer contribute to neutrinoless double {beta} decay at observable rates. It is noteworthy that quark flavor symmetries can play such a strong role in constraining new leptonic physics, even when that physics is not quark flavor changing. Those few operators that can mimic a Majorana neutrino mass then appear with cutoffs below a TeV, and represent new physics which could be directly probed at the LHC or a future linear collider.

  20. Exclusion of an Exotic Top Quark with -4/3 Electric Charge Using Soft Lepton Tagging

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.; Apresyan, A.; /Purdue U. /Waseda U.

    2010-06-01

    We present a measurement of the electric charge of the top quark using p{bar p} collisions corresponding to an integrated luminosity of 2.7 fb{sup -1} at the CDF II detector. We reconstruct t{bar t} events in the lepton+jets final state and use kinematic information to determine which b-jet is associated with the leptonically- or hadronically-decaying t-quark. Soft lepton taggers are used to determine the b-jet flavor. Along with the charge of the W boson decay lepton, this information permits the reconstruction of the top quark's electric charge. Out of 45 reconstructed events with 2.4 {+-} 0.8 expected background events, 29 are reconstructed as tt with the standard model +2/3 charge, whereas 16 are reconstructed as t{bar t} with an exotic -4/3 charge. This is consistent with the standard model and excludes the exotic scenario at 95% confidence level. This is the strongest exclusion of the exotic charge scenario and the first to use soft leptons for this purpose.

  1. Extraction of quark transversity distribution and Collins fragmentation functions with QCD evolution

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kang, Zhong-Bo; Prokudin, Alexei; Sun, Peng; Yuan, Feng

    2016-01-13

    In this paper, we study the transverse momentum dependent (TMD) evolution of the Collins azimuthal asymmetries in e+e- annihilations and semi-inclusive hadron production in deep inelastic scattering (SIDIS) processes. All the relevant coefficients are calculated up to the next-to-leading logarithmic (NLL) order accuracy. By applying the TMD evolution at the approximate NLL order in the Collins- Soper-Sterman (CSS) formalism, we extract transversity distributions for u and d quarks and Collins fragmentation functions from current experimental data by a global analysis of the Collins asymmetries in back-to-back di-hadron productions in e+e- annihilations measured by BELLE and BABAR Collaborations and SIDIS datamore » from HERMES, COMPASS, and JLab HALL A experiments. The impact of the evolution effects and the relevant theoretical uncertainties are discussed. We further discuss the TMD interpretation for our results, and illustrate the unpolarized quark distribution, transversity distribution, unpolarized quark fragmentation and Collins fragmentation functions depending on the transverse momentum and the hard momentum scale. Finally, we give predictions and discuss impact of future experiments.« less

  2. Search for Pair Production of Supersymmetric Top Quarks in Dilepton Events at the Tevatron

    SciTech Connect (OSTI)

    Johnson, William Casey; /UC, Davis

    2010-05-01

    We search for pair production of the supersymmetric partner of the top quark, the stop quark {tilde t}{sub 1}, decaying to a b-quark and a chargino {tilde {chi}}{sub 1}{sup {+-}} with a subsequent decay into a neutralino {tilde {chi}}{sub 1}{sup 0}, lepton {ell}, and neutrino {nu}. Using 2.7 fb{sup -1} of {radical}s = 1.96 TeV p{bar p} collision data collected by the CDF II experiment, we reconstruct the mass of candidate stop events and fit the observed mass spectrum to a combination of standard model processes and stop signal. No evidence of {tilde t}{sub 1}{tilde {bar 1}}{sub 1} production is found, therefore we set 95% C.L. limits on the masses of the stop and the neutralino for several values of the chargino mass and the branching ratio {Beta} ({tilde {chi}}{sub 1}{sup {+-}} {yields} {tilde {chi}}{sub 1}{sup 0}{ell}{sup {+-}}{nu}).

  3. Search for Higgs Bosons Produced in Association with b-Quarks

    SciTech Connect (OSTI)

    Aaltonen, T

    2012-02-22

    We present a search for neutral Higgs bosons ? decaying into bb?, produced in association with b quarks in ppb? collisions. This process could be observable in supersymmetric models with high values of tan ?. The event sample corresponds to 2.6 fb-1 of integrated luminosity collected with the CDF II detector at the Fermilab Tevatron collider. We search for an enhancement in the mass of the two leading jets in events with three jets identified as coming from b quarks using a displaced vertex algorithm. A data-driven procedure is used to estimate the dijet mass spectrum of the nonresonant multijet background. The contributions of backgrounds and a possible Higgs boson signal are determined by a two-dimensional fit of the data, using the dijet mass together with an additional variable which is sensitive to the flavor composition of the three tagged jets. We set mass-dependent limits on ?(ppb? = ?b) x ?(?= bb?) which are applicable for a narrow scalar particle ? produced in association with b quarks. We also set limits on tan ? in supersymmetric Higgs models including the effects of the Higgs boson width.

  4. Search for Higgs Bosons Produced in Association with b-Quarks

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T

    2012-02-22

    We present a search for neutral Higgs bosons φ decaying into bb¯, produced in association with b quarks in ppb¯ collisions. This process could be observable in supersymmetric models with high values of tan β. The event sample corresponds to 2.6 fb-1 of integrated luminosity collected with the CDF II detector at the Fermilab Tevatron collider. We search for an enhancement in the mass of the two leading jets in events with three jets identified as coming from b quarks using a displaced vertex algorithm. A data-driven procedure is used to estimate the dijet mass spectrum of the nonresonant multijetmore » background. The contributions of backgrounds and a possible Higgs boson signal are determined by a two-dimensional fit of the data, using the dijet mass together with an additional variable which is sensitive to the flavor composition of the three tagged jets. We set mass-dependent limits on σ(ppb¯ = φb) x Β(φ= bb¯) which are applicable for a narrow scalar particle φ produced in association with b quarks. We also set limits on tan β in supersymmetric Higgs models including the effects of the Higgs boson width.« less

  5. Meson properties at finite temperature in a three flavor nonlocal chiral quark model with Polyakov loop

    SciTech Connect (OSTI)

    Contrera, G. A.; Dumm, D. Gomez; Scoccola, Norberto N.

    2010-03-01

    We study the finite temperature behavior of light scalar and pseudoscalar meson properties in the context of a three-flavor nonlocal chiral quark model. The model includes mixing with active strangeness degrees of freedom, and takes care of the effect of gauge interactions by coupling the quarks with the Polyakov loop. We analyze the chiral restoration and deconfinement transitions, as well as the temperature dependence of meson masses, mixing angles and decay constants. The critical temperature is found to be T{sub c{approx_equal}}202 MeV, in better agreement with lattice results than the value recently obtained in the local SU(3) PNJL model. It is seen that above T{sub c} pseudoscalar meson masses get increased, becoming degenerate with the masses of their chiral partners. The temperatures at which this matching occurs depend on the strange quark composition of the corresponding mesons. The topological susceptibility shows a sharp decrease after the chiral transition, signalling the vanishing of the U(1){sub A} anomaly for large temperatures.

  6. Search for a heavy particle decaying to a top quark and a light quark in $p\\bar{p}$ collisions at $\\sqrt{s}=1.96$ TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2012-03-01

    We present a search for a new heavy particle M produced in association with a top quark, p{bar p} {yields} t(M {yields} {bar t}q) or p{bar p} {yields} {bar t}({bar M} {yields} t{bar q}), where q stands for up quarks and down quarks. Such a particle may explain the recent anomalous measurements of top-quark forward-backward asymmetry. If the light-flavor quark (q) is reconstructed as a jet (j), this gives a {bar t}+j or t+j resonance in t{bar t}+jet events, a previously unexplored experimental signature. In a sample of events with exactly one lepton, missing transverse momentum and at least five jets, corresponding to an integrated luminosity of 8.7 fb{sup -1} collected by the CDF II detector, we find the data to be consistent with the standard model. We set cross-section upper limits on the production (p{bar p} {yields} Mt or {bar M} {bar t}) at 95% confidence level from 0.61 pb to 0.02 pb for M masses ranging from 200 GeV/c{sup 2} to 800 GeV/c{sup 2}, respectively.

  7. Measurement of the Single Top Quark Production Cross Section in 1.96-TeV Proton-Antiproton Collisions

    SciTech Connect (OSTI)

    Nakamura, Koji; /Tsukuba U.

    2009-03-01

    Top quarks are predominantly produced in pairs via the strong interaction in {bar p}p collisions at {radical}s = 1.96 TeV . The top quark has a weak isospin 1/2, composing a weak isospin doublet with the bottom quark. This characteristic predicts not only top quark pair production via strong interaction but also single production together with a bottom quark via weak interaction. However, finding single top quark production is challenging since it is rarely produced ({sigma}{sub singletop} = 2.9 pb) against background processes with the same final state like W+jets and t{bar t}. A measurement of electroweak single top production probes the W-t-b vertex, which provides a direct determination of the Cabbibo-Kobayashi-Maskawa (CKM) matrix element |V{sub tb}|. The sample offers a source of almost 100% polarized top quarks. This thesis describes an optimized search for s-channel single top quark production and a measurement of the single top production cross section using 2.7 fb{sup -1} of data accumulated with the CDF detector. We are using events with one high-p{sub T} lepton, large missing E{sub T} and two identified b-quark jets where one jet is identified using a secondary vertex tagger, called SecVtx, and the other jet is identified using SecVtx or a jet probability tagger, called JetProb. In this analysis we have developed a kinematics fitter and a likelihood-based separator between signal and background. As a result, we found that the probability (p-value) that the candidate events originate from a background fluctuation in the absence of single top s-channel production is 0.003, which is equivalent to 2.7 {sigma} deviations in Gaussian statistics, and this excess corresponds to the single top s-channel cross section of 2.38{sub -0.84}{sup +1.01} pb. An observed value of |V{sub tb}| is 1.43{sub -0.26}{sup +0.38}(experimental) {+-} 0.11(theory). We also set the 95% CL. upper limit of {sigma}{sub s} = 4.15 pb for the s-channel production cross section.

  8. Gluons and the Quark Sea at High Energies: Distributions, Polarization, Tomography

    SciTech Connect (OSTI)

    Boer, Daniel; Diehl, Markus; Milner, Richard; Venugopalan, Raju; Vogelsang, Werner; Kaplan, David; Montgomery, Hugh; Vigdor, Steven; Accardi, A.; Aschenauer, E.C.; Burkardt, M.; Ent, R.; Guzey, V.; Hasch, D.; Kumar, K.; Lamont, M.A.C.; Li, Ying-chuan; Marciano, W.; Marquet, C.; Sabatie, F.; Stratmann, M.; /more authors..

    2012-06-07

    This report on the science case for an Electron-Ion Collider (EIC) is the result of a ten-week program at the Institute for Nuclear Theory (INT) in Seattle (from September 13-November 19, 2010), motivated by the need to develop a strong case for the continued study of the QCD description of hadron structure in the coming decades. Hadron structure in the valence quark region will be studied extensively with the Jefferson Lab 12 GeV science program, the subject of an INT program the previous year. The focus of the INT program was on understanding the role of gluons and sea quarks, the important dynamical degrees of freedom describing hadron structure at high energies. Experimentally, the most direct and precise way to access the dynamical structure of hadrons and nuclei at high energies is with a high luminosity lepton probe in collider mode. An EIC with optimized detectors offers enormous potential as the next generation accelerator to address many of the most important, open questions about the fundamental structure of matter. The goal of the INT program, as captured in the writeups in this report, was to articulate these questions and to identify golden experiments that have the greatest potential to provide definitive answers to these questions. At resolution scales where quarks and gluons become manifest as degrees of freedom, the structure of the nucleon and of nuclei is intimately connected with unique features of QCD dynamics, such as confinement and the self-coupling of gluons. Information on hadron sub-structure in DIS is obtained in the form of 'snapshots' by the 'lepton microscope' of the dynamical many-body hadron system, over different momentum resolutions and energy scales. These femtoscopic snapshots, at the simplest level, provide distribution functions which are extracted over the largest accessible kinematic range to assemble fundamental dynamical insight into hadron and nuclear sub-structure. For the proton, the EIC would be the brightest femtoscope scale lepton-collider ever, exceeding the intensity of the HERA collider a thousand fold. HERA, with its center-of-mass (CM) energy of 320 GeV, was built to search for quark substructure. An EIC, with its scientific focus on studying QCD in the regime where the sea quarks and gluons dominate, would have a lower CM energy. In a staged EIC design, the CM energy will range from 50-70 GeV in stage I to approximately twice that for the full design. In addition to being the first lepton collider exploring the structure of polarized protons, an EIC will also be the first electron-nucleus collider, probing the gluon and sea quark structure of nuclei for the first time. Following the same structure as the scientific discussions at the INT, this report is organized around the following four major themes: (1) The spin and flavor structure of the proton; (2) Three dimensional structure of nucleons and nuclei in momentum and configuration space; (3) QCD matter in nuclei; and (4) Electroweak physics and the search for physics beyond the Standard Model. In this executive summary, we will briefly outline the outstanding physics questions in these areas and the suite of measurements that are available with an EIC to address these. The status of accelerator and detector designs is addressed at the end of the summary. Tables of golden measurements for each of the key science areas outlined are presented on page 12. In addition, each chapter in the report contains a comprehensive overview of the science topic addressed. Interested readers are encouraged to read these and the individual contributions for more details on the present status of EIC science.

  9. New method for the experimental study of topological effects in the quark-gluon plasma

    SciTech Connect (OSTI)

    Ajitanand, N. N.; Lacey, Roy A.; Taranenko, A.; Alexander, J. M.

    2011-01-15

    A new method is presented for the quantitative measurement of charge separation about the reaction plane. A correlation function is obtained whose shape is concave when there is a net separation of positive and negative charges. Correlations not specifically associated with charge, from flow, jets, and momentum conservation, do not influence the shape or magnitude of the correlation function. Detailed simulations are used to demonstrate the effectiveness of the method for the quantitative measurement of charge separation. Such measurements are a prerequisite to the investigation of topological charge effects in the quark-gluon plasma as derived from the 'strong CP problem'.

  10. Ground state heavy baryon production in a relativistic quark-diquark model

    SciTech Connect (OSTI)

    Gomshi Nobary, M. A.; Sepahvand, R.

    2007-12-01

    We use current-current interaction to calculate the fragmentation functions to describe the production of spin-1/2, spin-1/2{sup '}, and spin-3/2 baryons with massive constituents in a relativistic quark-diquark model. Our results are in their analytic forms and are applicable for singly, doubly, and triply heavy baryons. We discuss the production of {omega}{sub bbc}, {omega}{sub bcc}, and {omega}{sub ccc} baryons in some detail. The results are satisfactorily compared with those obtained for triply heavy baryons calculated in a perturbative regime within reasonable values of the parameters involved.

  11. RHIC PHYSICS: THE QUARK GLUON PLASMA AND THE COLOR GLASS CONDENSATE: 4 LECTURES

    SciTech Connect (OSTI)

    MCLERRAN,L.

    2003-01-01

    The purpose of these lectures is to provide an introduction to the physics issues which are being studied in the RHIC heavy ion program. These center around the production of new states of matter. The Quark Gluon Plasma is thermal matter which once existed in the big bang which may be made at RHIC. The Color Glass Condensate is a universal form of matter which controls the high energy limit of strong interactions. Both such forms of matter might be produced and probed at RHIC.

  12. A relativistic quark model with infrared confinement and the tetraquark state

    SciTech Connect (OSTI)

    Dubnicka, S.; Dubnickova, A. Z.; Ivanov, M. A.; Koerner, J. G.; Saidullaeva, G. G.

    2011-05-23

    We explore the consequences of treating the X(3872) meson as a tetraquark bound state. As dynamical framework we employ a relativistic constituent quark model which includes infrared confinement in an effective way. We calculate the decay widths of the observed channels X{yields}J/{psi}+2{pi}(3{pi}) and X{yields}D-bar{sup 0}+D{sup 0}+{pi}{sup 0} via the intermediate off-shell states X{yields}J/{psi}+{rho}({omega}) and X{yields}D-bar+D*. For reasonable values of the size parameter {Lambda}{sub X} of the X(3872) we find consistency with the available experimental data.

  13. Collider Detector at Fermilab (CDF): Data from the Top Group's Top Quark Research

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    The Collider Detector at Fermilab (CDF) is a Tevatron experiment at Fermilab. The Tevatron, a powerful particle accelerator, accelerates protons and antiprotons close to the speed of light, and then makes them collide head-on inside the CDF detector. The CDF detector is used to study the products of such collisions. The CDF Physics Group at Fermilab is organized into six working groups, each with a specific focus. The Top group studies the properties of the top quark, the heaviest known fundamental particle. Their public web page makes data and numerous figures available from both CDF Runs I and II.

  14. DZero (D0) Experiment Results for Top Quark Physics from the Fermilab Tevatron

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    The D0 (DZero) Experiment is a worldwide collaboration of scientists conducting research on the fundamental nature of matter. The experiment is located at the Tevatron Collider, Fermilab. The research is focused on precise studies of interactions of protons and antiprotons and involves an intense search for subatomic clues that reveal the character of the building blocks of the universe. This web page provides access to Run II research results of the Top Quark Physics group, including preliminary, submitted, and published results. Figures and data plots are found in the directories with their respective papers.

  15. Search for Quark Compositeness with the Dijet Centrality Ratio in $pp$ Collisions at $\\sqrt{s}=7$ TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan; et al.

    2010-12-01

    A search for quark compositeness in the form of quark contact interactions, based on hadronic jet pairs (dijets) produced in proton-proton collisions at sqrt(s)=7 TeV, is described. The data sample of the study corresponds to an integrated luminosity of 2.9 inverse picobarns collected with the CMS detector at the LHC. The dijet centrality ratio, which quantifies the angular distribution of the dijets, is measured as a function of the invariant mass of the dijet system and is found to agree with the predictions of the Standard Model. A statistical analysis of the data provides a lower limit on the energy scale of quark contact interactions. The sensitivity of the analysis is such that the expected limit is 2.9 TeV; because the observed value of the centrality ratio at high invariant mass is below the expectation, the observed limit is 4.0 TeV at the 95% confidence level.

  16. Search for Single Vectorlike Quarks in pp̄ Collisions at √s=1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G. A.; et al

    2011-02-22

    We present a search for hypothetical vectorlike quarks in pp̄ collisions at √s=1.96 TeV. The data were collected by the D0 detector at the Fermilab Tevatron Collider and correspond to an integrated luminosity of 5.4 fb⁻¹. We select events with a final state composed of a W or Z boson and a jet consistent with a heavy object decay. We observe no significant excess in comparison to the background prediction and set limits on production cross sections for vectorlike quarks decaying to W+jet and Z+jet. These are the most stringent limits to date for electroweak single vectorlike quark production atmore » hadron colliders.« less

  17. One-loop gluon amplitude for heavy-quark production at next-to-next-to-leading order

    SciTech Connect (OSTI)

    Anastasiou, Charalampos; Aybat, S. Mert

    2008-12-01

    We compute the one-loop QCD amplitude for the process gg{yields}QQ in dimensional regularization through order {epsilon}{sup 2} in the dimensional regulator and for arbitrary quark mass values. This result is an ingredient of the next-to-next-to-leading order cross section for heavy-quark production at hadron colliders. The calculation is performed in conventional dimensional regularization using well-known reduction techniques as well as a method based on recent ideas for the functional form of one-loop integrands in four dimensions.

  18. Study of the all orders multiplicative renormalizability of a local confining quark action in the Landau gauge

    SciTech Connect (OSTI)

    Capri, M.A.L. Fiorentini, D. Sorella, S.P.

    2015-05-15

    The inverse of the Faddeev–Popov operator plays a pivotal role within the Gribov–Zwanziger approach to the quantization of Euclidean Yang–Mills theories in Landau gauge. Following a recent proposal (Capri et al., 2014), we show that the inverse of the Faddeev–Popov operator can be consistently coupled to quark fields. Such a coupling gives rise to a local action while reproducing the behaviour of the quark propagator observed in lattice numerical simulations in the non-perturbative infrared region. By using the algebraic renormalization framework, we prove that the aforementioned local action is multiplicatively renormalizable to all orders.

  19. One-loop matching of {delta}S=2 four-quark operators with improved staggered fermions

    SciTech Connect (OSTI)

    Becher, Thomas; Gamiz, Elvira; Melnikov, Kirill

    2005-10-01

    We compute O({alpha}{sub s}) lattice-to-continuum perturbative matching coefficients for the {delta}S=2 flavor changing four-quark operators for the Asqtad improved staggered action. In conjunction with lattice simulations with three flavors of light, dynamical quarks, our results yield an unquenched determination of B{sub K}, the parameter that determines the amount of indirect CP violation in the neutral kaon system. Its value is an important input for the unitarity triangle analysis of weak decays.

  20. Thermal charm production in a quark-gluon plasma in Pb-Pb collisions at {radical}(s{sub NN})=5.5 TeV

    SciTech Connect (OSTI)

    Zhang Benwei; Ko Cheming; Liu Wei

    2008-02-15

    Charm production from the quark-gluon plasma created in the midrapidity of central heavy ion collisions at the Large Hadron Collider (LHC) is studied in the next-to-leading order in QCD. Using a schematic longitudinally boost-invariant and transversally expanding fire-cylinder model, we find that charm production could be appreciably enhanced at LHC as a result of the high temperature that is expected to be reached in the produced quark-gluon plasma. Sensitivities of our results to the number of charm quark pairs produced from initial hard scattering, the initial thermalization time and temperature of the quark-gluon plasma, and the charm quark mass are also studied.

  1. Search for Scalar Top Quark Production in $p\\bar{p}$ Collisions at $\\sqrt{s}=1.96$ TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Arisawa, T.; Artikov, A.; /Dubna, JINR /Texas A-M

    2012-03-01

    We report on a search for the supersymmetric partner of the top quark (scalar top) decaying into a charm quark and a neutralino in p{bar p} collisions at {radical}s = 1.96 TeV. The data sample, collected by the CDF II detector at the Fermilab Tevatron, corresponds to an integrated luminosity of 2.6 fb{sup -1}. Candidate events are selected by requiring two or more jets and a large imbalance in the transverse momentum. To enhance the analysis sensitivity, at least one of the jets is required to be identified as originating from a charm quark using an algorithm specifically designed for this analysis. The selected events are in good agreement with standard model predictions. In the case of large mass splitting between the scalar top quark and the neutralino we exclude a scalar top quark mass below 180 GeV/c{sup 2} at 95% confidence level.

  2. Gauge bosons and heavy quarks: Proceedings of Summer Institute on Particle Physics

    SciTech Connect (OSTI)

    Hawthorne, J.F.

    1991-01-01

    This report contains papers on the following topics: Z decays and tests of the standard model; future possibilities for LEP; studies of the interactions of electroweak gauge bosons; top quark topics; the next linear collider; electroweak processes in hadron colliders; theoretical topics in B-physics; experimental aspects of B-physics; B-factory storage ring design; rare kaon decays; CP violation in K{sup 0} decays at CERN; recent K{sup 0} decay results from Fermilab E-731; results from LEP on heavy quark physics; review of recent results on heavy flavor production; weak matrix elements and the determination of the weak mixing angles; recent results from CLEO I and a glance at CLEO II data; recent results from ARGUS; neutrino lepton physics with the CHARM 2 detector; recent results from the three TRISTAN experiments; baryon number violation at high energy in the standard model: fact or fiction New particle searches at LEP; review of QCD at LEP; electroweak interactions at LEP; recent results on W physics from the UA2 experiment at the CERN {rho}{bar {rho}} collider; B physics at CDF; and review of particle astrophysics.

  3. Search for neutral MSSM Higgs bosons decaying into a pair of bottom quarks

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-11-11

    A search for neutral Higgs bosons decaying into a bb¯ quark pair and produced in association with at least one additional b quark is presented. This signature is sensitive to the Higgs sector of the minimal supersymmetric standard model (MSSM) with large values of the parameter tan β. The analysis is based on data from proton-proton collisions at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.7 fb–1. The results are combined with a previous analysis based on 7 TeV data. No signal is observed. Stringent upper limits on the cross section times branching fraction are derived for Higgs bosons with masses up to 900 GeV, and the results are interpreted within different MSSM benchmark scenarios, mhmax, mhmod+, mhmod–, light-stau and light-stop. Observed 95% confidence level upper limits on tan β, ranging from 14 to 50, are obtained in the mhmod+ benchmark scenario.

  4. Top quark mass measurement from dilepton events at CDF II with the matrix-element method

    SciTech Connect (OSTI)

    Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G.; Ambrose, D.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; /Taiwan, Inst. Phys. /Argonne /Barcelona, IFAE /Baylor U. /INFN, Bologna /Bologna U. /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara

    2006-05-01

    We describe a measurement of the top quark mass using events with two charged leptons collected by the CDF II detector from p{bar p} collisions with {radical}s = 1.96 TeV at the Fermilab Tevatron. The likelihood in top mass is calculated for each event by convoluting the leading order matrix element describing q{bar q} {yields} t{bar t} {yields} b{ell}{nu}{sub {ell}}{bar b}{ell}{prime} {nu}{sub {ell}}, with detector resolution functions. The presence of background events in the data sample is modeled using similar calculations involving the matrix elements for major background processes. In a data sample with integrated luminosity of 340 pb{sup -1}, we observe 33 candidate events and measure M{sub top} = 165.2 {+-} 6.1(stat.) {+-} 3.4(syst.) GeV/c{sup 2}. This measurement represents the first application of this method to events with two charged leptons and is the most precise single measurement of the top quark mass in this channel.

  5. Searching for New Physics with Top Quarks and Upgrade to the Muon Spectrometer at ATLAS

    SciTech Connect (OSTI)

    Schwarz, Thomas Andrew

    2015-06-29

    Over the funding period of this award, my research has focused on searching for new physics with top quarks and in the Higgs sector. The highly energetic top quark events at the LHC are an excellent venue to search for new physics, as well as make standard model measurements. Further, the recent discovery of the Higgs boson motivates searching for new physics that could be associated with it. This one-year award has facilitated the beginning of my research program, which has resulted in four publications, several conference talks, and multiple leadership positions within physics groups. Additionally, we are contributing to ATLAS upgrades and operations. As part of the Phase I upgrade, I have taken on the responsibility of the design, prototyping, and quality control of a signal packet router for the trigger electronics of the New Small Wheel. This is a critical component of the upgrade, as the router is the main switchboard for all trigger signals to track finding processors. I am also leading the Phase II upgrade of the readout electronics of the muon spectrometer, and have been selected as the USATLAS Level-2 manager of the Phase II upgrade of the muon spectrometer. The award has been critical in these contributions to the experiment.

  6. Search for resonances decaying to top and bottom quarks with the CDF experiment

    SciTech Connect (OSTI)

    Aaltonen, Timo Antero

    2015-08-03

    We report on a search for charged massive resonances decaying to top (t) and bottom (b) quarks in the full data set of proton-antiproton collisions at a center-of-mass energy of √s = 1.96 TeV collected by the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.5 fb–1. No significant excess above the standard model background prediction is observed. We set 95% Bayesian credibility mass-dependent upper limits on the heavy charged-particle production cross section times branching ratio to tb. Using a standard model extension with a W' → tb and left-right-symmetric couplings as a benchmark model, we constrain the W' mass and couplings in the 300–900 GeV/c2 range. As a result, the limits presented here are the most stringent for a charged resonance with mass in the range 300–600 GeV/c2 decaying to top and bottom quarks.

  7. Measurement of the mass difference between $t$ and $\\bar{t}$ quarks

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2011-03-01

    We present a direct measurement of the mass difference between t and {bar t} quarks using t{bar t} candidate events in the lepton+jets channel, collected with the CDF II detector at Fermilab's 1.96 TeV Tevatron p{bar p} Collider. We make an event by event estimate of the mass difference to construct templates for top quark pair signal events and background events. The resulting mass difference distribution of data is compared to templates of signals and background using a maximum likelihood fit. From a sample corresponding to an integrated luminosity of 5.6 fb{sup -1}, we measure a mass difference, {Delta}M{sub top} = M{sub t} - M{sub {bar t}} = -3.3 {+-} 1.4 (stat) {+-} 1.0 (syst) GeV/c{sup 2}, approximately two standard deviations away from the CPT hypothesis of zero mass difference. This is the most precise measurement of a mass difference between t and its {bar t} partner to date.

  8. Measurement of the B+- lifetime and top quark identification using secondary vertex b-tagging

    SciTech Connect (OSTI)

    Schwartzman, Ariel G

    2004-02-01

    This dissertation presents a preliminary measurement of the B{sup {+-}} lifetime through the full reconstruction of its decay chain, and the identification of top quark production in the electron plus jets channel using the displaced vertex b-tagging method. Its main contribution is the development, implementation and optimization of the Kalman filter algorithm for vertex reconstruction, and of the displaced vertex technique for tagging jets arising from b quark fragmentation, both of which have now become part of the standard D0 reconstruction package. These two algorithms fully exploit the new state-of-the-art tracking detectors, recently installed as part of the Run 2 D0 upgrade project. The analysis is based on data collected during Run 2a at the Fermilab Tevatron p{bar p} Hadron Collider up to April 2003, corresponding to an integrated luminosity of 60 pb{sup -1}. The measured B meson lifetime of {tau} = 1.57 {+-} 0.18 ps is in agreement with the current world average, with a competitive level of precision expected when the full data sample becomes available.

  9. HoravaLifshitz cosmology, entropic interpretation and quarkhadron phase transition

    SciTech Connect (OSTI)

    Kheyri, F. Khodadi, M. Sepangi, Hamid Reza

    2013-05-15

    Based on the assumptions of the standard model of cosmology, a phase transition associated with chiral symmetry breaking after the electroweak transition has occurred at approximately 10 ?s after the Big Bang to convert a plasma of free quarks and gluons into hadrons. We consider such a phase transition in the context of a deformed HoravaLifshitz cosmology. The Friedmann equation for the deformed HoravaLifshitz universe is obtained using the entropic interpretation of gravity, proposed by Verlinde. We investigate the effects of the parameter ? appearing in the theory on the evolution of the physical quantities relevant to a description of the early universe, namely, the energy density and temperature before, during and after the phase transition. Finally, we study the cross-over phase transition in both high and low temperature regions in view of the recent lattice QCD simulations data. -- Highlights: ? We study the problem of the quarkhadron phase transition in the early universe, in the context of HoravaLifshitz cosmology. ? We conduct this study by including the recently introduced entropic principle. ? We study the behavior of thermodynamical parameters of the theory.

  10. Search for neutral MSSM Higgs bosons decaying into a pair of bottom quarks

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2015-11-11

    A search for neutral Higgs bosons decaying into a bb¯ quark pair and produced in association with at least one additional b quark is presented. This signature is sensitive to the Higgs sector of the minimal supersymmetric standard model (MSSM) with large values of the parameter tan β. The analysis is based on data from proton-proton collisions at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.7 fb–1. The results are combined with a previous analysis based on 7 TeV data. No signal is observed. Stringent upper limitsmore » on the cross section times branching fraction are derived for Higgs bosons with masses up to 900 GeV, and the results are interpreted within different MSSM benchmark scenarios, mhmax, mhmod+, mhmod–, light-stau and light-stop. Observed 95% confidence level upper limits on tan β, ranging from 14 to 50, are obtained in the mhmod+ benchmark scenario.« less

  11. Heavy-Quark Associated Production with One Hard Photon at Hadron Colliders

    SciTech Connect (OSTI)

    Hartanto, Heribertus Bayu

    2013-01-01

    We present the calculation of heavy-quark associated production with a hard photon at hadron colliders, namely $pp(p\\bar p) \\rightarrow Q\\bar Q\\gam +X$ (for $Q=t,b$), at Next-to-Leading Order (NLO) in Quantum Chromodynamics (QCD). We study the impact of NLO QCD corrections on the total cross section and several differential distributions at both the Tevatron and the Large Hadron Collider (LHC). For $t\\bar t\\gam$ production we observe a sizeable reduction of the renormalization and factorization scale dependence when the NLO QCD corrections are included, while for $b\\bar b\\gam$ production a considerable scale dependence still persists at NLO in QCD. This is consistent with what emerges in similar processes involving $b$ quarks and vector bosons and we explain its origin in detail. For $b\\bar b\\gam$ production we study both the case in which at least one $b$ jet and the case in which at least two $b$ jets are observed. We perform the $b\\bar b\\gam$ calculation using the Four Flavor Number Scheme (4FNS) and compare the case where at least one $b$ jet is observed with the corresponding results from the Five Flavor Number Scheme (5FNS) calculation. Finally we compare our results for $p\\bar p \\rightarrow \\gam+b+X$ with the Tevatron data.

  12. A Measurement of the Mass of the Top Quark in Lepton + Jets Events at CDF

    SciTech Connect (OSTI)

    Brubaker, Erik Matthews

    2004-12-01

    This document presents a measurement of the top quark mass using the CDF run II detector at Fermilab. Colliding beams of protons and anti-protons at Fermilab's Tevatron ({radical}s = 1.96 TeV) produce top/anti-top pairs, which decay to W{sup +}W{sup -} b{bar b}; events are selected where one W decays hadronically, and one W decays to either e or {mu} plus a neutrino. The data sample was collected between March 2002 and September 2003, and corresponds to an integrated luminosity of approximately 162 pb{sup -1}. Thirty-seven candidate t{bar t} events are found with at least one b jet identified by its displaced vertex. In each event, the best fit top quark invariant mass is determined by minimizing a {chi}{sup 2} for the overconstrained kinematic system. A likelihood fit of the reconstructed masses in the data sample to distributions from simulated signal and background events gives a top mass of 174.9{sub -7.7}{sup +7.1}(stat.) {+-} 6.5(syst.) GeV/c{sup 2}. The dominant systematic error is due to uncertainties in the jet energy measurements.

  13. Quark-gluon plasma in the early Universe and in ultra-relativistic heavy-ion collisions

    SciTech Connect (OSTI)

    Greco, V.

    2014-05-09

    We briefly give an elementary introduction to the expansion of the Early Universe till when the phase transition of the quark-gluon plasma to a hadronic matter takes place. Then we describe some main element of the study of QGP by mean of ultra-relativistic heavy-ion collisions (uRHIC's)

  14. On the determination of the polarized parton distribution in the (x,Q2)-plane: a relativistic quark exchange approach

    SciTech Connect (OSTI)

    Yazdanpanah, M.M.; Modarres, M.

    2005-05-06

    We perform a next-to-leading order QCD analysis of polarized distribution functions of proton in the (x,Q2)-plane within the scheme of the radiative parton model. The flavor-broken light sea quark distributions is investigated and a comparison is made with the corresponding available experimental data.

  15. Measurement of the top-quark mass in the fully hadronic decay channel from ATLAS data at √s=7 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Khalek, S. Abdel; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; et al

    2015-04-23

    In this study, the mass of the top quark is measured in a data set corresponding to 4.6 fb-1 of proton–proton collisions with centre-of-mass energy √s=7 TeV collected by the ATLAS detector at the LHC. Events consistent with hadronic decays of top–antitop quark pairs with at least six jets in the final state are selected. The substantial background from multijet production is modelled with data-driven methods that utilise the number of identified b-quark jets and the transverse momentum of the sixth leading jet, which have minimal correlation. The top-quark mass is obtained from template fits to the ratio of three-jetmore » to dijet mass. The three-jet mass is calculated from the three jets produced in a top-quark decay. Using these three jets the dijet mass is obtained from the two jets produced in the W boson decay. The top-quark mass obtained from this fit is thus less sensitive to the uncertainty in the energy measurement of the jets. A binned likelihood fit yields a top-quark mass of mt=175.1±1.4(stat.) ±1.2(syst.) GeV.« less

  16. Measurement of the top quark mass using the template method in the lepton plus jets channel with in situ W ---> j j calibration at CDF-II

    SciTech Connect (OSTI)

    Adelman, Jahred A.; Arguin, J.F.; Bellettini, G.; Brubaker, E.; Budagov, J.; Chlachidze, G.; Demortier, L.; Gibson, A.; Kim, S.; Kim, Y.K.; Maruyama, T.; Sato, K.; Shochet, M.; Sinervo, P.; Tomura, T.; Velev, G.; Xie, S.; Yang, U.K.; /Chicago U. /Toronto U. /INFN, Pisa /Dubna, JINR /Rockefeller U. /LBL, Berkeley /Tsukuba U. /Fermilab

    2006-05-01

    We report an updated measurement of the top quark mass in the lepton plus jets channel of t{bar t} events from p{bar p} collisions at {radical}s = 1.96 TeV. This measurement uses a dataset with integrated luminosity of 680 pb{sup -1}, containing 360 t{bar t} candidates separated into four subsamples. A top quark mass is reconstructed for each event by using energy and momentum constraints on the top quark pair decay products. We also employ the reconstructed mass of hadronic W boson decays W {yields} jj to constrain in situ the largest systematic uncertainty of the top quark mass measurement: the jet energy scale. Monte Carlo templates of the reconstructed top quark and W boson mass are produced as a function of the true top quark mass and the jet energy scale. The distribution of reconstructed top quark and W boson mass in the data are compared to the Monte Carlo templates using a likelihood fit to obtain: M{sub top} = 173.4 {+-} 2.8 GeV/c{sup 2}.

  17. Measurement of the top-quark mass in the fully hadronic decay channel from ATLAS data at √s=7 TeV

    SciTech Connect (OSTI)

    Aad, G.; Abbott, B.; Abdallah, J.; Khalek, S. Abdel; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adamczyka, L.; Adams, D. L.; Adelman, J.; Adomeit, S.; Adye, T.

    2015-04-23

    In this study, the mass of the top quark is measured in a data set corresponding to 4.6 fb-1 of proton–proton collisions with centre-of-mass energy √s=7 TeV collected by the ATLAS detector at the LHC. Events consistent with hadronic decays of top–antitop quark pairs with at least six jets in the final state are selected. The substantial background from multijet production is modelled with data-driven methods that utilise the number of identified b-quark jets and the transverse momentum of the sixth leading jet, which have minimal correlation. The top-quark mass is obtained from template fits to the ratio of three-jet to dijet mass. The three-jet mass is calculated from the three jets produced in a top-quark decay. Using these three jets the dijet mass is obtained from the two jets produced in the W boson decay. The top-quark mass obtained from this fit is thus less sensitive to the uncertainty in the energy measurement of the jets. A binned likelihood fit yields a top-quark mass of mt=175.1±1.4(stat.) ±1.2(syst.) GeV.

  18. Search for pair-produced vector-like B quarks in proton-proton collisions at $\\sqrt{s}$ = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-07-28

    A search for the production of a heavy B quark, having electric charge -1/3 and vector couplings to W, Z, and H bosons, is carried out using proton-proton collision data recorded at the CERN LHC by the CMS experiment, corresponding to an integrated luminosity of 19.7 fb-1 . The B quark is assumed to be pair-produced and to decay in one of three ways: to tW, bZ, or bH. The search is carried out in final states with one, two, and more than two charged leptons, as well as in fully hadronic final states. Each of the channels in the exclusive final-state topologies is designed to be sensitive to specific combinations of the B quark-antiquark pair decays. The observed event yields are found to be consistent with the standard model expectations in all the fi- nal states studied. Our statistical combination of these results was performed and upper limits were set on the cross section of the strongly produced B quark-antiquark pairs as a function of the B quark mass. Additionally, lower limits on the B quark mass between 740 and 900 GeV are set at a 95% confidence level, depending on the values of the branching fractions of the B quark to tW, bZ, and bH. Overall, these limits are the most stringent to date.

  19. Jet energy loss in the quark-gluon plasma by stream instabilities

    SciTech Connect (OSTI)

    Mannarelli, Massimo; Manuel, Cristina; Gonzalez-Solis, Sergi; Strickland, Michael

    2010-04-01

    We study the evolution of the plasma instabilities induced by two jets of particles propagating in opposite directions and crossing a thermally equilibrated non-Abelian plasma. In order to simplify the analysis we assume that the two jets of partons can be described with uniform distribution functions in coordinate space and by Gaussian distribution functions in momentum space. We find that while crossing the quark-gluon plasma, the jets of particles excite unstable chromomagnetic and chromoelectric modes. These fields interact with the particles (or hard modes) of the plasma inducing the production of currents; thus, the energy lost by the jets is absorbed by both the gauge fields and the hard modes of the plasma. We compare the outcome of the numerical simulations with the analytical calculation performed assuming that the jets of particles can be described by a tsunamilike distribution function. We find qualitative and semiquantitative agreement between the results obtained with the two methods.

  20. Heavy Quark and Neutrino Physics. Final report, 2011-2-14

    SciTech Connect (OSTI)

    Horton-Smith, Glenn A.; Bolton, Timothy; Ivanov, Andrew; Maravin, Yurii; Ratra, Bharat

    2014-07-21

    This final closeout report covers research supported by the ''Heavy Quark and Neutrino Physics'' grant at Kansas State University during the grant's last renewal period, November 1, 2011, through April 30, 2014. The report begins with an overview of the group, its goals and activities, and personnel. Then summaries are given of achievements in each of the three frontiers: Energy Frontier research in the D0 and CMS experiments; Intensity Frontier research in the Double Chooz and ArgoNeuT experiments as well as research and development for MicroBooNE and LBNE; and Cosmic Frontier and Theoretical research. The report concludes with a list of publications supported by this grant in which our group made a significant contribution during the reporting period, followed by a list of students partially or fully supported by the grant who were awarded a PhD during this period.

  1. Search for the associated production of the Higgs boson with a top-quark pair

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2014-10-14

    Our search for the standard model Higgs boson produced in association with a top-quark pair (ttH) is presented, using data samples corresponding to integrated luminosities of up to 5.1 fb-1 and 19.7 fb-1 collected in pp collisions at center-of-mass energies of 7 TeV and 8 TeV respectively. The search is based on the following signatures of the Higgs boson decay: H → hadrons, H → photons, and H → leptons. These results are characterized by an observed ttH signal strength relative to the standard model cross section, µ = σ/σSM, under the assumption that the Higgs boson decays as expectedmore » in the standard model. The best fit value is µ = 2.8 ± 1.0 for a Higgs boson mass of 125.6 GeV« less

  2. Quark-hadron duality in the free neutron F2 structure function

    SciTech Connect (OSTI)

    Niculescu, Gabriel

    2015-09-01

    The Thomas Jefferson National Accelerator Facility (JLab) experiment BONuS used a novel spectator-tagging technique to measure the inclusive electron-free neutron scattering cross section and extract the F2 structure function. This data was used to reconstruct moments of F2 in the three prominent resonance region and the moments integrated over the entire resonance region. Comparisons of the experimental results with moments obtained from global parton distribution function parametrization seem to suggest that the quark-hadron duality hypothesis holds locally for the neutron in the second and third resonance regions down to Q2 of 1 GeV2; with up to 20% violations observed in the first resonance region.

  3. The discovery of the b quark at Fermilab in 1977: The experiment coordinator`s story

    SciTech Connect (OSTI)

    Yoh, J.

    1997-12-01

    I present the history of the discovery of the Upsilon ({Upsilon}) particle (the first member of the b-quark family to be observed) at Fermilab in 1977 by the CFS (Columbia-Fermilab-Stony Brook collaboration) E288 experiment headed by Leon Lederman. We found the first evidence of the {Upsilon} in November 1976 in an early phase of E288. The subsequent discovery in the spring of 1977 resulted from an upgraded E288 the {mu}{mu}II phase, optimized for dimuons, with about 100 times the sensitivity of the previous investigatory dimuon phase (which had been optimized for dielectrons). The events leading to the discovery, the planning of {mu}{mu}II and the running, including a misadventure (the infamous Shunt Fire of May 1977), are described. Some discussions of the aftermath, a summary, and an acknowledgement list end this brief historical note.

  4. Precision measurement of the top quark mass from dilepton events at CDF II

    SciTech Connect (OSTI)

    Abulencia, A.; Adelman, J.; Affolder, T.; Akimoto, T.; Albrow, M.G.; Ambrose, D.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; Annovi, A.; /Taiwan, Inst. Phys. /Argonne /Barcelona, IFAE /Baylor U. /INFN, Bologna /Bologna U. /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara

    2006-12-01

    We report a measurement of the top quark mass, M{sub t}, in the dilepton decay channel of t{bar t} {yields} b{ell}{prime}{sup +} {nu}{sub {ell}}, {bar b}{ell}{sup -}{bar {nu}}{sub {ell}} using an integrated luminosity of 1.0 fb{sup -1} of p{bar p} collisions collected with the CDF II detector. We apply a method that convolutes a leading-order matrix element with detector resolution functions to form event-by-event likelihoods; we have enhanced the leading-order description to describe the effects of initial-state radiation. The joint likelihood is the product of the likelihoods from 78 candidate events in this sample, which yields a measurement of M{sub t} = 164.5 {+-} 3.9(stat.) {+-} 3.9(syst.) GeV/c{sup 2}, the most precise measurement of M{sub t} in the dilepton channel.

  5. First Measurement of the Fraction of Top Quark Pair Production Through Gluon-Gluon Fusion

    SciTech Connect (OSTI)

    Collaboration, CDF; Aaltonen, T.

    2007-12-01

    We present the first measurement of {sigma}(gG {yields} t{bar t})/{sigma}(p{bar p} {yields} t{bar t}). We use 0.96 fb{sup -1} of {radical}s = 1.96 TeV p{bar p} collision data recorded with the CDF II detector at Fermilab. We identify the candidate t{bar t} events with a high-energy charged lepton, a neutrino candidate, and four or more jets with at least one identified as originating from a b quark. Using charged particles with low transverse momentum in t{bar t} events, we find {sigma}(gg {yields} t{bar t})/{sigma}(p{bar p} {yields} t{bar t}) = 0.07 {+-} 0.14(stat) {+-} 0.07(syst), in agreement with the standard model NLO prediction of 0.15 {+-} 0.05.

  6. Search for Violation of Lorentz Invariance in Top Quark Pair Production and Decay

    SciTech Connect (OSTI)

    Abazov V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Aoki, M.; Askew, A.; Atkins, S.; Augsten, K.; Avila, C.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Bean, A.; Begalli, M.; Bellantoni, L.; Berger, M. S.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besancon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatia, S.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; Boos, E. E.; Borissov, G.; Bose, T.; Brandt, A.; Brandt, O.; Brock, R.; Brooijmans, G.; Bross, A.; Brown, D.; Brown, J.; Bu, X. B.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Buszello, C. P.; Camacho-Perez, E.; Casey, B. C. K.; Castilla-Valdez, H.; Caughron, S.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chapon, E.; Chen, G.; Chevalier-Thery, S.; Cho, D. K.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M. -C.; Croc, A.; Cutts, D.; Das, A.; Davies, G.; de Jong, S. J.; De La Cruz-Burelo, E.; Deliot, F.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Ding, P. F.; Dominguez, A.; Dubey, A.; Dudko, L. V.; Duggan, D.; Duperrin, A.; Dutt, S.; Dyshkant, A.; Eads, M.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Enari, Y.; Evans, H.; Evdokimov, A.; Evdokimov, V. N.; Facini, G.; Feng, L.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Garcia-Bellido, A.; Garcia-Gonzalez, J. A.; Garcia-Guerra, G. A.; Gavrilov, V.; Gay, P.; Geng, W.; Gerbaudo, D.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Golovanov, G.; Goussiou, A.; Grannis, P. D.; Greder, S.; Greenlee, H.; Grenier, G.; Gris, Ph.; Grivaz, J. -F.; Grohsjean, A.; Gruenendahl, S.; Gruenewald, M. W.; Guillemin, T.; Gutierrez, G.; Gutierrez, P.; Haas, A.; Hagopian, S.; Haley, J.; Han, L.; Harder, K.; Harel, A.; Hauptman, J. M.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hoeneisen, B.; Hohlfeld, M.; Howley, I.; Hubacek, Z.; Hynek, V.; Iashvili, I.; Ilchenko, Y.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffre, M.; Jayasinghe, A.; Jesik, R.; Johns, K.; Johnson, E.; Johnson, M.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; Juste, A.; Kaadze, K.; Kajfasz, E.; Karmanov, D.; Kasper, P. A.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Kiselevich, I.; Kohli, J. M.; Kostelecky, V. A.; Kozelov, A. V.; Kraus, J.; Kulikov, S.; Kumar, A.; Kupco, A.; Kurca, T.; Kuzmin, V. A.; Lammers, S.; Landsberg, G.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lellouch, J.; Li, H.; Li, L.; Li, Q. Z.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, H.; Liu, Y.; Lobodenko, A.; Lokajicek, M.; de Sa, R. Lopes; Lubatti, H. J.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Madar, R.; Magana-Villalba, R.; Malik, S.; Malyshev, V. L.; Maravin, Y.; Martinez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; et al.

    2012-06-27

    Using data collected with the D0 detector at the Fermilab Tevatron Collider, corresponding to 5.3 fb{sup -1} of integrated luminosity, we search for violation of Lorentz invariance by examining the t{bar t} production cross section in lepton+jets final states. We quantify this violation using the standard-model extension framework, which predicts a dependence of the t{bar t} production cross section on sidereal time as the orientation of the detector changes with the rotation of the Earth. Within this framework, we measure components of the matrices (c{sub Q}){sub {mu}{nu}33} and (c{sub U}){sub {mu}{nu}33} containing coefficients used to parametrize violation of Lorentz invariance in the top quark sector. Within uncertainties, these coefficients are found to be consistent with zero.

  7. Search for the associated production of the Higgs boson with a top-quark pair

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2014-09-16

    A search for the standard model Higgs boson produced in association with a top-quark pair (t?tH) is presented, using data samples corresponding to integrated luminosities of up to 5.1 fb? and 19.7 fb? collected in pp collisions at center-of-mass energies of 7 TeV and 8 TeV respectively. The search is based on the following signatures of the Higgs boson decay: H ? hadrons, H ? photons, and H ? leptons. The results are characterized by an observed t?tH signal strength relative to the standard model cross section, ?=?/?SM, under the assumption that the Higgs boson decays as expected in the standard model. The best fit value is ? = 2.8 1.0 for a Higgs boson mass of 125.6 GeV.

  8. Search for the associated production of the Higgs boson with a top-quark pair

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2014-10-14

    Our search for the standard model Higgs boson produced in association with a top-quark pair (ttH) is presented, using data samples corresponding to integrated luminosities of up to 5.1 fb-1 and 19.7 fb-1 collected in pp collisions at center-of-mass energies of 7 TeV and 8 TeV respectively. The search is based on the following signatures of the Higgs boson decay: H → hadrons, H → photons, and H → leptons. These results are characterized by an observed ttH signal strength relative to the standard model cross section, µ = σ/σSM, under the assumption that the Higgs boson decays as expected in the standard model. The best fit value is µ = 2.8 ± 1.0 for a Higgs boson mass of 125.6 GeV

  9. Search for the associated production of the Higgs boson with a top-quark pair

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2014-09-16

    A search for the standard model Higgs boson produced in association with a top-quark pair (t?tH) is presented, using data samples corresponding to integrated luminosities of up to 5.1 fb? and 19.7 fb? collected in pp collisions at center-of-mass energies of 7 TeV and 8 TeV respectively. The search is based on the following signatures of the Higgs boson decay: H ? hadrons, H ? photons, and H ? leptons. The results are characterized by an observed t?tH signal strength relative to the standard model cross section, ?=?/?SM, under the assumption that the Higgs boson decays as expected in themorestandard model. The best fit value is ? = 2.8 1.0 for a Higgs boson mass of 125.6 GeV.less

  10. Search for single top-quark production via flavour-changing neutral currents at 8 TeV with the ATLAS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; et al

    2016-01-29

    A search for single top-quark production via flavour-changing neutral current processes from gluon plus up- or charm-quark initial states in proton–proton collisions at the LHC is presented. Data collected with the ATLAS detector in 2012 at a centre-of-mass energy of 8 TeV and corresponding to an integrated luminosity of 20.3 fb–1 are used. Furthermore, candidate events for a top quark decaying into a lepton, a neutrino and a jet are selected and classified into signal- and background-like candidates using a neural network.

  11. Measurement of single top quark production in the tau+jets channnel using boosted decision trees at D0

    SciTech Connect (OSTI)

    Liu, Zhiyi; ,

    2009-12-01

    The top quark is the heaviest known matter particle and plays an important role in the Standard Model of particle physics. At hadron colliders, it is possible to produce single top quarks via the weak interaction. This allows a direct measurement of the CKM matrix element V{sub tb} and serves as a window to new physics. The first direct measurement of single top quark production with a tau lepton in the final state (the tau+jets channel) is presented in this thesis. The measurement uses 4.8 fb{sup -1} of Tevatron Run II data in p{bar p} collisions at {radical}s = 1.96 TeV acquired by the D0 experiment. After selecting a data sample and building a background model, the data and background model are in good agreement. A multivariate technique, boosted decision trees, is employed in discriminating the small single top quark signal from a large background. The expected sensitivity of the tau+jets channel in the Standard Model is 1.8 standard deviations. Using a Bayesian statistical approach, an upper limit on the cross section of single top quark production in the tau+jets channel is measured as 7.3 pb at 95% confidence level, and the cross section is measured as 3.4{sub -1.8}{sup +2.0} pb. The result of the single top quark production in the tau+jets channel is also combined with those in the electron+jets and muon+jets channels. The expected sensitivity of the electron, muon and tau combined analysis is 4.7 standard deviations, to be compared to 4.5 standard deviations in electron and muon alone. The measured cross section in the three combined final states is {sigma}(p{bar p} {yields} tb + X,tqb + X) = 3.84{sub -0.83}{sup +0.89} pb. A lower limit on |V{sub tb}| is also measured in the three combined final states to be larger than 0.85 at 95% confidence level. These results are consistent with Standard Model expectations.

  12. Search for t-Channel Single Top Quark Production in p anti-p Collisions at 1.96 TeV

    SciTech Connect (OSTI)

    Perea, Philip Michael

    2006-06-01

    I have performed a search for t-channel single top quark production in p{bar p} collisions at 1.96 TeV on a 366 pb{sup -1} dataset collected with the D0 detector from 2002-2005. The analysis is restricted to the leptonic decay of the W boson from the top quark to an electron or muon, tq{bar b} {yields} lv{sub l}b q{bar b} (l = e,{mu}). A powerful b-quark tagging algorithm derived from neural networks is used to identify b jets and significantly reduce background. I further use neural networks to discriminate signal from background, and apply a binned likelihood calculation to the neural network output distributions to derive the final limits. No direct observation of single top quark production has been made, and I report expected/measured 95% confidence level limits of 3.5/8.0 pb.

  13. Search for a Heavy Top-Like Quark in $p\\bar{p}$ Collisions at ${\\surd}s = 1.96$~TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2011-07-01

    We present the results of a search for pair production of a heavy top-like (t') quark decaying to W q final states using data corresponding to an integrated luminosity of 5.6 fb{sup -1} collected by the CDF II detector in p{anti p} collisions at {radical}{ovr s} = 1.96 TeV. We perform parallel searches for t' {yields} W b and t' {yields} W q (where q is a generic down-type quark) in events containing a lepton and four or more jets. By performing a fit to the two-dimensional distribution of total transverse energy versus reconstructed t' quark mass, we set upper limits on the t'{anti t}' production cross section and exclude a standard model fourth-generation t' quark decaying to W b (W q) with mass below 358 (340) GeV/c{sup 2} at 95% CL.

  14. Search for a Vectorlike Quark with Charge 2/3 in t+Z Events from pp Collisions at √s=7 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Fabjan, C.; Friedl, M.; et al

    2011-12-29

    A search for pair-produced heavy vectorlike charge-2/3 quarks, T, in pp collisions at a center-of-mass energy of 7 TeV, is performed with the CMS detector at the LHC. Events consistent with the flavor-changing-neutral-current decay of a T quark to a top quark and a Z boson are selected by requiring two leptons from the Z-boson decay, as well as an additional isolated charged lepton. In a data sample corresponding to an integrated luminosity of 1.14 fb⁻¹, the number of observed events is found to be consistent with the standard model background prediction. Assuming a branching fraction of 100% for themore » decay T→tZ, a T quark with a mass less than 475 GeV/c² is excluded at the 95% confidence level.« less

  15. Search for a Vectorlike Quark with Charge 2/3 in t+Z Events from pp Collisions at √s=7 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Fabjan, C.; Friedl, M.; et al

    2011-12-29

    A search for pair-produced heavy vectorlike charge-2/3 quarks, T, in pp collisions at a center-of-mass energy of 7 TeV, is performed with the CMS detector at the LHC. Events consistent with the flavor-changing-neutral-current decay of a T quark to a top quark and a Z boson are selected by requiring two leptons from the Z-boson decay, as well as an additional isolated charged lepton. In a data sample corresponding to an integrated luminosity of 1.14 fb⁻¹, the number of observed events is found to be consistent with the standard model background prediction. Assuming a branching fraction of 100% for themore »decay T→tZ, a T quark with a mass less than 475 GeV/c² is excluded at the 95% confidence level.« less

  16. Tomography of quark gluon plasma at energies available at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC)

    SciTech Connect (OSTI)

    Gossiaux, P. B.; Bierkandt, R.; Aichelin, J.

    2009-04-15

    Using the recently published model [Gossiaux and Aichelin, Phys. Rev. C 78, 014904 (2008)] for the collisional energy loss of heavy quarks in a quark gluon plasma (QGP), based on perturbative QCD (pQCD) with a running coupling constant, we study the interaction between heavy quarks and plasma particles in detail. We discuss correlations between the simultaneously produced c and c quarks, study how central collisions can be experimentally selected, predict observable correlations, and extend our model to the energy domain of the Large Hadron Collider (LHC). We finally compare the predictions of our model with that of other approaches such as anti-de Sitter/conformal field theory (AdS/CFT)

  17. Combination of searches for anomalous top quark couplings with 5.4 fb(-1) of p(p)over-bar collisions

    SciTech Connect (OSTI)

    Abazov V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Aoki, M.; Askew, A.; Atkins, S.; Augsten, K.; Avila, C.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Bean, A.; Begalli, M.; Bellantoni, L.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besancon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatia, S.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; Boos, E. E.; Borissov, G.; Bose, T.; Brandt, A.; Brandt, O.; Brock, R.; Brooijmans, G.; Bross, A.; Brown, D.; Brown, J.; Bu, X. B.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Buszello, C. P.; Camacho-Perez, E.; Casey, B. C. K.; Castilla-Valdez, H.; Caughron, S.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chapon, E.; Chen, G.; Chevalier-Thery, S.; Cho, D. K.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M. -C.; Croc, A.; Cutts, D.; Das, A.; Davies, G.; de Jong, S. J.; De La Cruz-Burelo, E.; Deliot, F.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Ding, P. F.; Dominguez, A.; Dubey, A.; Dudko, L. V.; Duggan, D.; Duperrin, A.; Dutt, S.; Dyshkant, A.; Eads, M.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Enari, Y.; Evans, H.; Evdokimov, A.; Evdokimov, V. N.; Facini, G.; Feng, L.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Garcia-Bellido, A.; Garcia-Gonzalez, J. A.; Garcia-Guerra, G. A.; Gavrilov, V.; Gay, P.; Geng, W.; Gerbaudo, D.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Golovanov, G.; Goussiou, A.; Grannis, P. D.; Greder, S.; Greenlee, H.; Grenier, G.; Gris, Ph; Grivaz, J-F; Grohsjean, A.; Gruenendahl, S.; Gruenewald, M. W.; Guillemin, T.; Gutierrez, G.; Gutierrez, P.; Haas, A.; Hagopian, S.; Haley, J.; Han, L.; Harder, K.; Harel, A.; Hauptman, J. M.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hoeneisen, B.; Hohlfeld, M.; Howley, I.; Hubacek, Z.; Hynek, V.; Lashvili, I.; Ilchenko, Y.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffe, M.; Jayasinghe, A.; Jesik, R.; Johns, K.; Johnson, E.; Johnson, M.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; Juste, A.; Kaadze, K.; Kajfasz, E.; Karmanov, D.; Kasper, P. A.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Kiselevich, I.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kulikov, S.; Kumar, A.; Kupco, A.; Kurca, T.; Kuzmin, V. A.; Lammers, S.; Landsberg, G.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lellouch, J.; Li, H.; Li, L.; Li, Q. Z.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, H.; Liu, Y.; Lobodenko, A.; Lokajicek, M.; de Sa, R. Lopes; Lubatti, H. J.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Madar, R.; Magana-Villalba, R.; Malik, S.; Malyshev, V. L.; Maravin, Y.; Martinez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Meyer, A.; Meyer, J.; et al.

    2012-07-09

    We present measurements of the tWb coupling form factors using information from electroweak single top quark production and from the helicity of W bosons from top quark decays in t{bar t} events. We set upper limits on anomalous tWb coupling form factors using data collected with the D0 detector at the Tevatron p{bar p} collider corresponding to an integrated luminosity of 5.4 fb{sup -1}.

  18. Search for Pair Production of Scalar Top Quarks Decaying to a tau Lepton and a b Quark in ppbar Collisions at sqrt{s}=1.96 TeV

    SciTech Connect (OSTI)

    Brigliadori, L.; Zheng, Y.; Zucchelli, S.; /Taiwan, Inst. Phys. /Bologna U. /Argonne /Barcelona, IFAE /Baylor U., Math. Dept. /Bologna U. /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara /Cantabria U., Santander /Carnegie Mellon U.

    2008-02-01

    We present the results of a search for pair production of scalar top quarks ({tilde t}{sub 1}) in an R-parity violating supersymmetric scenario using 322 pb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV collected by the upgraded Collider Detector at Fermilab. We assume each {tilde t}{sub 1} decays into a {tau} lepton and a b quark with a branching ratio {beta}, and that the final state contains either an electron or a muon from a leptonic {tau} decay, a hadronically decaying {tau} lepton, and two or more jets. Two candidate events pass our final selection criteria, consistent with the expectation from standard model processes. We present upper limits on the cross section times branching ratio squared {sigma}({tilde t}{sub 1}{bar {tilde t}}{sub 1}) x {beta}{sup 2} as a function of the stop mass m({tilde t}{sub 1}). Assuming {beta} = 1, we set a 95% confidence level limit m({tilde t}{sub 1}) > 153 GeV=c{sup 2} obtained using a next-to-leading order cross section. These limits are also fully applicable to the case of a pair produced third generation scalar leptoquark decaying into a {tau} lepton and a b quark.

  19. R-parity violating effects in top quark flavor-changing neutral-current production at LHC

    SciTech Connect (OSTI)

    Cao Junjie; Heng Zhaoxia; Yang Jinmin; Wu Lei

    2009-03-01

    In the minimal supersymmetric model the R-parity violating top quark interactions, which are so far weakly constrained, can induce various flavor-changing neutral-current (FCNC) productions for the top quark at the large hadron collider (LHC). In this work we assume the presence of the B-violating couplings and examine their contributions to the FCNC productions proceeding through the parton processes cg{yields}t, gg{yields}tc, cg{yields}t{gamma}, cg{yields}tZ and cg{yields}th. We find that all these processes can be greatly enhanced relative to the R-parity preserving predictions. In the parameter space allowed by current experiments, all the production channels except cg{yields}th can reach the 3{sigma} sensitivity, in contrast to the R-parity preserving case in which only cg{yields}t can reach the 3{sigma} sensitivity.

  20. CKM-suppressed top quark decays t{yields}s(d)+W in the standard model and beyond

    SciTech Connect (OSTI)

    Diaz-Cruz, J. L.; Gaitan-Lozano, R.; Castro, G. Lopez; Pagliarone, C. E.

    2008-05-01

    As it is well known, top quark decays are of particular interest as a means to test the standard model (SM) predictions, these include the dominant (t{yields}b+W), the Cabibbo-Kobayashi-Maskawa (CKM)-suppressed process t{yields}cWW, and the rare decays (t{yields}cV, cVV, c{phi}{sup 0}, bWZ). As all of them are highly suppressed, they become an excellent window to probe the predictions of theories beyond the SM. In this paper, we evaluate the corrections from new physics to the CKM-suppressed SM top quark decay t{yields}q+W(q=d,s), both within an effective model with right-handed currents and for the minimal SUSY extension of the SM. We also discuss the perspectives to probe those predictions at the International Linear Collider.

  1. Measurement of the top-quark mass in the tt dilepton channel using the full CDF Run II data set

    SciTech Connect (OSTI)

    Aaltonen, T.

    2015-08-06

    We present a measurement of the top-quark mass in events containing two leptons (electrons or muons) with a large transverse momentum, two or more energetic jets, and a transverse-momentum imbalance. We use the full proton-antiproton collision data set collected by the CDF experiment during the Fermilab Tevatron Run II at center-of-mass energy ?s = 1.96 TeV, corresponding to an integrated luminosity of 9.1 fb1. A special observable is exploited for an optimal reduction of the dominant systematic uncertainty, associated with the knowledge of the absolute energy of the hadronic jets. The distribution of this observable in the selected events is compared to simulated distributions of tt dilepton signal and background. We measure a value for the top-quark mass of 171.51.9 (stat)2.5 (syst) GeV/c2.

  2. Probing the Quark Sea and Gluons: the Electron-Ion Collider Projects

    SciTech Connect (OSTI)

    Rolf Ent

    2012-04-01

    EIC is the generic name for the nuclear science-driven Electron-Ion Collider presently considered in the US. Such an EIC would be the worlds first polarized electron-proton collider, and the worlds first e-A collider. Very little remains known about the dynamical basis of the structure of hadrons and nuclei in terms of the fundamental quarks and gluons of Quantum Chromodynamics (QCD). A large community effort to sharpen a compelling nuclear science case for an EIC occurred during a ten-week program taking place at the Institute for Nuclear Theory (INT) in Seattle from September 13 to November 19, 2010. The critical capabilities of a stage-I EIC are a range in center-of-mass energies from 20 to 70 GeV and variable, full polarization of electrons and light ions (the latter both longitudinal and transverse), ion species up to A=200 or so, multiple interaction regions, and a high luminosity of about 10{sup 34} electron-nucleons per cm{sup 2} and per second. The physics program of such a stage-I EIC encompass inclusive measurements (ep/A{yields}e'+X), which require detection of the scattered lepon and/or the full scattered hadronic debris with high precision, semi-inclusive processes (ep/A{yields}e'+h+X), which require detection in coincidence with the scattered lepton of at least one (current or target region) hadron; and exclusive processes (ep/A{yields}e'+N'/A'+{gamma}/m), which require detection of all particles in the reaction. The main science themes of an EIC are to i) map the spin and spatial structure of quarks and gluons in nucleons, ii) discover the collective effects of gluons in atomic nuclei, and (iii) understand the emergence of hadronic matter from color charge. In addition, there are opportunities at an EIC for fundamental symmetry and nucleon structure measurements using the electroweak probe. To truly make headway to image the sea quarks and gluons in nucleons and nuclei, the EIC needs high luminosity over a range of energies as more exclusive scattering probabilities are small, and any integrated detector/interaction region design needs to provide uniform coverage to detect spectator and diffractive products. This is because e-p and even more e-A colliders have a large fraction of their science related to what happens to the nucleon or ion beams. As a result, the philosophy of integration of complex detectors into an extended interaction region faces challenging constraints. Designs feature crossing angles between the protons or heavy ions during collisions with electrons, to remove potential problems for the detector induced by synchrotron radiation. Designs allocate quite some detector space before the final-focus ion quads, at the cost of luminosity, given that uniform detection coverage is a must for deep exclusive and diffractive processes. The integrated EIC detector/interaction region design at JLab focused on establishing full acceptance for such processes over a wide range of proton energies (20-100 GeV) with well achievable interaction region magnets. The detector design at BNL uses the higher ion beam energies to achieve good detection efficiency for instance for protons following a DVCS reaction, for proton beam energies starting from 100 GeV. Following a recommendation of the 2007 US Nuclear Science Long-Range Planning effort, the DOE Office of Nuclear Physics (DOE/NP) has allocated accelerator R&D funds to lay the foundation for a polarized EIC. BNL, in association with JLab and DOE/NP, has also established a generic detector R&D program to address the scientific requirements for measurements at a future EIC.

  3. Effects of quark family nonuniversality in SU(3){sub c} x SU(4){sub L} x U(1){sub X} models

    SciTech Connect (OSTI)

    Nisperuza, Jorge L.; Sanchez, Luis A.

    2009-08-01

    Flavor changing neutral currents arise in the SU(3){sub c} x SU(4){sub L} x U(1){sub X} extension of the standard model because anomaly cancellation among the fermion families requires one generation of quarks to transform differently from the other two under the gauge group. In the weak basis the distinction between quark families is meaningless. However, in the mass eigenstates basis, the Cabibbo-Kobayashi-Maskawa mixing matrix motivates us to classify left-handed quarks in families. In this sense there are, in principle, three different assignments of quark weak eigenstates into mass eigenstates. In this work, by using measurements at the Z pole, atomic parity violation data, and experimental input from neutral meson mixing, we examine two different models without exotic electric charges based on the 3-4-1 symmetry, and address the effects of quark family nonuniversality on the bounds on the mixing angle between two of the neutral currents present in the models and on the mass scales M{sub Z{sub 2}} and M{sub Z{sub 3}} of the new neutral gauge bosons predicted by the theory. The heaviest family of quarks must transform differently in order to keep lower bounds on M{sub Z{sub 2}} and M{sub Z{sub 3}} as low as possible without violating experimental constraints.

  4. Top quark flavor-changing neutral-current decays and productions at LHC in the littlest Higgs model with T parity

    SciTech Connect (OSTI)

    Han Xiaofang; Wang Lei; Yang Jinmin

    2009-07-01

    In the littlest Higgs model with T-parity (LHT) the newly introduced mirror quarks have flavor-changing couplings with the standard model (SM) quarks and may enhance the flavor-changing neutral-current (FCNC) top-quark interactions which are extremely suppressed in the SM. In this work we perform a comprehensive study for the contributions of these mirror fermions to various top-quark FCNC decays and productions at the LHC, which includes the decays t{yields}cV (V=g, {gamma}, Z), t{yields}cgg and the productions proceeding through the parton processes cg{yields}t, gg{yields}tc, cg{yields}tg, cg{yields}t{gamma} and cg{yields}tZ. We find that although these FCNC processes can be greatly enhanced by the LHT contributions, they are hardly accessible at the LHC. Therefore, the LHT model may not cause the FCNC problem in the top-quark sector if the top-quark property is proved to be SM-like at the LHC.

  5. Search for the production of an excited bottom quark decaying to tW in proton-proton collisions at $\\sqrt{s} =$ 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-09-29

    Our search is presented for a singly produced excited bottom quark (b*) decaying to a top quark and a W boson in the all-hadronic, lepton+jets, and dilepton final states in proton-proton collisions at √s = 8 TeV recorded by the CMS experiment at the CERN LHC. Data corresponding to an integrated luminosity of 19.7 fb-1 are used. No significant excess of events is observed with respect to standard model expectations. We set limits at 95% confidence on the product of the b* quark production cross section and its branching fraction to tW. Furthermore, the cross section limits are interpreted for scenarios including left-handed, right-handed, and vector-like couplings of the b* quark and are presented in the two-dimensional coupling plane based on the production and decay coupling constants. The masses of the left-handed, right-handed, and vectorlike b* quark states are excluded at 95% confidence below 1390, 1430, and 1530 GeV, respectively, for benchmark couplings. This analysis gives the most stringent limits on the mass of the b* quark to date.

  6. Direct Photons at Low Transverse Momentum: A Signal for Quark-Gluon Plasma in pp Collisions at LHC

    SciTech Connect (OSTI)

    Liu Fuming; Werner, Klaus

    2011-06-17

    We investigate photon production in a scenario of quark-gluon plasma formation in proton-proton scattering at 7 TeV. It is shown that thermal photon yields increase quadratically with the charged particle multiplicity. This gives an enhanced weight to high multiplicity events, and leads to an important photon production even in minimum-bias events, where the thermal photons largely dominate over the prompt ones at transverse momentum values smaller than 10 GeV/c.

  7. Top quark pair production cross section in the lepton+jets channel using b-tagging at D0

    SciTech Connect (OSTI)

    Yoo, H.D.; /Brown U.

    2008-05-01

    The top quark pair production cross section measurement in the lepton+jets channel with b-tagging algorithm is described. About 900 pb{sup -1} data collected by the D0 detector at the Fermilab Tevatron are used for this analysis. In this thesis, event selection, background estimation, and cross section calculation are discussed in detail. In addition, calibration of the Luminosity Monitor readout electronics and a new b-tagging algorithm, the SLTNN tagger, are also discussed in this thesis.

  8. Measurements of the Neutron Longitudinal Spin Asymmetry A1n and Flavor Decomposition in the Valence Quark Region

    SciTech Connect (OSTI)

    Flay, David J.

    2014-08-01

    The current data for the nucleon-virtual photon longitudinal spin asymmetry A1 on the proton and neutron have shown that the ratio of the polarized-to-unpolarized down-quarkparton distribution functions,Dd=d, tends towards -1/2 at large x, in disagreement with the perturbative QCD prediction that Dd/d approaches 1 but more in line with constituent quark models. As a part of experiment E06-014 in Hall A of Jefferson Lab, double-spin asymmetries were measured in the scattering of a longitudinally polarized electron beam of energies 4.74 and 5.89 GeV from a longitudinally and transversely polarized 3He target in the deep inelastic scattering and resonance region, allowing for the extraction of the neutron asymmetry An1 and the ratios Dd/d and Du/u. We will discuss our analysis of the data and present results for A1 and g1/F1 on both 3He and the neutron, and the resulting quark ratios for the up and down quarks in the kinematic range of 0.2

  9. Exclusive B{yields}{rho}l{sup +}l{sup -} decay in the standard model with fourth-generation quarks

    SciTech Connect (OSTI)

    Zeynali, K.; Bashiry, V.

    2008-08-01

    We investigate the influence of the fourth generation of quarks on the branching ratio, the CP asymmetry, and the polarization asymmetries in B{yields}{rho}l{sup +}l{sup -} decay. Taking |V{sub t{sup '}}{sub d}V{sub t{sup '}}{sub b}|{approx}0.001 with phase about 10 deg., which is consistent with the sin2{phi}{sub 1} of the Cabibbo-Kobayashi-Maskawa matrix and the B{sub d} mixing parameter {delta}m{sub B{sub d}}, we obtain that for both ({mu},{tau}) channels the branching ratio is increased and the magnitude of CP asymmetry and polarization asymmetries decreased by the mass and mixing parameters of the 4th generation of quarks. These results can serve as a good tool to search for new physics effects, precisely, to search for the fourth generation of quarks (t{sup '},b{sup '}) via its indirect manifestations in loop diagrams.

  10. Search for dark matter in events with heavy quarks and missing transverse momentum in pp collisions with the ATLAS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.

    2015-02-24

    This article reports on a search for dark matter pair production in association with bottom or top quarks in 20.3 fb–1 of pp collisions collected at √s=8 TeV by the ATLAS detector at the LHC. Events with large missing transverse momentum are selected when produced in association with high-momentum jets of which one or more are identified as jets containing b-quarks. Final states with top quarks are selected by requiring a high jet multiplicity and in some cases a single lepton. The data are found to be consistent with the Standard Model expectations and limits are set on the massmore » scale of effective field theories that describe scalar and tensor interactions between dark matter and Standard Model particles. Limits on the dark-matter–nucleon cross-section for spin-independent and spin-dependent interactions are also provided. These limits are particularly strong for low-mass dark matter. Using a simplified model, constraints are set on the mass of dark matter and of a colored mediator suitable to explain a possible signal of annihilating dark matter.« less

  11. Search for pair production of scalar top quarks in jets and missing transverse energy channel with the D0 detector

    SciTech Connect (OSTI)

    Shamim, Mansoora; /Kansas State U.

    2008-05-01

    This dissertation describes a search for the pair production of scalar top quarks, {tilde t}{sub 1}, using a luminosity of 995 pb{sup -1} of data collected in p{bar p} collisions with the D0 detector at the Fermilab Tevatron Collider at a center-of-mass energy {radical}s = 1.96 TeV. Both scalar top quarks are assumed to decay into a charm quark and a neutralino, {tilde {chi}}{sub 1}{sup 0}, where {tilde {chi}}{sub 1}{sup 0} is the lightest supersymmetric particle. This leads to a final state with two acoplanar charm jets and missing transverse energy. The yield of such events in data is found to be consistent with the expectations from known standard model processes. Sets of {tilde t}{sub 1} and {tilde {chi}}{sub 1}{sup 0} masses are excluded at the 95% confidence level that substantially extend the domain excluded by previous searches. With the theoretical uncertainty on the {tilde t}{sub 1} pair production cross section taken into account, the largest limit for m{sub {tilde t}{sub 1}} is m{sub {tilde t}{sub 1}} > 150 GeV, for m{sub {tilde {chi}}{sub 1}{sup 0}} = 65 GeV.

  12. Shear viscosity of the quark-gluon plasma in a kinetic theory approach

    SciTech Connect (OSTI)

    Puglisi, A.; Plumari, S.; Scardina, F.; Greco, V.

    2014-05-09

    One of the main results of heavy ions collision (HIC) at relativistic energy experiments is the very small shear viscosity to entropy density ratio of the Quark-Gluon Plasma, close to the conjectured lower bound ?/s=1/4? for systems in the infinite coupling limit. Transport coefficients like shear viscosity are responsible of non-equilibrium properties of a system: Green-Kubo relations give us an exact expression to compute these coefficients. We compute shear viscosity numerically using Green-Kubo relation in the framework of Kinetic Theory solving the relativistic transport Boltzmann equation in a finite box with periodic boundary conditions. We investigate a system of particles interacting via anisotropic and energy dependent cross-section in the range of temperature of interest for HIC. Green-Kubo results are in agreement with Chapman-Enskog approximation while Relaxation Time approximation can underestimates the viscosity of a factor 2. The correct analytic formula for shear viscosity can be used to develop a transport theory with a fixed ?/s and have a comparison with physical observables like elliptic flow.

  13. Gluons and the quark sea at high energies: distributions, polarization, tomography

    SciTech Connect (OSTI)

    Boer, D.; Venugopalan, R.; Diehl, M.; Milner, R.; Vogelsang, W.; et al.

    2011-09-30

    This report is based on a ten-week program on Gluons and the quark sea at high-energies, which took place at the Institute for Nuclear Theory (INT) in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics (QCD). This report is organized around the following four major themes: (i) the spin and flavor structure of the proton, (ii) three dimensional structure of nucleons and nuclei in momentum and configuration space, (iii) QCD matter in nuclei, and (iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific opportunities presented by an EIC.

  14. Low and high energy phenomenology of quark-lepton complementarity scenarios

    SciTech Connect (OSTI)

    Hochmuth, Kathrin A. [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, D-80805 Munich (Germany); Rodejohann, Werner [Physik-Department, Technische Universitaet Muenchen, James-Franck-Strasse, D-85748 Garching (Germany)

    2007-04-01

    We conduct a detailed analysis of the phenomenology of two predictive seesaw scenarios leading to quark-lepton complementarity. In both cases we discuss the neutrino mixing observables and their correlations, neutrinoless double beta decay and lepton flavor violating decays such as {mu}{yields}e{gamma}. We also comment on leptogenesis. The first scenario is disfavored on the level of one to two standard deviations, in particular, due to its prediction for |U{sub e3}|. There can be resonant leptogenesis with quasidegenerate heavy and light neutrinos, which would imply sizable cancellations in neutrinoless double beta decay. The decays {mu}{yields}e{gamma} and {tau}{yields}{mu}{gamma} are typically observable unless the SUSY masses approach the TeV scale. In the second scenario leptogenesis is impossible. It is, however, in perfect agreement with all oscillation data. The prediction for {mu}{yields}e{gamma} is in general too large, unless the SUSY masses are in the range of several TeV. In this case {tau}{yields}e{gamma} and {tau}{yields}{mu}{gamma} are unobservable.

  15. Combination of CDF and D0 measurements of the $W$ boson helicity in top quark decays

    SciTech Connect (OSTI)

    Aaltonen, T.; Abazov, V.M.; Abbott, B.; Acharya, B.S.; Adams, M.; Adams, T.; Alexeev, G.D.; Alkhazov, G.; Alton, A.; Alvarez Gonzalez, B.; Alverson, G.; /Northeastern U. /INFN, Padua

    2012-02-01

    We report the combination of recent measurements of the helicity of the W boson from top quark decay by the CDF and D0 collaborations, based on data samples corresponding to integrated luminosities of 2.7-5.4 fb{sup -1} of p{bar p} collisions collected during Run II of the Fermilab Tevatron Collider. Combining measurements that simultaneously determine the fractions of W bosons with longitudinal (f{sub 0}) and right-handed (f{sub +}) helicities, we find f{sub 0} = 0.722 {+-} 0.081 [{+-} 0.062 (stat.) {+-} 0.052 (syst.)] and f{sub +} = -0.033 {+-} 0.046 [{+-} 0.034 (stat.) {+-} 0.031 (syst.)]. Combining measurements where one of the helicity fractions is fixed to the value expected in the standard model, we find f{sub 0} = 0.682 {+-} 0.057 [{+-} 0.035 (stat.) {+-} 0.046 (syst.)] and f{sub +} = ?0.015 {+-} 0.035 [{+-} 0.018 (stat.) {+-} 0.030 (syst.)]. The results are consistent with standard model expectations.

  16. A Z{sub 3} generalization of Pauli's principle, quark algebra and the Lorentz invariance

    SciTech Connect (OSTI)

    Kerner, Richard

    2012-09-24

    The fundamental difference between bosons and fermions is that they obey two alternative representations of the Z{sub 2} group, resulting in symmetric or anti-symmetric binary commutation relations. Our aim is to explore possibilities offered by ternary Z{sub 3} generalization commutation relations. This leads to cubic and ternary algebras which are a direct generalization of usual commutation relations, with Z{sub 3}-grading replacing the usual Z{sub 2}-grading. Properties and structure of such algebras are discussed, with special interest in a low-dimensional one, with two generators. Invariant cubic forms on such algebras are introduced, and it is shown how the SL(2,C) group arises naturally as the symmetry group preserving these forms. In the case of lowest dimension, with only two generators, it is shown how the cubic combinations of elements of the same Z{sub 3} grade behave like Lorentz spinors, while binary products of elements of this algebra with an element of the conjugate algebra behave like Lorentz vectors. The wave equation generalizing the Dirac operator to the Z{sub 3}-graded case is introduced, whose diagonalization leads to a third-order equation. The solutions of this equation cannot propagate because their exponents always contain non-oscillating real damping factor. We show how certain cubic products can propagate nevertheless. The model suggests the origin of the color SU(3) symmetry obeyed by quark states.

  17. Search for the production of single vector-like and excited quarks in the Wt final state in pp collisions at √s = 8 TeV with the ATLAS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; et al

    2016-02-17

    A search for vector-like quarks and excited quarks in events containing a top quark and a W boson in the final state is reported here. The search is based on 20.3 fb-1 of proton-proton collision data taken at the LHC at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector. Events with one or two leptons, and one, two or three jets are selected with the additional requirement that at least one jet contains a b-quark. Single-lepton events are also required to contain at least one large-radius jet from the hadronic decay of a high-pT W boson ormore » a top quark. No significant excess over the expected background is observed and upper limits on the cross-section times branching ratio for different vector-like quark and excited-quark model masses are derived. As a result, for the excited-quark production and decay to Wt with unit couplings, quarks with masses below 1500 GeV are excluded and coupling-dependent limits are set.« less

  18. Semi-inclusive charged-pion electroproduction off protons and deuterons: Cross sections, ratios, and access to the quark-parton model at low energies

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Asaturyan, R.; Ent, R.; Mkrtchyan, H.; Navasardyan, T.; Tadevosyan, V.; Adams, G. S.; Ahmidouch, A.; Angelescu, T.; Arrington, J.; Asaturyan, A.; et al

    2012-01-01

    A large set of cross sections for semi-inclusive electroproduction of charged pions (π±) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared W2 > 4 GeV2 and range in four-momentum transfer squared 2 < Q2 < 4 (GeV/c)2, and cover a range in the Bjorken scaling variable 0.2 < x < 0.6. The fractional energy of the pions spans a range 0.3 < z < 1, with small transverse momenta with respect to the virtual-photon direction, Pt2 < 0.2 (GeV/c)2. The invariant mass that goes undetected, Mx or W',more » is in the nucleon resonance region, W' < 2 GeV. The new data conclusively show the onset of quark-hadron duality in this process, and the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark → pion production mechanisms. The x, z and Pt2 dependences of several ratios (the ratios of favored-unfavored fragmentation functions, charged pion ratios, deuteron-hydrogen and aluminum-deuteron ratios for π+ and π-) have been studied. The ratios are found to be in good agreement with expectations based upon a high-energy quark-parton model description. We find the azimuthal dependences to be small, as compared to exclusive pion electroproduction, and consistent with theoretical expectations based on tree-level factorization in terms of transverse-momentum-dependent parton distribution and fragmentation functions. In the context of a simple model, the initial transverse momenta of d quarks are found to be slightly smaller than for u quarks, while the transverse momentum width of the favored fragmentation function is about the same as for the unfavored one, and both fragmentation widths are larger than the quark widths.« less

  19. Search for the Neutral Current Top Quark Decay t-->Zc Using Ratio of Z-Boson + 4 Jets to W-Boson + 4 Jets Production

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, Jahred A.; Akimoto, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, Dante E.; Anastassov, A.; Annovi, Alberto; Antos, Jaroslav; Apollinari, G.; Apresyan, A.; /Purdue U. /Waseda U.

    2009-05-01

    We have used the Collider Detector at Fermilab (CDF II) to search for the flavor-changing neutral-current (FCNC) top quark decay t {yields} Zc using a technique employing ratios of W and Z production, measured in p{bar p} data corresponding to an integrated luminosity of 1.52 fb{sup -1}. The analysis uses a comparison of two decay chains, p{bar p} {yields} t{bar t} {yields} WbWb {yields} {ell}{nu}bjjb and p{bar p} {yields} t{bar t} {yields} ZcWb {yields} {ell}{ell}cjjb, to cancel systematic uncertainties in acceptance, efficiency, and luminosity. We validate the modeling of acceptance and efficiency for lepton identification over the multi-year dataset using another ratio of W and Z production, in this case the observed ratio of inclusive production of W to Z bosons. To improve the discrimination against standard model backgrounds to top quark decays, we calculate the top quark mass for each event with two leptons and four jets assuming it is a t{bar t} event with one of the top quarks decaying to Zc. For additional background discrimination we require at least one jet to be identified as originating from a b-quark. No significant signal is found and we set an upper limit on the FCNC branching ratio Br(t {yields} Zc) using a likelihood constructed from the {ell}{ell}cjjb top quark mass distribution and the number of {ell}{nu}bjjb events. Limits are set as a function of the helicity of the Z boson produced in the FCNC decay. For 100% longitudinally polarized Z bosons we find limits of 8.3% and 9.3% (95% C.L.) depending on the assumptions regarding the theoretical top quark pair production cross-section.

  20. Determination of the top-quark pole mass using tt¯ + 1-jet events collected with the ATLAS experiment in 7TeV pp collisions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; et al

    2015-10-19

    In this study, the normalized differential cross section for top-quark pair production in association with at least one jet is studied as a function of the inverse of the invariant mass of the tt¯ + 1-jet system. This distribution can be used for a precise determination of the top-quark mass since gluon radiation depends on the mass of the quarks. The experimental analysis is based on proton-proton collision data collected by the ATLAS detector at the LHC with a centre-of-mass energy of 7 TeV corresponding to an integrated luminosity of 4.6 fb–1 . The selected events were identified using themore » lepton+jets top-quark-pair decay channel, where lepton refers to either an electron or a muon. The observed distribution is compared to a theoretical prediction at next-to-leading-order accuracy in quantum chromodynamics using the pole-mass scheme. With this method, the measured value of the top-quark pole mass, mpolet , is: mpolet = 173.7 ± 1.5(stat.) ± 1.4(syst.)+1.0–0.5(theory) GeV.« less

  1. Determination of the top-quark pole mass using tt¯ + 1-jet events collected with the ATLAS experiment in 7TeV pp collisions

    SciTech Connect (OSTI)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Adelman, J.; Adomeit, S.; Adye, T.; Agatonovic-Jovin, T.; Aguilar-Saavedra, J. A.; Agustoni, M.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akerstedt, H.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albrand, S.; Alconada Verzini, M. J.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Alimonti, G.; Alio, L.; Alison, J.; Allbrooke, B. M. M.; Allison, L. J.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Altheimer, A.; Alvarez Gonzalez, B.; Alviggi, M. G.; Amako, K.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amram, N.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Anduaga, X. S.; Angelidakis, S.; Angelozzi, I.; Anger, P.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Arabidze, G.; Arai, Y.; Araque, J. P.; Arce, A. T. H.; Arduh, F. A.; Arguin, J-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnal, V.; Arnold, H.; Arratia, M.; Arslan, O.; Artamonov, A.; Artoni, G.; Asai, S.; Asbah, N.; Ashkenazi, A.; Åsman, B.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Auerbach, B.; Augsten, K.; Aurousseau, M.; Avolio, G.; Axen, B.; Ayoub, M. K.; Azuelos, G.; Baak, M. A.; Baas, A. E.; Bacci, C.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Bain, T.; Baines, J. T.; Baker, O. K.; Balek, P.; Balestri, T.; Balli, F.; Banas, E.; Banerjee, Sw.; Bannoura, A. A. E.; Bansil, H. S.; Barak, L.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnes, S. L.; Barnett, B. M.; Barnett, R. M.; Barnovska, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Bartoldus, R.; Barton, A. E.; Bartos, P.; Bassalat, A.; Basye, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, M.; Bauer, F.; Bawa, H. S.; Beacham, J. B.; Beattie, M. D.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, S.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Behr, J. K.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Benary, O.; Benchekroun, D.; Bender, M.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez Garcia, J. A.; Benjamin, D. P.; Bensinger, J. R.; Bentvelsen, S.; Beresford, L.; Beretta, M.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Beringer, J.; Bernard, C.; Bernard, N. R.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertoli, G.; Bertolucci, F.; Bertsche, C.; Bertsche, D.; Besana, M. I.; Besjes, G. J.; Bessidskaia Bylund, O.; Bessner, M.; Besson, N.; Betancourt, C.; Bethke, S.; Bevan, A. J.; Bhimji, W.; Bianchi, R. M.; Bianchini, L.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Biglietti, M.; Bilbao De Mendizabal, J.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blanchard, J. -B.; Blanco, J. E.; Blazek, T.; Bloch, I.; Blocker, C.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Bock, C.; Boehler, M.; Bogaerts, J. A.; Bogdanchikov, A. G.; Bohm, C.; Boisvert, V.; Bold, T.; Boldea, V.; Boldyrev, A. S.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Borroni, S.; Bortfeldt, J.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Bousson, N.; Boutouil, S.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozic, I.; Bracinik, J.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brazzale, S. F.; Brendlinger, K.; Brennan, A. J.; Brenner, L.; Brenner, R.; Bressler, S.; Bristow, K.; Bristow, T. M.; Britton, D.; Britzger, D.; Brochu, F. M.; Brock, I.; Brock, R.; Bronner, J.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Brown, J.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Bruni, A.; Bruni, G.; Bruschi, M.; Bryngemark, L.; Buanes, T.; Buat, Q.; Buchholz, P.; Buckley, A. G.; Buda, S. I.; Budagov, I. A.; Buehrer, F.; Bugge, L.; Bugge, M. K.; Bulekov, O.; Burckhart, H.; Burdin, S.; Burghgrave, B.; Burke, S.; Burmeister, I.; Busato, E.; Büscher, D.; Büscher, V.; Bussey, P.; Buszello, C. P.; Butler, J. M.; Butt, A. I.; Buttar, C. M.; Butterworth, J. M.; Butti, P.; Buttinger, W.; Buzatu, A.; Cabrera Urbán, S.; Caforio, D.; Cakir, O.; Calafiura, P.; Calandri, A.; Calderini, G.; Calfayan, P.; Caloba, L. P.; Calvet, D.; Calvet, S.; Camacho Toro, R.; Camarda, S.; Cameron, D.; Caminada, L. M.; Caminal Armadans, R.; Campana, S.; Campanelli, M.; Campoverde, A.; Canale, V.; Canepa, A.; Cano Bret, M.; Cantero, J.; Cantrill, R.; Cao, T.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capua, M.; Caputo, R.; Cardarelli, R.; Carli, T.; Carlino, G.; Carminati, L.; Caron, S.; Carquin, E.; Carrillo-Montoya, G. D.; Carter, J. R.; Carvalho, J.; Casadei, D.; Casado, M. P.; Casolino, M.; Castaneda-Miranda, E.; Castelli, A.; Castillo Gimenez, V.; Castro, N. F.; Catastini, P.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Cattani, G.; Caudron, J.; Cavaliere, V.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Ceradini, F.; Cerio, B. C.; Cerny, K.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cerv, M.; Cervelli, A.; Cetin, S. A.; Chafaq, A.; Chakraborty, D.; Chalupkova, I.; Chang, P.; Chapleau, B.; Chapman, J. D.; Charfeddine, D.; Charlton, D. G.; Chau, C. C.; Chavez Barajas, C. A.; Cheatham, S.; Chegwidden, A.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, K.; Chen, L.; Chen, S.; Chen, X.; Chen, Y.; Cheng, H. C.; Cheng, Y.; Cheplakov, A.; Cheremushkina, E.; Cherkaoui El Moursli, R.; Chernyatin, V.; Cheu, E.; Chevalier, L.; Chiarella, V.; Childers, J. T.; Chilingarov, A.; Chiodini, G.; Chisholm, A. S.; Chislett, R. T.; Chitan, A.; Chizhov, M. V.; Choi, K.; Chouridou, S.; Chow, B. K. B.; Christodoulou, V.; Chromek-Burckhart, D.; Chu, M. L.; Chudoba, J.; Chuinard, A. J.; Chwastowski, J. J.; Chytka, L.; Ciapetti, G.; Ciftci, A. K.; Cinca, D.; Cindro, V.; Ciocio, A.; Citron, Z. H.; Ciubancan, M.; Clark, A.; Clark, P. J.; Clarke, R. N.; Cleland, W.; Clement, C.; Coadou, Y.; Cobal, M.; Coccaro, A.; Cochran, J.; Coffey, L.; Cogan, J. G.; Cole, B.; Cole, S.; Colijn, A. P.; Collot, J.; Colombo, T.; Compostella, G.; Conde Muiño, P.; Coniavitis, E.; Connell, S. H.; Connelly, I. A.; Consonni, S. M.; Consorti, V.; Constantinescu, S.; Conta, C.; Conti, G.; Conventi, F.; Cooke, M.; Cooper, B. D.; Cooper-Sarkar, A. M.; Copic, K.; Cornelissen, T.; Corradi, M.; Corriveau, F.; Corso-Radu, A.; Cortes-Gonzalez, A.; Cortiana, G.; Costa, G.; Costa, M. J.; Costanzo, D.; Côté, D.; Cottin, G.; Cowan, G.; Cox, B. E.; Cranmer, K.; Cree, G.; Crépé-Renaudin, S.; Crescioli, F.; Cribbs, W. A.; Crispin Ortuzar, M.; Cristinziani, M.; Croft, V.; Crosetti, G.; Cuhadar Donszelmann, T.; Cummings, J.; Curatolo, M.; Cuthbert, C.; Czirr, H.; Czodrowski, P.; D’Auria, S.; D’Onofrio, M.; Da Cunha Sargedas De Sousa, M. J.; Da Via, C.; Dabrowski, W.; Dafinca, A.; Dai, T.; Dale, O.; Dallaire, F.; Dallapiccola, C.; Dam, M.; Dandoy, J. R.; Daniells, A. C.; Danninger, M.; Dano Hoffmann, M.; Dao, V.; Darbo, G.; Darmora, S.; Dassoulas, J.; Dattagupta, A.; Davey, W.; David, C.; Davidek, T.; Davies, E.; Davies, M.; Davison, P.; Davygora, Y.; Dawe, E.; Dawson, I.; Daya-Ishmukhametova, R. K.; De, K.; de Asmundis, R.; De Castro, S.; De Cecco, S.; De Groot, N.; de Jong, P.; De la Torre, H.; De Lorenzi, F.; De Nooij, L.; De Pedis, D.; De Salvo, A.; De Sanctis, U.; De Santo, A.; De Vivie De Regie, J. B.; Dearnaley, W. J.; Debbe, R.; Debenedetti, C.; Dedovich, D. V.; Deigaard, I.; Del Peso, J.; Del Prete, T.; Delgove, D.; Deliot, F.; Delitzsch, C. M.; Deliyergiyev, M.; Dell’Acqua, A.; Dell’Asta, L.; Dell’Orso, M.; Della Pietra, M.; della Volpe, D.; Delmastro, M.; Delsart, P. A.; Deluca, C.; DeMarco, D. A.; Demers, S.; Demichev, M.; Demilly, A.; Denisov, S. P.; Derendarz, D.; Derkaoui, J. E.; Derue, F.; Dervan, P.; Desch, K.; Deterre, C.; Deviveiros, P. O.; Dewhurst, A.; Dhaliwal, S.; Di Ciaccio, A.; Di Ciaccio, L.; Di Domenico, A.; Di Donato, C.; Di Girolamo, A.; Di Girolamo, B.; Di Mattia, A.; Di Micco, B.; Di Nardo, R.; Di Simone, A.; Di Sipio, R.; Di Valentino, D.; Diaconu, C.; Diamond, M.; Dias, F. A.; Diaz, M. A.; Diehl, E. B.; Dietrich, J.; Diglio, S.; Dimitrievska, A.; Dingfelder, J.; Dita, P.; Dita, S.; Dittus, F.; Djama, F.; Djobava, T.; Djuvsland, J. I.; do Vale, M. A. B.; Dobos, D.; Dobre, M.; Doglioni, C.; Dohmae, T.; Dolejsi, J.; Dolezal, Z.; Dolgoshein, B. A.; Donadelli, M.; Donati, S.; Dondero, P.; Donini, J.; Dopke, J.; Doria, A.; Dova, M. T.; Doyle, A. T.; Drechsler, E.; Dris, M.; Dubreuil, E.; Duchovni, E.; Duckeck, G.; Ducu, O. A.; Duda, D.; Dudarev, A.; Duflot, L.; Duguid, L.; Dührssen, M.; Dunford, M.; Duran Yildiz, H.; Düren, M.; Durglishvili, A.; Duschinger, D.; Dwuznik, M.; Dyndal, M.; Ecker, K. M.; Edson, W.; Edwards, N. C.; Ehrenfeld, W.; Eifert, T.; Eigen, G.; Einsweiler, K.; Ekelof, T.; El Kacimi, M.; Ellert, M.; Elles, S.; Ellinghaus, F.; Elliot, A. A.; Ellis, N.; Elmsheuser, J.; Elsing, M.; Emeliyanov, D.; Enari, Y.; Endner, O. C.; Endo, M.; Erdmann, J.; Ereditato, A.; Eriksson, D.; Ernis, G.; Ernst, J.; Ernst, M.; Errede, S.; Ertel, E.; Escalier, M.; Esch, H.; Escobar, C.; Esposito, B.; Etienvre, A. I.; Etzion, E.; Evans, H.; Ezhilov, A.; Fabbri, L.; Facini, G.; Fakhrutdinov, R. M.; Falciano, S.; Falla, R. J.; Faltova, J.; Fang, Y.; Fanti, M.; Farbin, A.; Farilla, A.; Farooque, T.; Farrell, S.; Farrington, S. M.; Farthouat, P.; Fassi, F.; Fassnacht, P.; Fassouliotis, D.; Favareto, A.; Fayard, L.; Federic, P.; Fedin, O. L.; Fedorko, W.; Feigl, S.; Feligioni, L.; Feng, C.; Feng, E. J.; Feng, H.; Fenyuk, A. B.; Fernandez Martinez, P.; Fernandez Perez, S.; Ferrag, S.; Ferrando, J.; Ferrari, A.; Ferrari, P.; Ferrari, R.; Ferreira de Lima, D. E.; Ferrer, A.; Ferrere, D.; Ferretti, C.; Ferretto Parodi, A.; Fiascaris, M.; Fiedler, F.; Filipčič, A.; Filipuzzi, M.; Filthaut, F.; Fincke-Keeler, M.; Finelli, K. D.; Fiolhais, M. C. N.; Fiorini, L.; Firan, A.; Fischer, A.; Fischer, C.; Fischer, J.; Fisher, W. C.; Fitzgerald, E. A.; Flechl, M.; Fleck, I.; Fleischmann, P.; Fleischmann, S.; Fletcher, G. T.; Fletcher, G.; Flick, T.; Floderus, A.; Flores Castillo, L. R.; Flowerdew, M. J.; Formica, A.; Forti, A.; Fournier, D.; Fox, H.; Fracchia, S.; Francavilla, P.; Franchini, M.; Francis, D.; Franconi, L.; Franklin, M.; Fraternali, M.; Freeborn, D.; French, S. T.; Friedrich, F.; Froidevaux, D.; Frost, J. A.; Fukunaga, C.; Fullana Torregrosa, E.; Fulsom, B. G.; Fuster, J.; Gabaldon, C.; Gabizon, O.; Gabrielli, A.; Gabrielli, A.; Gadatsch, S.; Gadomski, S.; Gagliardi, G.; Gagnon, P.; Galea, C.; Galhardo, B.; Gallas, E. J.; Gallop, B. J.; Gallus, P.; Galster, G.; Gan, K. K.; Gao, J.; Gao, Y.; Gao, Y. S.; Garay Walls, F. M.; Garberson, F.; García, C.; García Navarro, J. E.; Garcia-Sciveres, M.; Gardner, R. W.; Garelli, N.; Garonne, V.; Gatti, C.; Gaudio, G.; Gaur, B.; Gauthier, L.; Gauzzi, P.; Gavrilenko, I. L.; Gay, C.; Gaycken, G.; Gazis, E. N.; Ge, P.; Gecse, Z.; Gee, C. N. P.; Geerts, D. A. A.; Geich-Gimbel, Ch.; Gemme, C.; Genest, M. H.; Gentile, S.; George, M.; George, S.; Gerbaudo, D.; Gershon, A.; Ghazlane, H.; Ghodbane, N.; Giacobbe, B.; Giagu, S.; Giangiobbe, V.; Giannetti, P.; Gianotti, F.; Gibbard, B.; Gibson, S. M.; Gilchriese, M.; Gillam, T. P. S.; Gillberg, D.; Gilles, G.; Gingrich, D. M.; Giokaris, N.; Giordani, M. P.; Giorgi, F. M.; Giorgi, F. M.; Giraud, P. F.; Giromini, P.; Giugni, D.; Giuliani, C.; Giulini, M.; Gjelsten, B. K.; Gkaitatzis, S.; Gkialas, I.; Gkougkousis, E. L.; Gladilin, L. K.; Glasman, C.; Glatzer, J.; Glaysher, P. C. F.; Glazov, A.; Goblirsch-Kolb, M.; Goddard, J. R.; Godlewski, J.; Goldfarb, S.; Golling, T.; Golubkov, D.; Gomes, A.; Gonçalo, R.; Goncalves Pinto Firmino Da Costa, J.; Gonella, L.; González de la Hoz, S.; Gonzalez Parra, G.; Gonzalez-Sevilla, S.; Goossens, L.; Gorbounov, P. A.; Gordon, H. A.; Gorelov, I.; Gorini, B.; Gorini, E.; Gorišek, A.; Gornicki, E.; Goshaw, A. T.; Gössling, C.; Gostkin, M. I.; Gouighri, M.; Goujdami, D.; Goussiou, A. G.; Grabas, H. M. X.; Graber, L.; Grabowska-Bold, I.; Grafström, P.; Grahn, K-J.; Gramling, J.; Gramstad, E.; Grancagnolo, S.; Grassi, V.; Gratchev, V.; Gray, H. M.; Graziani, E.; Greenwood, Z. D.; Gregersen, K.; Gregor, I. M.; Grenier, P.; Griffiths, J.; Grillo, A. A.; Grimm, K.; Grinstein, S.; Gris, Ph.; Grivaz, J. -F.; Grohs, J. P.; Grohsjean, A.; Gross, E.; Grosse-Knetter, J.; Grossi, G. C.; Grout, Z. J.; Guan, L.; Guenther, J.; Guescini, F.; Guest, D.; Gueta, O.; Guido, E.; Guillemin, T.; Guindon, S.; Gul, U.; Gumpert, C.; Guo, J.; Gupta, S.; Gutierrez, P.; Gutierrez Ortiz, N. G.; Gutschow, C.; Guttman, N.; Guyot, C.; Gwenlan, C.; Gwilliam, C. B.; Haas, A.; Haber, C.; Hadavand, H. K.; Haddad, N.; Haefner, P.; Hageböck, S.; Hajduk, Z.; Hakobyan, H.; Haleem, M.; Haley, J.; Hall, D.; Halladjian, G.; Hallewell, G. D.; Hamacher, K.; Hamal, P.; Hamano, K.; Hamer, M.; Hamilton, A.; Hamilton, S.; Hamity, G. N.; Hamnett, P. G.; Han, L.; Hanagaki, K.; Hanawa, K.; Hance, M.; Hanke, P.; Hanna, R.; Hansen, J. B.; Hansen, J. D.; Hansen, P. H.; Hara, K.; Hard, A. S.; Harenberg, T.; Hariri, F.; Harkusha, S.; Harrington, R. D.; Harrison, P. F.; Hartjes, F.; Hasegawa, M.; Hasegawa, S.; Hasegawa, Y.; Hasib, A.; Hassani, S.; Haug, S.; Hauser, R.; Hauswald, L.; Havranek, M.; Hawkes, C. M.; Hawkings, R. J.; Hawkins, A. D.; Hayashi, T.; Hayden, D.; Hays, C. P.; Hays, J. M.; Hayward, H. S.; Haywood, S. J.; Head, S. J.; Heck, T.; Hedberg, V.; Heelan, L.; Heim, S.; Heim, T.; Heinemann, B.; Heinrich, L.; Hejbal, J.; Helary, L.; Heller, M.; Hellman, S.; Hellmich, D.; Helsens, C.; Henderson, J.; Henderson, R. C. W.; Heng, Y.; Hengler, C.; Henrichs, A.; Henriques Correia, A. M.; Henrot-Versille, S.; Herbert, G. H.; Hernández Jiménez, Y.; Herrberg-Schubert, R.; Herten, G.; Hertenberger, R.; Hervas, L.; Hesketh, G. G.; Hessey, N. P.; Hetherly, J. W.; Hickling, R.; Higón-Rodriguez, E.; Hill, E.; Hill, J. C.; Hiller, K. H.; Hillier, S. J.; Hinchliffe, I.; Hines, E.; Hinman, R. R.; Hirose, M.; Hirschbuehl, D.; Hobbs, J.; Hod, N.; Hodgkinson, M. C.; Hodgson, P.; Hoecker, A.; Hoeferkamp, M. R.; Hoenig, F.; Hohlfeld, M.; Hohn, D.; Holmes, T. R.; Hong, T. M.; Hooft van Huysduynen, L.; Hopkins, W. H.; Horii, Y.; Horton, A. J.; Hostachy, J-Y.; Hou, S.; Hoummada, A.; Howard, J.; Howarth, J.; Hrabovsky, M.; Hristova, I.; Hrivnac, J.; Hryn’ova, T.; Hrynevich, A.; Hsu, C.; Hsu, P. J.; Hsu, S. -C.; Hu, D.; Hu, Q.; Hu, X.; Huang, Y.; Hubacek, Z.; Hubaut, F.; Huegging, F.; Huffman, T. B.; Hughes, E. W.; Hughes, G.; Huhtinen, M.; Hülsing, T. A.; Huseynov, N.; Huston, J.; Huth, J.; Iacobucci, G.; Iakovidis, G.; Ibragimov, I.; Iconomidou-Fayard, L.; Ideal, E.; Idrissi, Z.; Iengo, P.; Igonkina, O.; Iizawa, T.; Ikegami, Y.; Ikematsu, K.; Ikeno, M.; Ilchenko, Y.; Iliadis, D.; Ilic, N.; Inamaru, Y.; Ince, T.; Ioannou, P.; Iodice, M.; Iordanidou, K.; Ippolito, V.; Irles Quiles, A.; Isaksson, C.; Ishino, M.; Ishitsuka, M.; Ishmukhametov, R.; Issever, C.; Istin, S.; Iturbe Ponce, J. M.; Iuppa, R.; Ivarsson, J.; Iwanski, W.; Iwasaki, H.; Izen, J. M.; Izzo, V.; Jabbar, S.; Jackson, B.; Jackson, M.; Jackson, P.; Jaekel, M. R.; Jain, V.; Jakobs, K.; Jakobsen, S.; Jakoubek, T.; Jakubek, J.; Jamin, D. O.; Jana, D. K.; Jansen, E.; Jansky, R. W.; Janssen, J.; Janus, M.; Jarlskog, G.; Javadov, N.; Javůrek, T.; Jeanty, L.; Jejelava, J.; Jeng, G. -Y.; Jennens, D.; Jenni, P.; Jentzsch, J.; Jeske, C.; Jézéquel, S.; Ji, H.; Jia, J.; Jiang, Y.; Jiggins, S.; Jimenez Pena, J.; Jin, S.; Jinaru, A.; Jinnouchi, O.; Joergensen, M. D.; Johansson, P.; Johns, K. A.; Jon-And, K.; Jones, G.; Jones, R. W. L.; Jones, T. J.; Jongmanns, J.; Jorge, P. M.; Joshi, K. D.; Jovicevic, J.; Ju, X.; Jung, C. A.; Jussel, P.; Juste Rozas, A.; Kaci, M.; Kaczmarska, A.; Kado, M.; Kagan, H.; Kagan, M.; Kahn, S. J.; Kajomovitz, E.; Kalderon, C. W.; Kama, S.; Kamenshchikov, A.; Kanaya, N.; Kaneda, M.; Kaneti, S.; Kantserov, V. A.; Kanzaki, J.; Kaplan, B.; Kapliy, A.; Kar, D.; Karakostas, K.; Karamaoun, A.; Karastathis, N.; Kareem, M. J.; Karnevskiy, M.; Karpov, S. N.; Karpova, Z. M.; Karthik, K.; Kartvelishvili, V.; Karyukhin, A. N.; Kashif, L.; Kass, R. D.; Kastanas, A.; Kataoka, Y.; Katre, A.; Katzy, J.; Kawagoe, K.; Kawamoto, T.; Kawamura, G.; Kazama, S.; Kazanin, V. F.; Kazarinov, M. Y.; Keeler, R.; Kehoe, R.; Keller, J. S.; Kempster, J. J.; Keoshkerian, H.; Kepka, O.; Kerševan, B. P.; Kersten, S.; Keyes, R. A.; Khalil-zada, F.; Khandanyan, H.; Khanov, A.; Kharlamov, A. G.; Khodinov, A.; Khoo, T. J.; Khovanskiy, V.; Khramov, E.; Khubua, J.; Kim, H. Y.; Kim, H.; Kim, S. H.; Kim, Y.; Kimura, N.; Kind, O. M.; King, B. T.; King, M.; King, R. S. B.; King, S. B.; Kirk, J.; Kiryunin, A. E.; Kishimoto, T.; Kisielewska, D.; Kiss, F.; Kiuchi, K.; Kivernyk, O.; Kladiva, E.; Klein, M. H.; Klein, M.; Klein, U.; Kleinknecht, K.; Klimek, P.; Klimentov, A.; Klingenberg, R.; Klinger, J. A.; Klioutchnikova, T.; Klok, P. F.; Kluge, E. -E.; Kluit, P.; Kluth, S.; Kneringer, E.; Knoops, E. B. F. G.; Knue, A.; Kobayashi, D.; Kobayashi, T.; Kobel, M.; Kocian, M.; Kodys, P.; Koffas, T.; Koffeman, E.; Kogan, L. 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B.; Simak, V.; Simard, O.; Simic, Lj.; Simion, S.; Simioni, E.; Simmons, B.; Simon, D.; Simoniello, R.; Sinervo, P.; Sinev, N. B.; Siragusa, G.; Sisakyan, A. N.; Sivoklokov, S. Yu.; Sjölin, J.; Sjursen, T. B.; Skinner, M. B.; Skottowe, H. P.; Skubic, P.; Slater, M.; Slavicek, T.; Slawinska, M.; Sliwa, K.; Smakhtin, V.; Smart, B. H.; Smestad, L.; Smirnov, S. Yu.; Smirnov, Y.; Smirnova, L. N.; Smirnova, O.; Smith, M. N. K.; Smizanska, M.; Smolek, K.; Snesarev, A. A.; Snidero, G.; Snyder, S.; Sobie, R.; Socher, F.; Soffer, A.; Soh, D. A.; Solans, C. A.; Solar, M.; Solc, J.; Soldatov, E. Yu.; Soldevila, U.; Solodkov, A. A.; Soloshenko, A.; Solovyanov, O. V.; Solovyev, V.; Sommer, P.; Song, H. Y.; Soni, N.; Sood, A.; Sopczak, A.; Sopko, B.; Sopko, V.; Sorin, V.; Sosa, D.; Sosebee, M.; Sotiropoulou, C. L.; Soualah, R.; Soueid, P.; Soukharev, A. M.; South, D.; Spagnolo, S.; Spalla, M.; Spanò, F.; Spearman, W. R.; Spettel, F.; Spighi, R.; Spigo, G.; Spiller, L. A.; Spousta, M.; Spreitzer, T.; St. Denis, R. D.; Staerz, S.; Stahlman, J.; Stamen, R.; Stamm, S.; Stanecka, E.; Stanescu, C.; Stanescu-Bellu, M.; Stanitzki, M. M.; Stapnes, S.; Starchenko, E. A.; Stark, J.; Staroba, P.; Starovoitov, P.; Staszewski, R.; Stavina, P.; Steinberg, P.; Stelzer, B.; Stelzer, H. J.; Stelzer-Chilton, O.; Stenzel, H.; Stern, S.; Stewart, G. A.; Stillings, J. A.; Stockton, M. C.; Stoebe, M.; Stoicea, G.; Stolte, P.; Stonjek, S.; Stradling, A. R.; Straessner, A.; Stramaglia, M. E.; Strandberg, J.; Strandberg, S.; Strandlie, A.; Strauss, E.; Strauss, M.; Strizenec, P.; Ströhmer, R.; Strom, D. M.; Stroynowski, R.; Strubig, A.; Stucci, S. A.; Stugu, B.; Styles, N. A.; Su, D.; Su, J.; Subramaniam, R.; Succurro, A.; Sugaya, Y.; Suhr, C.; Suk, M.; Sulin, V. V.; Sultansoy, S.; Sumida, T.; Sun, S.; Sun, X.; Sundermann, J. E.; Suruliz, K.; Susinno, G.; Sutton, M. R.; Suzuki, Y.; Svatos, M.; Swedish, S.; Swiatlowski, M.; Sykora, I.; Sykora, T.; Ta, D.; Taccini, C.; Tackmann, K.; Taenzer, J.; Taffard, A.; Tafirout, R.; Taiblum, N.; Takai, H.; Takashima, R.; Takeda, H.; Takeshita, T.; Takubo, Y.; Talby, M.; Talyshev, A. A.; Tam, J. Y. C.; Tan, K. G.; Tanaka, J.; Tanaka, R.; Tanaka, S.; Tanaka, S.; Tanasijczuk, A. J.; Tannenwald, B. B.; Tannoury, N.; Tapprogge, S.; Tarem, S.; Tarrade, F.; Tartarelli, G. F.; Tas, P.; Tasevsky, M.; Tashiro, T.; Tassi, E.; Tavares Delgado, A.; Tayalati, Y.; Taylor, F. E.; Taylor, G. N.; Taylor, W.; Teischinger, F. A.; Teixeira Dias Castanheira, M.; Teixeira-Dias, P.; Temming, K. K.; Ten Kate, H.; Teng, P. K.; Teoh, J. J.; Tepel, F.; Terada, S.; Terashi, K.; Terron, J.; Terzo, S.; Testa, M.; Teuscher, R. J.; Therhaag, J.; Theveneaux-Pelzer, T.; Thomas, J. P.; Thomas-Wilsker, J.; Thompson, E. N.; Thompson, P. D.; Thompson, R. J.; Thompson, A. S.; Thomsen, L. A.; Thomson, E.; Thomson, M.; Thun, R. P.; Tian, F.; Tibbetts, M. J.; Ticse Torres, R. E.; Tikhomirov, V. O.; Tikhonov, Yu. A.; Timoshenko, S.; Tiouchichine, E.; Tipton, P.; Tisserant, S.; Todorov, T.; Todorova-Nova, S.; Tojo, J.; Tokár, S.; Tokushuku, K.; Tollefson, K.; Tolley, E.; Tomlinson, L.; Tomoto, M.; Tompkins, L.; Toms, K.; Torrence, E.; Torres, H.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Tran, H. L.; Trefzger, T.; Tremblet, L.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Tripiana, M. F.; Trischuk, W.; Trocmé, B.; Troncon, C.; Trottier-McDonald, M.; Trovatelli, M.; True, P.; Trzebinski, M.; Trzupek, A.; Tsarouchas, C.; Tseng, J. C-L.; Tsiareshka, P. V.; Tsionou, D.; Tsipolitis, G.; Tsirintanis, N.; Tsiskaridze, S.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsukerman, I. I.; Tsulaia, V.; Tsuno, S.; Tsybychev, D.; Tudorache, A.; Tudorache, V.; Tuna, A. N.; Tupputi, S. A.; Turchikhin, S.; Turecek, D.; Turra, R.; Turvey, A. J.; Tuts, P. M.; Tykhonov, A.; Tylmad, M.; Tyndel, M.; Ueda, I.; Ueno, R.; Ughetto, M.; Ugland, M.; Uhlenbrock, M.; Ukegawa, F.; Unal, G.; Undrus, A.; Unel, G.; Ungaro, F. C.; Unno, Y.; Unverdorben, C.; Urban, J.; Urquijo, P.; Urrejola, P.; Usai, G.; Usanova, A.; Vacavant, L.; Vacek, V.; Vachon, B.; Valderanis, C.; Valencic, N.; Valentinetti, S.; Valero, A.; Valery, L.; Valkar, S.; Valladolid Gallego, E.; Vallecorsa, S.; Valls Ferrer, J. A.; Van Den Wollenberg, W.; Van Der Deijl, P. C.; van der Geer, R.; van der Graaf, H.; Van Der Leeuw, R.; van Eldik, N.; van Gemmeren, P.; Van Nieuwkoop, J.; van Vulpen, I.; van Woerden, M. C.; Vanadia, M.; Vandelli, W.; Vanguri, R.; Vaniachine, A.; Vannucci, F.; Vardanyan, G.; Vari, R.; Varnes, E. W.; Varol, T.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vazeille, F.; Vazquez Schroeder, T.; Veatch, J.; Veloso, F.; Velz, T.; Veneziano, S.; Ventura, A.; Ventura, D.; Venturi, M.; Venturi, N.; Venturini, A.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, J. C.; Vest, A.; Vetterli, M. C.; Viazlo, O.; Vichou, I.; Vickey, T.; Vickey Boeriu, O. E.; Viehhauser, G. H. A.; Viel, S.; Vigne, R.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Vivarelli, I.; Vives Vaque, F.; Vlachos, S.; Vladoiu, D.; Vlasak, M.; Vogel, M.; Vokac, P.; Volpi, G.; Volpi, M.; von der Schmitt, H.; von Radziewski, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vuillermet, R.; Vukotic, I.; Vykydal, Z.; Wagner, P.; Wagner, W.; Wahlberg, H.; Wahrmund, S.; Wakabayashi, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, K.; Wang, R.; Wang, S. M.; Wang, T.; Wang, X.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Warsinsky, M.; Washbrook, A.; Wasicki, C.; Watkins, P. M.; Watson, A. T.; Watson, I. J.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, S.; Weber, M. S.; Weber, S. W.; Webster, J. S.; Weidberg, A. R.; Weinert, B.; Weingarten, J.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wendland, D.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M.; Werner, P.; Wessels, M.; Wetter, J.; Whalen, K.; Wharton, A. M.; White, A.; White, M. J.; White, R.; White, S.; Whiteson, D.; Wicke, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wienemann, P.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wildauer, A.; Wilkens, H. G.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, A.; Wilson, J. A.; Wingerter-Seez, I.; Winklmeier, F.; Winter, B. T.; Wittgen, M.; Wittkowski, J.; Wollstadt, S. J.; Wolter, M. W.; Wolters, H.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wozniak, K. W.; Wu, M.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xu, D.; Xu, L.; Yabsley, B.; Yacoob, S.; Yakabe, R.; Yamada, M.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, S.; Yamanaka, T.; Yamauchi, K.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, Y.; Yao, L.; Yao, W-M.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yeletskikh, I.; Yen, A. L.; Yildirim, E.; Yorita, K.; Yoshida, R.; Yoshihara, K.; Young, C.; Young, C. J. S.; Youssef, S.; Yu, D. R.; Yu, J.; Yu, J. M.; Yu, J.; Yuan, L.; Yurkewicz, A.; Yusuff, I.; Zabinski, B.; Zaidan, R.; Zaitsev, A. M.; Zalieckas, J.; Zaman, A.; Zambito, S.; Zanello, L.; Zanzi, D.; Zeitnitz, C.; Zeman, M.; Zemla, A.; Zengel, K.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zhang, D.; Zhang, F.; Zhang, J.; Zhang, L.; Zhang, R.; Zhang, X.; Zhang, Z.; Zhao, X.; Zhao, Y.; Zhao, Z.; Zhemchugov, A.; Zhong, J.; Zhou, B.; Zhou, C.; Zhou, L.; Zhou, L.; Zhou, N.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhukov, K.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, R.; Zimmermann, S.; Zinonos, Z.; Zinser, M.; Ziolkowski, M.; Živković, L.; Zobernig, G.; Zoccoli, A.; zur Nedden, M.; Zurzolo, G.; Zwalinski, L.

    2015-10-19

    In this study, the normalized differential cross section for top-quark pair production in association with at least one jet is studied as a function of the inverse of the invariant mass of the tt¯ + 1-jet system. This distribution can be used for a precise determination of the top-quark mass since gluon radiation depends on the mass of the quarks. The experimental analysis is based on proton-proton collision data collected by the ATLAS detector at the LHC with a centre-of-mass energy of 7 TeV corresponding to an integrated luminosity of 4.6 fb–1 . The selected events were identified using the lepton+jets top-quark-pair decay channel, where lepton refers to either an electron or a muon. The observed distribution is compared to a theoretical prediction at next-to-leading-order accuracy in quantum chromodynamics using the pole-mass scheme. With this method, the measured value of the top-quark pole mass, mpolet , is: mpolet = 173.7 ± 1.5(stat.) ± 1.4(syst.)+1.0–0.5(theory) GeV.

  2. Λb→pl⁻ν¯l form factors from lattice QCD with static b quarks

    SciTech Connect (OSTI)

    Detmold, William; Lin, C.-J. David; Meinel, Stefan; Wingate, Matthew

    2013-07-23

    We present a lattice QCD calculation of form factors for the decay Λb→pμ⁻ν¯μ, which is a promising channel for determining the Cabibbo-Kobayashi-Maskawa matrix element |Vub| at the Large Hadron Collider. In this initial study we work in the limit of static b quarks, where the number of independent form factors reduces to two. We use dynamical domain-wall fermions for the light quarks, and perform the calculation at two different lattice spacings and at multiple values of the light-quark masses in a single large volume. Using our form factor results, we calculate the Λb→pμ⁻ν¯μ differential decay rate in the range 14 GeV²≤q²≤q²max, and obtain the integral ∫max 14 GeV²[dΓ/dq²]dq²/|Vub|²=15.3±4.2 ps⁻¹. Combined with future experimental data, this will give a novel determination of |Vub| with about 15% theoretical uncertainty. The uncertainty is dominated by the use of the static approximation for the b quark, and can be reduced further by performing the lattice calculation with a more sophisticated heavy-quark action.

  3. Search for single top quark production in pbar p collisions at sqrt{s}=1.96 TeV in the missing transverse energy plus jets topology

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.; Apresyan, A.; /Purdue U. /Waseda U.

    2010-01-01

    We report a search for single top quark production with the CDF II detector using 2.1 fb{sup -1} of integrated luminosity of p{bar p} collisions at {radical}s = 1.96 TeV. The data selected consist of events characterized by large energy imbalance in the transverse plane and hadronic jets, and no identified electrons and muons, so the sample is enriched in W {yields} {tau}{nu} decays. In order to suppress backgrounds, additional kinematic and topological requirements are imposed through a neural network, and at least one of the jets must be identified as a b quark jet. We measure an excess of signal-like events in agreement with the standard model prediction, but inconsistent with a model without single top quark production by 2.1 standard deviations ({sigma}), with a median expected sensitivity of 1.4 {sigma}. Assuming a top quark mass of 175 GeV/c{sup 2} and ascribing the excess to single top quark production, the cross section is measured to be 4.9{sub -2.2}{sup +2.5} (stat+syst) pb, consistent with measurements performed in independent datasets and with the standard model prediction.

  4. High Q{sup 2} behavior of the electromagnetic form factors in the relativistic hypercentral constituent quark model

    SciTech Connect (OSTI)

    Santopinto, E.; Vassallo, A.; Giannini, M. M.; De Sanctis, M.

    2010-12-15

    The ratio R{sub p} between the electric and magnetic proton form factors has been recently measured at Jefferson Lab up to Q{sup 2}=8.5 GeV{sup 2}. We have extended the calculation of the nucleon form factors with the hypercentral constituent quark model and compared them with the data on R{sub p} and on the Q{sup 2} behavior of the ratio Q{sup 2}F{sub 2}/F{sub 1}. In both cases, the theoretical curves agree with the experimental points.

  5. Measurement of the differential cross section for top quark pair production in pp collisions at $$\\sqrt{s}$$ = 8 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2015-11-20

    The normalized differential cross section for top quark pair (tt¯) production is measured in pp collisions at a centre-of-mass energy of 8TeV at the CERN LHC using the CMS detector in data corresponding to an integrated luminosity of 19.7fb–1. The measurements are performed in the lepton+jets (e/μ +jets) and in the dilepton (e+e–, μ+μ–, and e±μ∓) decay channels. The tt¯ cross section is measured as a function of the kinematic properties of the charged leptons, the jets associated to b quarks, the top quarks, and the tt¯ system. The data are compared with several predictions from perturbative quantum chromodynamic upmore » to approximate next-to-next-to-leading-order precision. Furthermore, no significant deviations are observed relative to the standard model predictions.« less

  6. Measurements of spin correlation in top-antitop quark events from proton-proton collisions at s=7  TeV using the ATLAS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; et al

    2014-12-24

    We present measurements of spin correlation in top quark pair production using data collected with the ATLAS detector at the LHC with proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 4.6 fb₋1. Events are selected in final states with two charged leptons and at least two jets and in final states with one charged lepton and at least four jets. Four different observables sensitive to different properties of the top quark pair production mechanism are used to extract the correlation between the top and antitop quark spins. Some of these observables are measuredmore » for the first time. The measurements are in good agreement with the Standard Model prediction at next-to-leading-order accuracy.« less

  7. Measurements of spin correlation in top-antitop quark events from proton-proton collisions ats=7  TeVusing the ATLAS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; et al

    2014-12-24

    Measurements of spin correlation in top quark pair production are presented using data collected with the ATLAS detector at the LHC with proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 4.6  fb⁻¹. Events are selected in final states with two charged leptons and at least two jets and in final states with one charged lepton and at least four jets. Four different observables sensitive to different properties of the top quark pair production mechanism are used to extract the correlation between the top and antitop quark spins. Some of these observables are measured formore » the first time. The measurements are in good agreement with the Standard Model prediction at next-to-leading-order accuracy.« less

  8. Measurement of the charge asymmetry in top quark pair production in pp collisions at $\\sqrt{s}$ = 8 TeV using a template method

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-08-18

    The charge asymmetry in the production of top quark and antiquark pairs is measured in proton-proton collisions at a center-of-mass energy of 8 TeV. The data, corresponding to an integrated luminosity of 19.6 fb -1 were collected by the CMS experiment at the LHC. Events with a single isolated electron or muon, and four or more jets, at least one of which is likely to have originated from hadronization of a bottom quark, are selected. A template technique is used to measure the asymmetry in the distribution of differences in the top quark and antiquark absolute rapidities. The measured asymmetry is Ayc= [0.33_0.26 (stat)_0.33 (syst)]%, which is the most precise result to date. The results are compared to calculations based on the standard model and on several beyond-the-standard-model scenarios.

  9. Measurement of Dijet Angular Distributions and Search for Quark Compositeness in pp Collisions at $sqrt{s} = 7$ TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan; et al.

    2011-05-01

    Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at s? = 7 TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36 inverse picobarns. The data are found to be in good agreement with the predictions of perturbative QCD, and yield no evidence of quark compositeness. With a modified frequentist approach, a lower limit on the contact interaction scale for left-handed quarks of Lambda = 5.6 TeV is obtained at the 95% confidence level.

  10. Study of Polarized Sea Quark Distributions in Polarized Proton-Proton Collisions at sq root(s) = 500 GeV with PHENIX

    SciTech Connect (OSTI)

    Mibe, Tsutomu

    2009-08-04

    The PHENIX spin program studies the flavor structure of the polarized sea quark distributions in polarized proton-proton collisions. Starting from 2009 run, the quark and antiquark polarization, sorted by flavor, will be investigated with the parity-violating single-spin asymmetry of W-boson production at the collision energy of sq root(s) = 500 GeV. High momentum muons from W-boson decay are detected in the PHENIX muon arms. The muon trigger is being upgraded to allow one to select high momentum muons.

  11. Search for neutral Higgs bosons decaying to tau pairs produced in association with b-quarks at s**(1/2)=1.96 TeV

    SciTech Connect (OSTI)

    Herner, Kenneth Richard; /SUNY, Stony Brook

    2008-12-01

    We report results from a search for neutral Higgs bosons decaying to tau pairs produced in association with a b-quark in 1.6 fb{sup -1} of data taken from June 2006 to March 2008 with the D0 detector at Fermi National Accelerator Laboratory. The final state includes a muon, hadronically decaying tau, and jet identified as coming from a b-quark. We set cross section times branching ratio limits on production of such neutral Higgs bosons {phi} in the mass range from 90 GeV to 160 GeV. Exclusion limits are set at the 95% Confidence Level for several supersymmetric scenarios.

  12. Top Quark Produced Through the Electroweak Force: Discovery Using the Matrix Element Analysis and Search for Heavy Gauge Bosons Using Boosted Decision Trees

    SciTech Connect (OSTI)

    Pangilinan, Monica; /Brown U.

    2010-02-01

    The top quark produced through the electroweak channel provides a direct measurement of the V{sub tb} element in the CKM matrix which can be viewed as a transition rate of a top quark to a bottom quark. This production channel of top quark is also sensitive to different theories beyond the Standard Model such as heavy charged gauged bosons termed W{prime}. This thesis measures the cross section of the electroweak produced top quark using a technique based on using the matrix elements of the processes under consideration. The technique is applied to 2.3 fb{sup -1} of data from the D0 detector. From a comparison of the matrix element discriminants between data and the signal and background model using Bayesian statistics, we measure the cross section of the top quark produced through the electroweak mechanism {sigma}(p{bar p} {yields} tb + X, tqb + X) = 4.30{sub -1.20}{sup +0.98} pb. The measured result corresponds to a 4.9{sigma} Gaussian-equivalent significance. By combining this analysis with other analyses based on the Bayesian Neural Network (BNN) and Boosted Decision Tree (BDT) method, the measured cross section is 3.94 {+-} 0.88 pb with a significance of 5.0{sigma}, resulting in the discovery of electroweak produced top quarks. Using this measured cross section and constraining |V{sub tb}| < 1, the 95% confidence level (C.L.) lower limit is |V{sub tb}| > 0.78. Additionally, a search is made for the production of W{prime} using the same samples from the electroweak produced top quark. An analysis based on the BDT method is used to separate the signal from expected backgrounds. No significant excess is found and 95% C.L. upper limits on the production cross section are set for W{prime} with masses within 600-950 GeV. For four general models of W{prime} boson production using decay channel W{prime} {yields} t{bar b}, the lower mass limits are the following: M(W{prime}{sub L} with SM couplings) > 840 GeV; M(W{prime}{sub R}) > 880 GeV or 890 GeV if the right-handed neutrino is lighter or heavier than W{prime}{sub R}; and M(W{prime}{sub L+R}) > 915 GeV.

  13. The Secret Life of Quarks, Final Report for the University of North Carolina at Chapel Hill

    SciTech Connect (OSTI)

    Fowler, Robert

    2012-12-10

    This final report summarizes activities and results at the University of North Carolina as part of the the SciDAC-2 Project The Secret Life of Quarks: National Computational Infrastructure for Lattice Quantum Chromodynamics. The overall objective of the project is to construct the software needed to study quantum chromo- dynamics (QCD), the theory of the strong interactions of subatomic physics, and similar strongly coupled gauge theories anticipated to be of importance in the LHC era. It built upon the successful efforts of the SciDAC-1 project National Computational Infrastructure for Lattice Gauge Theory, in which a QCD Applications Programming Interface (QCD API) was developed that enables lat- tice gauge theorists to make effective use of a wide variety of massively parallel computers. In the SciDAC-2 project, optimized versions of the QCD API were being created for the IBM Blue- Gene/L (BG/L) and BlueGene/P (BG/P), the Cray XT3/XT4 and its successors, and clusters based on multi-core processors and Infiniband communications networks. The QCD API is being used to enhance the performance of the major QCD community codes and to create new applications. Software libraries of physics tools have been expanded to contain sharable building blocks for inclusion in application codes, performance analysis and visualization tools, and software for au- tomation of physics work flow. New software tools were designed for managing the large data sets generated in lattice QCD simulations, and for sharing them through the International Lattice Data Grid consortium. As part of the overall project, researchers at UNC were funded through ASCR to work in three general areas. The main thrust has been performance instrumentation and analysis in support of the SciDAC QCD code base as it evolved and as it moved to new computation platforms. In support of the performance activities, performance data was to be collected in a database for the purpose of broader analysis. Third, the UNC work was done at RENCI (Renaissance Computing Institute), which has extensive expertise and facilities for scientific data visualization, so we acted in an ongoing consulting and support role in that area.

  14. Forward-Backward Asymmetry of Top Quark Pair Productionn at the Fermilab Tevatron

    SciTech Connect (OSTI)

    Hong, Ziqing

    2015-12-01

    This dissertation presents the final measurements of the forward--backward asymmetry ($A_{\\text{FB}}$) of top quark--antiquark pair events ($t\\bar{t}$) at the Collider Detector at Fermilab (CDF) experiment. The $t\\bar{t}$ events are produced in proton--anti-proton collisions with a center of mass energy of $1.96~\\mathrm{TeV}$ during the Run II of the Fermilab Tevatron. The measurements are performed with the full CDF Run II data ($9.1~\\mathrm{fb}^{-1}$) in the final state that contain two charged leptons (electrons or muons, the dilepton final state), and are designed to confirm or deny the evidence-level excess in the $A_{\\text{FB}}$ measurements in the final state with a single lepton and hadronic jets (lepton+jets final state) as well as the excess in the preliminary measurements in the dilepton final state with the first half of the CDF Run II data. New measurements include the leptonic $A_{\\text{FB}}$ ($A_{\\text{FB}}^{\\ell}$), the lepton-pair $A_{\\text{FB}}$ ($A_{\\text{FB}}^{\\ell\\ell}$) and the reconstructed top $A_{\\text{FB}}$ ($A_{\\text{FB}}^{t\\bar{t}}$). Each are combined with the previous results from the lepton+jets final state measured at the CDF experiment. The inclusive $A_{\\text{FB}}^{\\ell}$, $A_{\\text{FB}}^{\\ell\\ell}$, and $A_{\\text{FB}}^{t\\bar{t}}$ measured in the dilepton final state are $0.072\\pm0.060$, $0.076\\pm0.081$, and $0.12 \\pm 0.13$, to be compared with the Standard Model (SM) predictions of $0.038\\pm0.003$, $0.048\\pm0.004$, and $0.010\\pm0.006$, respectively. The CDF combination of $A_{\\text{FB}}^{\\ell}$ and $A_{\\text{FB}}^{t\\bar{t}}$ are $0.090^{+0.028}_{-0.026}$, and $0.160\\pm0.045$, respectively. The overall results are consistent with the SM predictions.

  15. SYSTEMATIC STUDIES OF HEAVY ION COLLISIONS TO SEARCH FOR QUARK-GLUON PLASMA

    SciTech Connect (OSTI)

    Fuqiang Wang

    2007-11-29

    This is the final technical report for DOE Outstanding Junior Investigator (OJI) Award, 'Systematic Studies of Heavy Ion Collisions to Search for Quark-Gluon Plasma', grant DE-FG02-02ER41219, Principal Investigator (PI) Fuqiang Wang. The research under the grant was divided into two phases. The first concentrated on systematic studies of soft hadron production at low transverse momentum (p{sub T}), in particular the production of (anti-)baryon and strangeness in heavy ion collisions at RHIC energies. The second concentrated on measurements of di-hadron and multi-hadron jet-correlations and investigations of medium response to jets. The research was conducted at the Relativistic Heavy-Ion Collider (RHIC) at BNL with the Solenoidal Tracker At RHIC (STAR) experiment. The total grant is $214,000. The grant established a PC farm solely used for this research. The PC farm consists of 8 nodes with a total of 16 CPUs and 3 disk servers of total 2 TB shared storage. The current balance of the grant is $19,985. The positive balance is because an initial purchase of $22,600 for the PC farm came out of the PI's start-up fund due to the lateness of the award. The PC farm is an integral part of the Purdue Physics Department's computer cluster. The grant supported two Ph.D. graduate students. Levente Molnar was supported from July 2002 to December 2003, and worked on soft hadron production. His thesis title is Systematics of Identified Particle Production in pp, d-Au and Au-Au Collisions at RHIC Energies. He graduated in 2006 and now is a Postdoctoral fellow at INFN Sezione di Bari, Italy working on the ALICE experiment at the LHC. Jason Ulery was supported from January 2004 to July 2007. His thesis title is Two- and Three-Particle Jet-Like Correlations. He defended his thesis in October 2007 and is moving to Frankfurt University, Germany to work on the ALICE experiment at the LHC. The research by this grant resulted in 7 journal publications (2 PRL, 1 PLB, 1 PRC, 2 submitted and 1 in preparation), and 14 invited talks and 10 contributed talks at major conferences. These are listed at end of this report.

  16. Measurement of the top quark pair production cross section in proton-antiproton collisions at a center of mass energy of 1.96 TeV, hadronic top decays with the D0 detector

    SciTech Connect (OSTI)

    Hegeman, Jeroen Guido; /Twente U. Tech., Enschede

    2009-01-16

    Of the six quarks in the standard model the top quark is by far the heaviest: 35 times more massive than its partner the bottom quark and more than 130 times heavier than the average of the other five quarks. Its correspondingly small decay width means it tends to decay before forming a bound state. Of all quarks, therefore, the top is the least affected by quark confinement, behaving almost as a free quark. Its large mass also makes the top quark a key player in the realm of the postulated Higgs boson, whose coupling strengths to particles are proportional to their masses. Precision measurements of particle masses for e.g. the top quark and the W boson can hereby provide indirect constraints on the Higgs boson mass. Since in the standard model top quarks couple almost exclusively to bottom quarks (t {yields} Wb), top quark decays provide a window on the standard model through the direct measurement of the Cabibbo-Kobayashi-Maskawa quark mixing matrix element V{sub tb}. In the same way any lack of top quark decays into W bosons could imply the existence of decay channels beyond the standard model, for example charged Higgs bosons as expected in two-doublet Higgs models: t {yields} H{sup +}b. Within the standard model top quark decays can be classified by the (lepton or quark) W boson decay products. Depending on the decay of each of the W bosons, t{bar t} pair decays can involve either no leptons at all, or one or two isolated leptons from direct W {yields} e{bar {nu}}{sub e} and W {yields} {mu}{bar {nu}}{sub {mu}} decays. Cascade decays like b {yields} Wc {yields} e{bar {nu}}{sub e}c can lead to additional non-isolated leptons. The fully hadronic decay channel, in which both Ws decay into a quark-antiquark pair, has the largest branching fraction of all t{bar t} decay channels and is the only kinematically complete (i.e. neutrino-less) channel. It lacks, however, the clear isolated lepton signature and is therefore hard to distinguish from the multi-jet QCD background. It is important to measure the cross section (or branching fraction) in each channel independently to fully verify the standard model. Top quark pair production proceeds through the strong interaction, placing the scene for top quark physics at hadron colliders. This adds an additional challenge: the huge background from multi-jet QCD processes. At the Tevatron, for example, t{bar t} production is completely hidden in light q{bar q} pair production. The light (i.e. not bottom or top) quark pair production cross section is six orders of magnitude larger than that for t{bar t} production. Even including the full signature of hadronic t{bar t} decays, two b-jets and four additional jets, the QCD cross section for processes with similar signature is more than five times larger than for t{bar t} production. The presence of isolated leptons in the (semi)leptonic t{bar t} decay channels provides a clear characteristic to distinguish the t{bar t} signal from QCD background but introduces a multitude of W- and Z-related backgrounds.

  17. Investigation of the dynamics of gluon distributions in the production of heavy quarks and quarkonia at the LEP2 collider

    SciTech Connect (OSTI)

    Lipatov, A. V.

    2006-09-15

    The inclusive production of heavy quarks and quarkonia in photon-photon collisions at the LEP2 collider is considered within the semihard (k{sub T}-factorization) QCD approach. The dependence of the total and differential cross sections for the production of heavy (c and b) quarks and D* and J/{psi} mesons on the choice of unintegrated gluon distribution is studied. The transition of a cc-bar charmed pair to observed J/{psi} mesons is described on the basis of the color-singlet model. The results of the calculations are compared with currently available experimental data obtained by the L3, OPAL, ALEPH, and DELPHI Collaborations. It is shown that the polarization properties of J/{psi} mesons at the LEP2 collider are sensitive to the behavior of unintegrated gluon distributions. This means that experimental investigations of the polarization properties of quarkonia in photon-photon collisions may provide a direct test of the dynamics of gluon distributions in the photon.

  18. The relation between the fundamental scale controlling high-energy interactions of quarks and the proton mass

    SciTech Connect (OSTI)

    Deur, Alexandre; Brodsky, Stanley J.; de Teramond, Guy F.

    2015-04-06

    Quantum Chromodynamics (QCD) provides a fundamental description of the physics binding quarks into protons, neutrons, and other hadrons. QCD is well understood at short distances where perturbative calculations are feasible. Establishing an explicit relation between this regime and the large-distance physics of quark confinement has been a long-sought goal. A major challenge is to relate the parameter Λs, which controls the predictions of perturbative QCD (pQCD) at short distances, to the masses of hadrons. Here we show how new theoretical insights into QCD's behavior at large and small distances lead to an analytical relation between hadronic masses and Λs. The resulting prediction, Λs = 0.341 ± 0.024 GeV agrees well with the experimental value 0.339 ± 0.016 GeV. Conversely, the experimental value of Λs can be used to predict the masses of hadrons, a task which had so far only been accomplished through intensive numerical lattice calculations, requiring several phenomenological input parameters.

  19. Measurement of the Top Quark Mass in the Lepton+Jets Channel Using the Lepton Transverse Momentum

    SciTech Connect (OSTI)

    Aaltonen, T.; Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; /Purdue U. /Waseda U. /Dubna, JINR

    2011-01-01

    This letter reports a measurement of the top quark mass, M{sub top}, in data from p{bar p} collisions at {radical}s = 1.96 TeV corresponding to 2.7 fb{sup -1} of integrated luminosity at the Fermilab Tevatron using the CDF II detector. Events with the lepton+jets topology are selected. An unbinned likelihood is constructed based on the dependence of the lepton transverse momentum, P{sub T}, on M{sub top}. A maximum likelihood fit to the data yields a measured mass M{sub top} = 176.9 {+-} 8.0{sub stat} {+-} 2.7{sub syst} GeV/c{sup 2}. In this measurement, the contribution by the jet energy scale uncertainty to the systematic error is negligible. The result provides an important consistency test for other M{sub top} measurements where explicit use of the jet energy is made for deriving the top quark mass.

  20. Measurement of the Top Quark Mass Using the Invariant Mass of Lepton Pairs in Soft Muon b-tagged Events

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, Jahred A.; Akimoto, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, Dante E.; Anastassov, A.; Annovi, Alberto; Antos, Jaroslav; Apollinari, G.; Apresyan, A.; /Purdue U. /Waseda U.

    2009-06-01

    We present the first measurement of the mass of the top quark in a sample of t{bar t} {yields} {ell}{bar {nu}}b{bar b}q{bar q} events (where {ell} = e, {mu}) selected by identifying jets containing a muon candidate from the semileptonic decay of heavy-flavor hadrons (soft muon b-tagging). The p{bar p} collision data used corresponds to an integrated luminosity of 2 fb{sup -1} and was collected by the CDF II detector at the Fermilab Tevatron. The measurement is based on a novel technique exploiting the invariant mass of a subset of the decay particles, specifically the lepton from the W boson of the t {yields} Wb decay, and the muon from a semileptonic b decay. We fit template histograms, derived from simulation of t{bar t} events and a modeling of the background, to the mass distribution observed in the data and measure a top quark mass of 180.5 {+-} 12.0(stat.) {+-} 3.6(syst.) GeV/c{sup 2}, consistent with the current world average.

  1. Inclusive search for a vector-like T quark with charge $$\\frac{2}{3}$$ in pp collisions at $$\\sqrt{s}$$ = 8 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chatrchyan, Serguei

    2014-01-08

    A search is performed for a massive new vector-like quark T, with charge 2/3, that is pair produced together with its antiparticle in proton-proton collisions. The data were collected by the CMS experiment at the Large Hadron Collider in 2012 at sqrt(s) = 8 TeV and correspond to an integrated luminosity of 19.5 inverse femtobarns. The T quark is assumed to decay into three different final states, bW, tZ, and tH. The search is carried out using events with at least one isolated lepton. No deviations from standard model expectations are observed, and lower limits are set on the Tmore » quark mass at 95% confidence level. The lower limit lies between 687 and 782 GeV for all possible values of the branching fractions into the three different final states assuming strong production. These limits are the most stringent constraints to date on the existence of such a quark.« less

  2. Search for anomalous single top quark production in association with a photon in pp collisions at √(s) = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-11-13

    We found the results of a search for flavor changing neutral currents (FCNC) through single top quark production in association with a photon is presented. The study is based on proton-proton collisions at a center-of-mass energy of 8 TeV using data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.8 fb-1. The search for tγ events where t → Wb andW → μn is conducted in final states with a muon, a photon, at least one hadronic jet with at most one being consistent with originating from a bottom quark, and missing transverse momentum. Furthermore, there was no evidence of single top quark production in association with a photon through a FCNC is observed. Upper limits at the 95% confidence level are set on the tug and tcg anomalous couplings and translated into upper limits on the branching fraction of the FCNC top quark decays: B(t → uγ) < 1.3 x 10-4 and B(t →cγ) < 1.7 x 10-3. Upper limits are also set on the cross section of associated tγ production in a restricted phase-space region. These are the most stringent limits currently available.

  3. Measurement of the Top Quark Mass by Dynamical Likelihood Method using the Lepton + Jets Events with the Collider Detector at Fermilab

    SciTech Connect (OSTI)

    Kubo, Taichi; /Tsukuba U.

    2008-02-01

    We have measured the top quark mass with the dynamical likelihood method. The data corresponding to an integrated luminosity of 1.7fb{sup -1} was collected in proton antiproton collisions at a center of mass energy of 1.96 TeV with the CDF detector at Fermilab Tevatron during the period March 2002-March 2007. We select t{bar t} pair production candidates by requiring one high energy lepton and four jets, in which at least one of jets must be tagged as a b-jet. In order to reconstruct the top quark mass, we use the dynamical likelihood method based on maximum likelihood method where a likelihood is defined as the differential cross section multiplied by the transfer function from observed quantities to parton quantities, as a function of the top quark mass and the jet energy scale(JES). With this method, we measure the top quark mass to be 171.6 {+-} 2.0 (stat.+ JES) {+-} 1.3(syst.) = 171.6 {+-} 2.4 GeV/c{sup 2}.

  4. Measurement of the charge asymmetry in top-quark pair production in proton-proton collisions at sqrt(s) = 7 TeV

    SciTech Connect (OSTI)

    Chatrchyan, Serguei; Khachatryan, Vardan; Sirunyan, Albert M.; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas; Dragicevic, Marko; Erö, Janos; Fabjan, Christian; Friedl, Markus; Fruehwirth, Rudolf; /Yerevan Phys. Inst. /Vienna, OAW /Minsk, High Energy Phys. Ctr. /Antwerp U., WISINF /Vrije U., Brussels /Brussels U. /Gent U. /Louvain U. /UMH, Mons /Rio de Janeiro, CBPF /Rio de Janeiro State U.

    2011-12-01

    The difference in angular distributions between top quarks and antiquarks, commonly referred to as the charge asymmetry, is measured in pp collisions at the LHC with the CMS experiment. The data sample corresponds to an integrated luminosity of 1.09 fb{sup -1} at a centre-of-mass energy of 7 TeV. Top-quark pairs are selected in the final state with an electron or muon and four or more jets. At least one jet is identified as originating from b-quark hadronization. The charge asymmetry is measured in two variables, one based on the pseudorapidities ({eta}) of the top quarks and the other on their rapidities (y). The results A{sub C}{sup {eta}} = -0.017 {+-} 0.032(stat.){sub -0.036}{sup +0.025}(syst.) and A{sub C}{sup y} = -0.013 {+-} 0.028(stat.){sub -0.031}{sup +0.029}(syst.) are consistent within uncertainties with the standard-model predictions.

  5. Measurement of the top-quark mass in the lepton+jets channel using a matrix element technique with the CDF II detector

    SciTech Connect (OSTI)

    Aaltonen, T; Alvarez Gonzalez, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A

    2011-10-14

    A measurement of the top-quark mass is presented using Tevatron data from proton-antiproton collisions at center-of-mass energy ?s = 1.96 TeV collected with the CDF II detector. Events are selected from a sample of candidates for production of tt? pairs that decay into the lepton+jets channel. The top-quark mass is measured with an unbinned maximum likelihood method where the event probability density functions are calculated using signal and background matrix elements, as well as a set of parameterized jet-to-parton transfer functions. The likelihood function is maximized with respect to the top-quark mass, the signal fraction in the sample, and a correction to the jet energy scale (JES) calibration of the calorimeter jets. The simultaneous measurement of the JES correction ({Delta}{sub JES}) amounts to an additional in situ jet energy calibration based on the known mass of the hadronically decaying W boson. Using the data sample of 578 lepton+jets candidate events, corresponding to 3.2 fb-1 of integrated luminosity, the top-quark mass is measured to be mt = 172.4 1.4 (stat + ?JES) 1.3 (syst) GeV/c2.

  6. Measurement of the top-quark mass in the lepton+jets channel using a matrix element technique with the CDF II detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T.

    2011-10-14

    A measurement of the top-quark mass is presented using Tevatron data from proton-antiproton collisions at center-of-mass energy ?s = 1.96 TeV collected with the CDF II detector. Events are selected from a sample of candidates for production of tt? pairs that decay into the lepton+jets channel. The top-quark mass is measured with an unbinned maximum likelihood method where the event probability density functions are calculated using signal and background matrix elements, as well as a set of parameterized jet-to-parton transfer functions. The likelihood function is maximized with respect to the top-quark mass, the signal fraction in the sample, and amorecorrection to the jet energy scale (JES) calibration of the calorimeter jets. The simultaneous measurement of the JES correction ({Delta}{sub JES}) amounts to an additional in situ jet energy calibration based on the known mass of the hadronically decaying W boson. Using the data sample of 578 lepton+jets candidate events, corresponding to 3.2 fb-1 of integrated luminosity, the top-quark mass is measured to be mt = 172.4 1.4 (stat + ?JES) 1.3 (syst) GeV/c2.less

  7. Search for charged Higgs bosons in decays of top quarks in p anti-p collisions at s**(1/2) = 1.96 TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; /Helsinki U. /Helsinki Inst. of Phys.; Adelman, J.; /Chicago U., EFI; Akimoto, T.; /Tsukuba U.; Alvarez Gonzalez, B.; /Cantabria Inst. of Phys.; Amerio, S.; /Padua U. /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U.; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Apresyan, A.; /Purdue U. /Waseda U.

    2009-07-01

    We report on the first direct search for charged Higgs bosons in decays of top quarks in p{bar p} collisions at {radical}s = 1.96 TeV. The search uses a data sample corresponding to an integrated luminosity of 2.2 fb{sup -1} collected by the CDF II detector at Fermilab, and looks for a resonance in the invariant mass distribution of two jets in the lepton+jets sample of t{bar t} candidates. We observe no evidence of charged Higgs bosons in top quark decays. Hence, 95% upper limits on the top quark decay branching ratio are placed at {Beta}(t {yields} H{sup +}b) < 0.1 to 0.3 for charged Higgs boson masses of 60 to 150 GeV/c{sup 2}, assuming {Beta}(H{sup +} {yields} c{bar s}) = 1.0. The upper limits on {Beta}(t {yields} H{sup +}b) can also be used as model-independent limits on the decay branching ratio of top quarks to generic scalar charged bosons beyond the standard model.

  8. Search for vector-like charge 2/3 T quarks in proton-proton collisions at $\\sqrt{s}$ = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-09-15

    Our search for fermionic top quark partners T of charge 2/3 is presented. The search is carried out in proton-proton collisions corresponding to an integrated luminosity of 19.7 fb-1 collected at a center-of-mass energy of √s = 8 TeV with the CMS detector at the LHC. The T quarks are assumed to be produced strongly in pairs and can decay into tH, tZ, and bW. The search is performed in five exclusive channels: a singlelepton channel, a multilepton channel, two all-hadronic channels optimized either for the bW or the tH decay, and one channel in which the Higgs boson decays into two photons. The results are found to be compatible with the standard model expectations in all the investigated final states. Finally, a statistical combination of these results is performed and lower limits on the T quark mass are set. Depending on the branching fractions, lower mass limits between 720 and 920 GeV at 95% confidence level are found. These are among the strongest limits on vector-like T quarks obtained to date.

  9. Measurement of the Top Quark Mass and ppbar -> ttbar Cross Section in the All-Hadronic Mode with the CDFII Detector

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.; Apresyan, A.; /Purdue U. /Waseda U.

    2010-02-01

    We present a measurement of the top quark mass and of the top-antitop pair production cross section using p{bar p} data collected with the CDF II detector at the Tevatron Collider at the Fermi National Accelerator Laboratory and corresponding to an integrated luminosity of 2.9 fb{sup -1}. We select events with six or more jets satisfying a number of kinematical requirements imposed by means of a neural network algorithm. At least one of these jets must originate from a b quark, as identified by the reconstruction of a secondary vertex inside the jet. The mass measurement is based on a likelihood fit incorporating reconstructed mass distributions representative of signal and background, where the absolute jet energy scale (JES) is measured simultaneously with the top quark mass. The measurement yields a value of 174.8 {+-} 2.4(stat+JES){sub -1.0}{sup +1.2}(syst)GeV/c{sup 2}, where the uncertainty from the absolute jet energy scale is evaluated together with the statistical uncertainty. The procedure measures also the amount of signal from which we derive a cross section, {sigma}{sub t{bar t}} = 7.2 {+-} 0.5(stat) {+-} 1.0(syst) {+-} 0.4(lum) pb, for the measured values of top quark mass and JES.

  10. Measurement of the top-quark mass in the lepton+jets channel using a matrix element technique with the CDF II detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T.

    2011-10-14

    A measurement of the top-quark mass is presented using Tevatron data from proton-antiproton collisions at center-of-mass energy √s = 1.96 TeV collected with the CDF II detector. Events are selected from a sample of candidates for production of tt̄ pairs that decay into the lepton+jets channel. The top-quark mass is measured with an unbinned maximum likelihood method where the event probability density functions are calculated using signal and background matrix elements, as well as a set of parameterized jet-to-parton transfer functions. The likelihood function is maximized with respect to the top-quark mass, the signal fraction in the sample, and amore » correction to the jet energy scale (JES) calibration of the calorimeter jets. The simultaneous measurement of the JES correction ({Delta}{sub JES}) amounts to an additional in situ jet energy calibration based on the known mass of the hadronically decaying W boson. Using the data sample of 578 lepton+jets candidate events, corresponding to 3.2 fb-1 of integrated luminosity, the top-quark mass is measured to be mt = 172.4± 1.4 (stat + ΔJES) ± 1.3 (syst) GeV/c2.« less

  11. Semi-inclusive charged-pion electroproduction off protons and deuterons: Cross sections, ratios, and access to the quark-parton model at low energies

    SciTech Connect (OSTI)

    Asaturyan, R.; Ent, R.; Mkrtchyan, H.; Navasardyan, T.; Tadevosyan, V.; Adams, G. S.; Ahmidouch, A.; Angelescu, T.; Arrington, J.; Asaturyan, A.; Baker, O. K.; Benmouna, N.; Bertoncini, C.; Blok, H. P.; Boeglin, W. U.; Bosted, P. E.; Breuer, H.; Christy, M. E.; Connell, S. H.; Cui, Y.; Dalton, M. M.; Danagoulian, S.; Day, D.; Dunne, J. A.; Dutta, D.; El Khayari, N.; Fenker, H. C.; Frolov, V. V.; Gan, L.; Gaskell, D.; Hafidi, K.; Hinton, W.; Holt, R. J.; Horn, T.; Huber, G. M.; Hungerford, E.; Jiang, X.; Jones, M.; Joo, K.; Kalantarians, N.; Kelly, J. J.; Keppel, C. E.; Kubarovsky, V.; Li, Y.; Liang, Y.; Mack, D.; Malace, S. P.; Markowitz, P.; McGrath, E.; McKee, P.; Meekins, D. G.; Mkrtchyan, A.; Moziak, B.; Niculescu, G.; Niculescu, I.; Opper, A. K.; Ostapenko, T.; Reimer, P. E.; Reinhold, J.; Roche, J.; Rock, S. E.; Schulte, E.; Segbefia, E.; Smith, C.; Smith, G. R.; Stoler, P.; Tang, L.; Ungaro, M.; Uzzle, A.; Vidakovic, S.; Villano, A.; Vulcan, W. F.; Wang, M.; Warren, G.; Wesselmann, F. R.; Wojtsekhowski, B.; Wood, S. A.; Xu, C.; Yuan, L.; Zheng, X.

    2012-01-01

    A large set of cross sections for semi-inclusive electroproduction of charged pions (?) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared W2 > 4 GeV2 and range in four-momentum transfer squared 2 < Q2 < 4 (GeV/c)2, and cover a range in the Bjorken scaling variable 0.2 < x < 0.6. The fractional energy of the pions spans a range 0.3 < z < 1, with small transverse momenta with respect to the virtual-photon direction, Pt2 < 0.2 (GeV/c)2. The invariant mass that goes undetected, Mx or W', is in the nucleon resonance region, W' < 2 GeV. The new data conclusively show the onset of quark-hadron duality in this process, and the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark ? pion production mechanisms. The x, z and Pt2 dependences of several ratios (the ratios of favored-unfavored fragmentation functions, charged pion ratios, deuteron-hydrogen and aluminum-deuteron ratios for ?+ and ?-) have been studied. The ratios are found to be in good agreement with expectations based upon a high-energy quark-parton model description. We find the azimuthal dependences to be small, as compared to exclusive pion electroproduction, and consistent with theoretical expectations based on tree-level factorization in terms of transverse-momentum-dependent parton distribution and fragmentation functions. In the context of a simple model, the initial transverse momenta of d quarks are found to be slightly smaller than for u quarks, while the transverse momentum width of the favored fragmentation function is about the same as for the unfavored one, and both fragmentation widths are larger than the quark widths.

  12. Search for the standard model Higgs boson produced in association with top quarks using the full CDF data set

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Arisawa, T.; Artikov, A.; /Dubna, JINR /Texas A-M

    2012-08-01

    A search is presented for the standard model Higgs boson produced in association with top quarks using the full Run II proton-antiproton collision data set, corresponding to 9.45 fb{sup -1}, collected by the Collider Detector at Fermilab. No significant excess over the expected background is observed, and 95% credibility-level upper bounds are placed on the cross section {sigma}(t{bar t}H {yields} lepton + missing transverse energy + jets). For a Higgs boson mass of 125 GeV/c{sup 2}, we expect to set a limit of 12.6, and observe a limit of 20.5 times the standard model rate. This represents the most sensitive search for a standard model Higgs boson in this channel to date.

  13. Measurement of the W boson helicity in top quark decays using 5.4 fb? of pp? collision data

    SciTech Connect (OSTI)

    Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G. A.; Ancu, L. S.; Aoki, M.; Arnoud, Y.; Arov, M.; Askew, A.; sman, B.; Atramentov, O.; Avila, C.; BackusMayes, J.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Beale, S.; Bean, A.; Begalli, M.; Begel, M.; Belanger-Champagne, C.; Bellantoni, L.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besanon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; Bolton, T. A.; Boos, E. E.; Borissov, G.; Bose, T.; Brandt, A.; Brandt, O.; Brock, R.; Brooijmans, G.; Bross, A.; Brown, D.; Brown, J.; Bu, X. B.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Burnett, T. H.; Buszello, C. P.; Calpas, B.; Camacho-Prez, E.; Carrasco-Lizarraga, M. A.; Casey, B. C. K.; Castilla-Valdez, H.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chen, G.; Chevalier-Thry, S.; Cho, D. K.; Cho, S. W.; Choi, S.; Choudhary, B.; Christoudias, T.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M.-C.; Croc, A.; Cutts, D.; ?wiok, M.; Das, A.; Davies, G.; De, K.; de Jong, S. J.; De La Cruz-Burelo, E.; Dliot, F.; Demarteau, M.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Dominguez, A.; Dorland, T.; Dubey, A.; Dudko, L. V.; Duggan, D.; Duperrin, A.; Dutt, S.; Dyshkant, A.; Eads, M.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Enari, Y.; Evans, H.; Evdokimov, A.; Evdokimov, V. N.; Facini, G.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Gadfort, T.; Garcia-Bellido, A.; Gavrilov, V.; Gay, P.; Geist, W.; Geng, W.; Gerbaudo, D.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Golovanov, G.; Goussiou, A.; Grannis, P. D.; Greder, S.; Greenlee, H.; Greenwood, Z. D.; Gregores, E. M.; Grenier, G.; Gris, Ph.; Grivaz, J.-F.; Grohsjean, A.; Grnendahl, S.; Grnewald, M. W.; Guo, F.; Gutierrez, G.; Gutierrez, P.; Haas, A.; Hagopian, S.; Haley, J.; Han, L.; Harder, K.; Harel, A.; Hauptman, J. M.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hoeneisen, B.; Hohlfeld, M.; Hossain, S.; Hubacek, Z.; Huske, N.; Hynek, V.; Iashvili, I.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffr, M.; Jain, S.; Jamin, D.; Jesik, R.; Johns, K.; Johnson, M.; Johnston, D.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Juste, A.; Kaadze, K.; Kajfasz, E.; Karmanov, D.; Kasper, P. A.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Khatidze, D.; Kirby, M. H.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kumar, A.; Kupco, A.; Kur?a, T.; Kuzmin, V. A.; Kvita, J.; Lammers, S.; Landsberg, G.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lellouch, J.; Li, L.; Li, Q. Z.; Lietti, S. M.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, Y.; Liu, Z.; Lobodenko, A.; Lokajicek, M.; Love, P.; Lubatti, H. J.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Mackin, D.; Madar, R.; Magaa-Villalba, R.; Malik, S.; Malyshev, V. L.; Maravin, Y.; Martnez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Meyer, A.; Meyer, J.; Mondal, N. K.; Muanza, G. S.; Mulhearn, M.; Nagy, E.; Naimuddin, M.; Narain, M.; Nayyar, R.; Neal, H. A.; Negret, J. P.; Neustroev, P.; Novaes, S. F.; Nunnemann, T.; Obrant, G.; Orduna, J.; Osman, N.; Osta, J.; Otero y Garzn, G. J.; Owen, M.; Padilla, M.; Pangilinan, M.; Parashar, N.; Parihar, V.; Park, S. K.; Parsons, J.; Partridge, R.; Parua, N.; Patwa, A.; Penning, B.; Perfilov, M.; Peters, K.; Peters, Y.; Petrillo, G.; Ptroff, P.; Piegaia, R.; Piper, J.; Pleier, M.-A.; Podesta-Lerma, P. L. M.; Podstavkov, V.M.; Pol, M.-E.; Polozov, P.; Popov, A. V.; Prewitt, M.; Price, D.; Protopopescu, S.; Qian, J.; Quadt, A.; Quinn, B.; Rangel, M. S.; Ranjan, K.; Ratoff, P. N.; Razumov, I.; Renkel, P.; Rich, P.; Rijssenbeek, M.; Ripp-Baudot, I.; Rizatdinova, F.; Rominsky, M.; Royon, C.; Rubinov, P.; Ruchti, R.; Safronov, G.; Sajot, G.; Snchez-Hernndez, A.; Sanders, M. P.; Sanghi, B.; Santos, A. S.; Savage, G.; Sawyer, L.; Scanlon, T.; Schamberger, R. D.; Scheglov, Y.; Schellman, H.; Schliephake, T.; Schlobohm, S.; Schwanenberger, C.; Schwienhorst, R.; Sekaric, J.; Severini, H.; Shabalina, E.; Shary, V.; Shchukin, A. A.; Shivpuri, R. K.; Simak, V.; Sirotenko, V.; Skubic, P.; Slattery, P.; Smirnov, D.

    2011-02-18

    We present a measurement of the helicity of the W boson produced in top quark decays using tt decays in the l+jets and dilepton final states selected from a sample of 5.4 fb? of collisions recorded using the D0 detector at the Fermilab Tevatron pp? collider. We measure the fractions of longitudinal and right-handed W bosons to be f?=0.6690.102[0.078(stat.)0.065(syst.)] and f?=0.0230.053[0.041(stat.)0.034(syst.)], respectively. This result is consistent at the 98% level with the standard model. A measurement with f? fixed to the value from the standard model yields f?=0.0100.037[0.022(stat.)0.030(syst.)].

  14. Search for flavour-changing neutral current top quark decays t → Hq in pp collisions at √s = 8 TeV with the ATLAS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; et al

    2015-12-10

    A search for flavour-changing neutral current decays of a top quark to an uptype quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to bb¯, is presented. The analysis searches for top quark pair events in which one top quark decays to Wb, with the W boson decaying leptonically, and the other top quark decays to Hq. The search is based on pp collisions at √s = 8 TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and uses an integrated luminosity of 20.3 fb-1. Data are analysedmore » in the lepton-plus-jets final state, characterised by an isolated electron or muon and at least four jets. The search exploits the high multiplicity of b-quark jets characteristic of signal events, and employs a likelihood discriminant that uses the kinematic differences between the signal and the background, which is dominated by tt¯→ WbWb decays. No significant excess of events above the background expectation is found, and observed (expected) 95% CL upper limits of 0.56% (0.42%) and 0.61% (0.64%) are derived for the t → Hc and t → Hu branching ratios respectively. The combination of this search with other ATLAS searches in the H → γγ and H → WW*, ττ decay modes significantly improves the sensitivity, yielding observed (expected) 95% CL upper limits on the t → Hc and t → Hu branching ratios of 0.46% (0.25%) and 0.45% (0.29%) respectively. The corresponding combined observed (expected) upper limits on the |λ tcH | and |λ tuH | couplings are 0.13 (0.10) and 0.13 (0.10) respectively. As a result, these are the most restrictive direct bounds on tqH interactions measured so far.« less

  15. Search for flavour-changing neutral current top quark decays t → Hq in pp collisions at √s = 8 TeV with the ATLAS detector

    SciTech Connect (OSTI)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Adelman, J.; Adomeit, S.; Adye, T.; Affolder, A. A.; Agatonovic-Jovin, T.; Agricola, J.; Aguilar-Saavedra, J. A.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akerstedt, H.; Åkesson, T. P. A.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albrand, S.; Alconada Verzini, M. J.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Alimonti, G.; Alio, L.; Alison, J.; Alkire, S. P.; Allbrooke, B. M. M.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Altheimer, A.; Alvarez Gonzalez, B.; Álvarez Piqueras, D.; Alviggi, M. G.; Amadio, B. T.; Amako, K.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amram, N.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anders, J. K.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Angelidakis, S.; Angelozzi, I.; Anger, P.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Arabidze, G.; Arai, Y.; Araque, J. P.; Arce, A. T. H.; Arduh, F. A.; Arguin, J-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnold, H.; Arratia, M.; Arslan, O.; Artamonov, A.; Artoni, G.; Asai, S.; Asbah, N.; Ashkenazi, A.; Åsman, B.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Augsten, K.; Aurousseau, M.; Avolio, G.; Axen, B.; Ayoub, M. K.; Azuelos, G.; Baak, M. A.; Baas, A. E.; Baca, M. J.; Bacci, C.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Bain, T.; Baines, J. T.; Baker, O. K.; Baldin, E. M.; Balek, P.; Balestri, T.; Balli, F.; Balunas, W. K.; Banas, E.; Banerjee, Sw.; Bannoura, A. A. E.; Barak, L.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnes, S. L.; Barnett, B. M.; Barnett, R. M.; Barnovska, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Bartoldus, R.; Barton, A. E.; Bartos, P.; Basalaev, A.; Bassalat, A.; Basye, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, M.; Bauer, F.; Bawa, H. S.; Beacham, J. B.; Beattie, M. D.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, M.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Behr, J. K.; Belanger-Champagne, C.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Benary, O.; Benchekroun, D.; Bender, M.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez Garcia, J. A.; Benjamin, D. P.; Bensinger, J. R.; Bentvelsen, S.; Beresford, L.; Beretta, M.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Beringer, J.; Bernard, C.; Bernard, N. R.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertoli, G.; Bertolucci, F.; Bertsche, C.; Bertsche, D.; Besana, M. I.; Besjes, G. J.; Bessidskaia Bylund, O.; Bessner, M.; Besson, N.; Betancourt, C.; Bethke, S.; Bevan, A. J.; Bhimji, W.; Bianchi, R. M.; Bianchini, L.; Bianco, M.; Biebel, O.; Biedermann, D.; Biesuz, N. V.; Biglietti, M.; Bilbao De Mendizabal, J.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biondi, S.; Bjergaard, D. M.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blanchard, J. -B.; Blanco, J. E.; Blazek, T.; Bloch, I.; Blocker, C.; Blum, W.; Blumenschein, U.; Blunier, S.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Bock, C.; Boehler, M.; Bogaerts, J. A.; Bogavac, D.; Bogdanchikov, A. G.; Bohm, C.; Boisvert, V.; Bold, T.; Boldea, V.; Boldyrev, A. S.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Borroni, S.; Bortfeldt, J.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Bousson, N.; Boutle, S. K.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozic, I.; Bracinik, J.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Breaden Madden, W. D.; Brendlinger, K.; Brennan, A. J.; Brenner, L.; Brenner, R.; Bressler, S.; Bristow, T. M.; Britton, D.; Britzger, D.; Brochu, F. M.; Brock, I.; Brock, R.; Bronner, J.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Bruni, A.; Bruni, G.; Bruschi, M.; Bruscino, N.; Bryngemark, L.; Buanes, T.; Buat, Q.; Buchholz, P.; Buckley, A. G.; Budagov, I. A.; Buehrer, F.; Bugge, L.; Bugge, M. K.; Bulekov, O.; Bullock, D.; Burckhart, H.; Burdin, S.; Burgard, C. D.; Burghgrave, B.; Burke, S.; Burmeister, I.; Busato, E.; Büscher, D.; Büscher, V.; Bussey, P.; Butler, J. M.; Butt, A. I.; Buttar, C. M.; Butterworth, J. M.; Butti, P.; Buttinger, W.; Buzatu, A.; Buzykaev, A. R.; Cabrera Urbán, S.; Caforio, D.; Cairo, V. M.; Cakir, O.; Calace, N.; Calafiura, P.; Calandri, A.; Calderini, G.; Calfayan, P.; Caloba, L. P.; Calvet, D.; Calvet, S.; Camacho Toro, R.; Camarda, S.; Camarri, P.; Cameron, D.; Caminal Armadans, R.; Campana, S.; Campanelli, M.; Campoverde, A.; Canale, V.; Canepa, A.; Cano Bret, M.; Cantero, J.; Cantrill, R.; Cao, T.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capua, M.; Caputo, R.; Carbone, R. M.; Cardarelli, R.; Cardillo, F.; Carli, T.; Carlino, G.; Carminati, L.; Caron, S.; Carquin, E.; Carrillo-Montoya, G. D.; Carter, J. R.; Carvalho, J.; Casadei, D.; Casado, M. P.; Casolino, M.; Casper, D. W.; Castaneda-Miranda, E.; Castelli, A.; Castillo Gimenez, V.; Castro, N. F.; Catastini, P.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Caudron, J.; Cavaliere, V.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Ceradini, F.; Cerda Alberich, L.; Cerio, B. C.; Cerny, K.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cerv, M.; Cervelli, A.; Cetin, S. A.; Chafaq, A.; Chakraborty, D.; Chalupkova, I.; Chan, Y. L.; Chang, P.; Chapman, J. D.; Charlton, D. G.; Chau, C. C.; Chavez Barajas, C. A.; Cheatham, S.; Chegwidden, A.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, K.; Chen, L.; Chen, S.; Chen, S.; Chen, X.; Chen, Y.; Cheng, H. C.; Cheng, Y.; Cheplakov, A.; Cheremushkina, E.; Cherkaoui El Moursli, R.; Chernyatin, V.; Cheu, E.; Chevalier, L.; Chiarella, V.; Chiarelli, G.; Chiodini, G.; Chisholm, A. S.; Chislett, R. T.; Chitan, A.; Chizhov, M. V.; Choi, K.; Chouridou, S.; Chow, B. K. B.; Christodoulou, V.; Chromek-Burckhart, D.; Chudoba, J.; Chuinard, A. J.; Chwastowski, J. J.; Chytka, L.; Ciapetti, G.; Ciftci, A. K.; Cinca, D.; Cindro, V.; Cioara, I. A.; Ciocio, A.; Cirotto, F.; Citron, Z. H.; Ciubancan, M.; Clark, A.; Clark, B. L.; Clark, P. J.; Clarke, R. N.; Clement, C.; Coadou, Y.; Cobal, M.; Coccaro, A.; Cochran, J.; Coffey, L.; Cogan, J. G.; Colasurdo, L.; Cole, B.; Cole, S.; Colijn, A. P.; Collot, J.; Colombo, T.; Compostella, G.; Conde Muiño, P.; Coniavitis, E.; Connell, S. H.; Connelly, I. A.; Consorti, V.; Constantinescu, S.; Conta, C.; Conti, G.; Conventi, F.; Cooke, M.; Cooper, B. D.; Cooper-Sarkar, A. M.; Cornelissen, T.; Corradi, M.; Corriveau, F.; Corso-Radu, A.; Cortes-Gonzalez, A.; Cortiana, G.; Costa, G.; Costa, M. J.; Costanzo, D.; Côté, D.; Cottin, G.; Cowan, G.; Cox, B. E.; Cranmer, K.; Cree, G.; Crépé-Renaudin, S.; Crescioli, F.; Cribbs, W. A.; Crispin Ortuzar, M.; Cristinziani, M.; Croft, V.; Crosetti, G.; Cuhadar Donszelmann, T.; Cummings, J.; Curatolo, M.; Cúth, J.; Cuthbert, C.; Czirr, H.; Czodrowski, P.; D’Auria, S.; D’Onofrio, M.; Da Cunha Sargedas De Sousa, M. J.; Da Via, C.; Dabrowski, W.; Dafinca, A.; Dai, T.; Dale, O.; Dallaire, F.; Dallapiccola, C.; Dam, M.; Dandoy, J. R.; Dang, N. P.; Daniells, A. C.; Danninger, M.; Dano Hoffmann, M.; Dao, V.; Darbo, G.; Darmora, S.; Dassoulas, J.; Dattagupta, A.; Davey, W.; David, C.; Davidek, T.; Davies, E.; Davies, M.; Davison, P.; Davygora, Y.; Dawe, E.; Dawson, I.; Daya-Ishmukhametova, R. K.; De, K.; de Asmundis, R.; De Benedetti, A.; De Castro, S.; De Cecco, S.; De Groot, N.; de Jong, P.; De la Torre, H.; De Lorenzi, F.; De Pedis, D.; De Salvo, A.; De Sanctis, U.; De Santo, A.; De Vivie De Regie, J. B.; Dearnaley, W. J.; Debbe, R.; Debenedetti, C.; Dedovich, D. V.; Deigaard, I.; Del Peso, J.; Del Prete, T.; Delgove, D.; Deliot, F.; Delitzsch, C. M.; Deliyergiyev, M.; Dell’Acqua, A.; Dell’Asta, L.; Dell’Orso, M.; Della Pietra, M.; della Volpe, D.; Delmastro, M.; Delsart, P. A.; Deluca, C.; DeMarco, D. A.; Demers, S.; Demichev, M.; Demilly, A.; Denisov, S. P.; Derendarz, D.; Derkaoui, J. E.; Derue, F.; Dervan, P.; Desch, K.; Deterre, C.; Dette, K.; Deviveiros, P. O.; Dewhurst, A.; Dhaliwal, S.; Di Ciaccio, A.; Di Ciaccio, L.; Di Domenico, A.; Di Donato, C.; Di Girolamo, A.; Di Girolamo, B.; Di Mattia, A.; Di Micco, B.; Di Nardo, R.; Di Simone, A.; Di Sipio, R.; Di Valentino, D.; Diaconu, C.; Diamond, M.; Dias, F. A.; Diaz, M. A.; Diehl, E. B.; Dietrich, J.; Diglio, S.; Dimitrievska, A.; Dingfelder, J.; Dita, P.; Dita, S.; Dittus, F.; Djama, F.; Djobava, T.; Djuvsland, J. I.; do Vale, M. A. B.; Dobos, D.; Dobre, M.; Doglioni, C.; Dohmae, T.; Dolejsi, J.; Dolezal, Z.; Dolgoshein, B. A.; Donadelli, M.; Donati, S.; Dondero, P.; Donini, J.; Dopke, J.; Doria, A.; Dova, M. T.; Doyle, A. T.; Drechsler, E.; Dris, M.; Du, Y.; Dubreuil, E.; Duchovni, E.; Duckeck, G.; Ducu, O. A.; Duda, D.; Dudarev, A.; Duflot, L.; Duguid, L.; Dührssen, M.; Dunford, M.; Duran Yildiz, H.; Düren, M.; Durglishvili, A.; Duschinger, D.; Dutta, B.; Dyndal, M.; Eckardt, C.; Ecker, K. M.; Edgar, R. C.; Edson, W.; Edwards, N. C.; Ehrenfeld, W.; Eifert, T.; Eigen, G.; Einsweiler, K.; Ekelof, T.; El Kacimi, M.; Ellert, M.; Elles, S.; Ellinghaus, F.; Elliot, A. A.; Ellis, N.; Elmsheuser, J.; Elsing, M.; Emeliyanov, D.; Enari, Y.; Endner, O. C.; Endo, M.; Erdmann, J.; Ereditato, A.; Ernis, G.; Ernst, J.; Ernst, M.; Errede, S.; Ertel, E.; Escalier, M.; Esch, H.; Escobar, C.; Esposito, B.; Etienvre, A. I.; Etzion, E.; Evans, H.; Ezhilov, A.; Fabbri, L.; Facini, G.; Fakhrutdinov, R. M.; Falciano, S.; Falla, R. J.; Faltova, J.; Fang, Y.; Fanti, M.; Farbin, A.; Farilla, A.; Farooque, T.; Farrell, S.; Farrington, S. M.; Farthouat, P.; Fassi, F.; Fassnacht, P.; Fassouliotis, D.; Faucci Giannelli, M.; Favareto, A.; Fayard, L.; Fedin, O. L.; Fedorko, W.; Feigl, S.; Feligioni, L.; Feng, C.; Feng, E. J.; Feng, H.; Fenyuk, A. B.; Feremenga, L.; Fernandez Martinez, P.; Fernandez Perez, S.; Ferrando, J.; Ferrari, A.; Ferrari, P.; Ferrari, R.; Ferreira de Lima, D. E.; Ferrer, A.; Ferrere, D.; Ferretti, C.; Ferretto Parodi, A.; Fiascaris, M.; Fiedler, F.; Filipčič, A.; Filipuzzi, M.; Filthaut, F.; Fincke-Keeler, M.; Finelli, K. D.; Fiolhais, M. C. N.; Fiorini, L.; Firan, A.; Fischer, A.; Fischer, C.; Fischer, J.; Fisher, W. C.; Flaschel, N.; Fleck, I.; Fleischmann, P.; Fletcher, G. T.; Fletcher, G.; Fletcher, R. R. M.; Flick, T.; Floderus, A.; Flores Castillo, L. R.; Flowerdew, M. J.; Formica, A.; Forti, A.; Fournier, D.; Fox, H.; Fracchia, S.; Francavilla, P.; Franchini, M.; Francis, D.; Franconi, L.; Franklin, M.; Frate, M.; Fraternali, M.; Freeborn, D.; French, S. T.; Fressard-Batraneanu, S. 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S.; Polychronakos, V.; Pommès, K.; Pontecorvo, L.; Pope, B. G.; Popeneciu, G. A.; Popovic, D. S.; Poppleton, A.; Pospisil, S.; Potamianos, K.; Potrap, I. N.; Potter, C. J.; Potter, C. T.; Poulard, G.; Poveda, J.; Pozdnyakov, V.; Pozo Astigarraga, M. E.; Pralavorio, P.; Pranko, A.; Prasad, S.; Prell, S.; Price, D.; Price, L. E.; Primavera, M.; Prince, S.; Proissl, M.; Prokofiev, K.; Prokoshin, F.; Protopapadaki, E.; Protopopescu, S.; Proudfoot, J.; Przybycien, M.; Ptacek, E.; Puddu, D.; Pueschel, E.; Puldon, D.; Purohit, M.; Puzo, P.; Qian, J.; Qin, G.; Qin, Y.; Quadt, A.; Quarrie, D. R.; Quayle, W. B.; Queitsch-Maitland, M.; Quilty, D.; Raddum, S.; Radeka, V.; Radescu, V.; Radhakrishnan, S. K.; Radloff, P.; Rados, P.; Ragusa, F.; Rahal, G.; Rajagopalan, S.; Rammensee, M.; Rangel-Smith, C.; Rauscher, F.; Rave, S.; Ravenscroft, T.; Raymond, M.; Read, A. L.; Readioff, N. P.; Rebuzzi, D. M.; Redelbach, A.; Redlinger, G.; Reece, R.; Reeves, K.; Rehnisch, L.; Reichert, J.; Reisin, H.; Rembser, C.; Ren, H.; Renaud, A.; Rescigno, M.; Resconi, S.; Rezanova, O. L.; Reznicek, P.; Rezvani, R.; Richter, R.; Richter, S.; Richter-Was, E.; Ricken, O.; Ridel, M.; Rieck, P.; Riegel, C. J.; Rieger, J.; Rifki, O.; Rijssenbeek, M.; Rimoldi, A.; Rinaldi, L.; Ristić, B.; Ritsch, E.; Riu, I.; Rizatdinova, F.; Rizvi, E.; Robertson, S. H.; Robichaud-Veronneau, A.; Robinson, D.; Robinson, J. E. M.; Robson, A.; Roda, C.; Roe, S.; Røhne, O.; Romaniouk, A.; Romano, M.; Romano Saez, S. M.; Romero Adam, E.; Rompotis, N.; Ronzani, M.; Roos, L.; Ros, E.; Rosati, S.; Rosbach, K.; Rose, P.; Rosendahl, P. L.; Rosenthal, O.; Rossetti, V.; Rossi, E.; Rossi, L. P.; Rosten, J. H. N.; Rosten, R.; Rotaru, M.; Roth, I.; Rothberg, J.; Rousseau, D.; Royon, C. R.; Rozanov, A.; Rozen, Y.; Ruan, X.; Rubbo, F.; Rubinskiy, I.; Rud, V. I.; Rudolph, C.; Rudolph, M. S.; Rühr, F.; Ruiz-Martinez, A.; Rurikova, Z.; Rusakovich, N. A.; Ruschke, A.; Russell, H. L.; Rutherfoord, J. P.; Ruthmann, N.; Ryabov, Y. F.; Rybar, M.; Rybkin, G.; Ryder, N. C.; Saavedra, A. F.; Sabato, G.; Sacerdoti, S.; Saddique, A.; Sadrozinski, H. F-W.; Sadykov, R.; Safai Tehrani, F.; Saha, P.; Sahinsoy, M.; Saimpert, M.; Saito, T.; Sakamoto, H.; Sakurai, Y.; Salamanna, G.; Salamon, A.; Salazar Loyola, J. E.; Saleem, M.; Salek, D.; Sales De Bruin, P. H.; Salihagic, D.; Salnikov, A.; Salt, J.; Salvatore, D.; Salvatore, F.; Salvucci, A.; Salzburger, A.; Sammel, D.; Sampsonidis, D.; Sanchez, A.; Sánchez, J.; Sanchez Martinez, V.; Sandaker, H.; Sandbach, R. L.; Sander, H. G.; Sanders, M. P.; Sandhoff, M.; Sandoval, C.; Sandstroem, R.; Sankey, D. P. C.; Sannino, M.; Sansoni, A.; Santoni, C.; Santonico, R.; Santos, H.; Santoyo Castillo, I.; Sapp, K.; Sapronov, A.; Saraiva, J. G.; Sarrazin, B.; Sasaki, O.; Sasaki, Y.; Sato, K.; Sauvage, G.; Sauvan, E.; Savage, G.; Savard, P.; Sawyer, C.; Sawyer, L.; Saxon, J.; Sbarra, C.; Sbrizzi, A.; Scanlon, T.; Scannicchio, D. A.; Scarcella, M.; Scarfone, V.; Schaarschmidt, J.; Schacht, P.; Schaefer, D.; Schaefer, R.; Schaeffer, J.; Schaepe, S.; Schaetzel, S.; Schäfer, U.; Schaffer, A. C.; Schaile, D.; Schamberger, R. D.; Scharf, V.; Schegelsky, V. A.; Scheirich, D.; Schernau, M.; Schiavi, C.; Schillo, C.; Schioppa, M.; Schlenker, S.; Schmieden, K.; Schmitt, C.; Schmitt, S.; Schmitt, S.; Schmitz, S.; Schneider, B.; Schnellbach, Y. J.; Schnoor, U.; Schoeffel, L.; Schoening, A.; Schoenrock, B. D.; Schopf, E.; Schorlemmer, A. L. S.; Schott, M.; Schouten, D.; Schovancova, J.; Schramm, S.; Schreyer, M.; Schuh, N.; Schultens, M. J.; Schultz-Coulon, H. -C.; Schulz, H.; Schumacher, M.; Schumm, B. A.; Schune, Ph.; Schwanenberger, C.; Schwartzman, A.; Schwarz, T. A.; Schwegler, Ph.; Schweiger, H.; Schwemling, Ph.; Schwienhorst, R.; Schwindling, J.; Schwindt, T.; Sciacca, F. G.; Scifo, E.; Sciolla, G.; Scuri, F.; Scutti, F.; Searcy, J.; Sedov, G.; Sedykh, E.; Seema, P.; Seidel, S. C.; Seiden, A.; Seifert, F.; Seixas, J. M.; Sekhniaidze, G.; Sekhon, K.; Sekula, S. J.; Seliverstov, D. M.; Semprini-Cesari, N.; Serfon, C.; Serin, L.; Serkin, L.; Serre, T.; Sessa, M.; Seuster, R.; Severini, H.; Sfiligoj, T.; Sforza, F.; Sfyrla, A.; Shabalina, E.; Shamim, M.; Shan, L. Y.; Shang, R.; Shank, J. T.; Shapiro, M.; Shatalov, P. B.; Shaw, K.; Shaw, S. M.; Shcherbakova, A.; Shehu, C. Y.; Sherwood, P.; Shi, L.; Shimizu, S.; Shimmin, C. O.; Shimojima, M.; Shiyakova, M.; Shmeleva, A.; Shoaleh Saadi, D.; Shochet, M. J.; Shojaii, S.; Shrestha, S.; Shulga, E.; Shupe, M. A.; Sicho, P.; Sidebo, P. E.; Sidiropoulou, O.; Sidorov, D.; Sidoti, A.; Siegert, F.; Sijacki, Dj.; Silva, J.; Silver, Y.; Silverstein, S. B.; Simak, V.; Simard, O.; Simic, Lj.; Simion, S.; Simioni, E.; Simmons, B.; Simon, D.; Sinervo, P.; Sinev, N. B.; Sioli, M.; Siragusa, G.; Sisakyan, A. N.; Sivoklokov, S. Yu.; Sjölin, J.; Sjursen, T. B.; Skinner, M. B.; Skottowe, H. P.; Skubic, P.; Slater, M.; Slavicek, T.; Slawinska, M.; Sliwa, K.; Smakhtin, V.; Smart, B. H.; Smestad, L.; Smirnov, S. Yu.; Smirnov, Y.; Smirnova, L. N.; Smirnova, O.; Smith, M. N. K.; Smith, R. W.; Smizanska, M.; Smolek, K.; Snesarev, A. A.; Snidero, G.; Snyder, S.; Sobie, R.; Socher, F.; Soffer, A.; Soh, D. A.; Sokhrannyi, G.; Solans, C. A.; Solar, M.; Solc, J.; Soldatov, E. Yu.; Soldevila, U.; Solodkov, A. A.; Soloshenko, A.; Solovyanov, O. V.; Solovyev, V.; Sommer, P.; Song, H. Y.; Soni, N.; Sood, A.; Sopczak, A.; Sopko, B.; Sopko, V.; Sorin, V.; Sosa, D.; Sosebee, M.; Sotiropoulou, C. L.; Soualah, R.; Soukharev, A. M.; South, D.; Sowden, B. C.; Spagnolo, S.; Spalla, M.; Spangenberg, M.; Spanò, F.; Spearman, W. R.; Sperlich, D.; Spettel, F.; Spighi, R.; Spigo, G.; Spiller, L. A.; Spousta, M.; St. Denis, R. D.; Stabile, A.; Staerz, S.; Stahlman, J.; Stamen, R.; Stamm, S.; Stanecka, E.; Stanescu, C.; Stanescu-Bellu, M.; Stanitzki, M. M.; Stapnes, S.; Starchenko, E. A.; Stark, J.; Staroba, P.; Starovoitov, P.; Staszewski, R.; Steinberg, P.; Stelzer, B.; Stelzer, H. J.; Stelzer-Chilton, O.; Stenzel, H.; Stewart, G. A.; Stillings, J. A.; Stockton, M. C.; Stoebe, M.; Stoicea, G.; Stolte, P.; Stonjek, S.; Stradling, A. R.; Straessner, A.; Stramaglia, M. E.; Strandberg, J.; Strandberg, S.; Strandlie, A.; Strauss, E.; Strauss, M.; Strizenec, P.; Ströhmer, R.; Strom, D. M.; Stroynowski, R.; Strubig, A.; Stucci, S. A.; Stugu, B.; Styles, N. A.; Su, D.; Su, J.; Subramaniam, R.; Succurro, A.; Suchek, S.; Sugaya, Y.; Suk, M.; Sulin, V. V.; Sultansoy, S.; Sumida, T.; Sun, S.; Sun, X.; Sundermann, J. E.; Suruliz, K.; Susinno, G.; Sutton, M. R.; Suzuki, S.; Svatos, M.; Swiatlowski, M.; Sykora, I.; Sykora, T.; Ta, D.; Taccini, C.; Tackmann, K.; Taenzer, J.; Taffard, A.; Tafirout, R.; Taiblum, N.; Takai, H.; Takashima, R.; Takeda, H.; Takeshita, T.; Takubo, Y.; Talby, M.; Talyshev, A. A.; Tam, J. Y. C.; Tan, K. G.; Tanaka, J.; Tanaka, R.; Tanaka, S.; Tannenwald, B. B.; Tapia Araya, S.; Tapprogge, S.; Tarem, S.; Tarrade, F.; Tartarelli, G. F.; Tas, P.; Tasevsky, M.; Tashiro, T.; Tassi, E.; Tavares Delgado, A.; Tayalati, Y.; Taylor, F. E.; Taylor, G. N.; Taylor, P. T. E.; Taylor, W.; Teischinger, F. A.; Teixeira Dias Castanheira, M.; Teixeira-Dias, P.; Temming, K. K.; Temple, D.; Ten Kate, H.; Teng, P. K.; Teoh, J. J.; Tepel, F.; Terada, S.; Terashi, K.; Terron, J.; Terzo, S.; Testa, M.; Teuscher, R. J.; Theveneaux-Pelzer, T.; Thomas, J. P.; Thomas-Wilsker, J.; Thompson, E. N.; Thompson, P. D.; Thompson, R. J.; Thompson, A. S.; Thomsen, L. A.; Thomson, E.; Thomson, M.; Thun, R. P.; Tibbetts, M. J.; Ticse Torres, R. E.; Tikhomirov, V. O.; Tikhonov, Yu. A.; Timoshenko, S.; Tiouchichine, E.; Tipton, P.; Tisserant, S.; Todome, K.; Todorov, T.; Todorova-Nova, S.; Tojo, J.; Tokár, S.; Tokushuku, K.; Tollefson, K.; Tolley, E.; Tomlinson, L.; Tomoto, M.; Tompkins, L.; Toms, K.; Torrence, E.; Torres, H.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Trefzger, T.; Tremblet, L.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Tripiana, M. F.; Trischuk, W.; Trocmé, B.; Troncon, C.; Trottier-McDonald, M.; Trovatelli, M.; Truong, L.; Trzebinski, M.; Trzupek, A.; Tsarouchas, C.; Tseng, J. C-L.; Tsiareshka, P. V.; Tsionou, D.; Tsipolitis, G.; Tsirintanis, N.; Tsiskaridze, S.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsui, K. M.; Tsukerman, I. I.; Tsulaia, V.; Tsuno, S.; Tsybychev, D.; Tudorache, A.; Tudorache, V.; Tuna, A. N.; Tupputi, S. A.; Turchikhin, S.; Turecek, D.; Turra, R.; Turvey, A. J.; Tuts, P. M.; Tykhonov, A.; Tylmad, M.; Tyndel, M.; Ueda, I.; Ueno, R.; Ughetto, M.; Ukegawa, F.; Unal, G.; Undrus, A.; Unel, G.; Ungaro, F. C.; Unno, Y.; Unverdorben, C.; Urban, J.; Urquijo, P.; Urrejola, P.; Usai, G.; Usanova, A.; Vacavant, L.; Vacek, V.; Vachon, B.; Valderanis, C.; Valencic, N.; Valentinetti, S.; Valero, A.; Valery, L.; Valkar, S.; Vallecorsa, S.; Valls Ferrer, J. A.; Van Den Wollenberg, W.; Van Der Deijl, P. C.; van der Geer, R.; van der Graaf, H.; van Eldik, N.; van Gemmeren, P.; Van Nieuwkoop, J.; van Vulpen, I.; van Woerden, M. C.; Vanadia, M.; Vandelli, W.; Vanguri, R.; Vaniachine, A.; Vannucci, F.; Vardanyan, G.; Vari, R.; Varnes, E. W.; Varol, T.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vazeille, F.; Vazquez Schroeder, T.; Veatch, J.; Veloce, L. M.; Veloso, F.; Velz, T.; Veneziano, S.; Ventura, A.; Ventura, D.; Venturi, M.; Venturi, N.; Venturini, A.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, J. C.; Vest, A.; Vetterli, M. C.; Viazlo, O.; Vichou, I.; Vickey, T.; Vickey Boeriu, O. E.; Viehhauser, G. H. A.; Viel, S.; Vigne, R.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Vivarelli, I.; Vives Vaque, F.; Vlachos, S.; Vladoiu, D.; Vlasak, M.; Vogel, M.; Vokac, P.; Volpi, G.; Volpi, M.; von der Schmitt, H.; von Radziewski, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vuillermet, R.; Vukotic, I.; Vykydal, Z.; Wagner, P.; Wagner, W.; Wahlberg, H.; Wahrmund, S.; Wakabayashi, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, K.; Wang, R.; Wang, S. M.; Wang, T.; Wang, T.; Wang, X.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Washbrook, A.; Wasicki, C.; Watkins, P. M.; Watson, A. T.; Watson, I. J.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, S.; Weber, M. S.; Weber, S. W.; Webster, J. S.; Weidberg, A. R.; Weinert, B.; Weingarten, J.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M.; Werner, P.; Wessels, M.; Wetter, J.; Whalen, K.; Wharton, A. M.; White, A.; White, M. J.; White, R.; White, S.; Whiteson, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wienemann, P.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wildauer, A.; Wilkens, H. G.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, A.; Wilson, J. A.; Wingerter-Seez, I.; Winklmeier, F.; Winter, B. T.; Wittgen, M.; Wittkowski, J.; Wollstadt, S. J.; Wolter, M. W.; Wolters, H.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wozniak, K. W.; Wu, M.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xu, D.; Xu, L.; Yabsley, B.; Yacoob, S.; Yakabe, R.; Yamada, M.; Yamaguchi, D.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, S.; Yamanaka, T.; Yamauchi, K.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, Y.; Yao, W-M.; Yap, Y. C.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yeletskikh, I.; Yen, A. L.; Yildirim, E.; Yorita, K.; Yoshida, R.; Yoshihara, K.; Young, C.; Young, C. J. S.; Youssef, S.; Yu, D. R.; Yu, J.; Yu, J. M.; Yu, J.; Yuan, L.; Yuen, S. P. Y.; Yurkewicz, A.; Yusuff, I.; Zabinski, B.; Zaidan, R.; Zaitsev, A. M.; Zalieckas, J.; Zaman, A.; Zambito, S.; Zanello, L.; Zanzi, D.; Zeitnitz, C.; Zeman, M.; Zemla, A.; Zeng, Q.; Zengel, K.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zhang, D.; Zhang, F.; Zhang, G.; Zhang, H.; Zhang, J.; Zhang, L.; Zhang, R.; Zhang, X.; Zhang, Z.; Zhao, X.; Zhao, Y.; Zhao, Z.; Zhemchugov, A.; Zhong, J.; Zhou, B.; Zhou, C.; Zhou, L.; Zhou, L.; Zhou, M.; Zhou, N.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhukov, K.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, S.; Zinonos, Z.; Zinser, M.; Ziolkowski, M.; Živković, L.; Zobernig, G.; Zoccoli, A.; zur Nedden, M.; Zurzolo, G.; Zwalinski, L.

    2015-12-10

    A search for flavour-changing neutral current decays of a top quark to an uptype quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to bb¯, is presented. The analysis searches for top quark pair events in which one top quark decays to Wb, with the W boson decaying leptonically, and the other top quark decays to Hq. The search is based on pp collisions at √s = 8 TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and uses an integrated luminosity of 20.3 fb-1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon and at least four jets. The search exploits the high multiplicity of b-quark jets characteristic of signal events, and employs a likelihood discriminant that uses the kinematic differences between the signal and the background, which is dominated by tt¯→ WbWb decays. No significant excess of events above the background expectation is found, and observed (expected) 95% CL upper limits of 0.56% (0.42%) and 0.61% (0.64%) are derived for the t → Hc and t → Hu branching ratios respectively. The combination of this search with other ATLAS searches in the H → γγ and H → WW*, ττ decay modes significantly improves the sensitivity, yielding observed (expected) 95% CL upper limits on the t → Hc and t → Hu branching ratios of 0.46% (0.25%) and 0.45% (0.29%) respectively. The corresponding combined observed (expected) upper limits on the |λ tcH | and |λ tuH | couplings are 0.13 (0.10) and 0.13 (0.10) respectively. As a result, these are the most restrictive direct bounds on tqH interactions measured so far.

  16. Search for standard model production of four top quarks in the lepton + jets channel in pp collisions at ? = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2014-11-27

    A search is presented for standard model (SM) production of four top quarks (t?tt?t) in pp collisions in the lepton + jets channel. The data correspond to an integrated luminosity of 19.6? recorded at a centre-of-mass energy of 8 TeV with the CMS detector at the CERN LHC. The expected cross section for SM (t?tt?t) production is ?SM(t?tt?t). A combination of kinematic reconstruction and multivariate techniques is used to distinguish between the small signal and large background. The data are consistent with expectations of the SM, and an upper limit of 32 fb is set at a 95% confidence level on the cross section for producing four top quarks in the SM, where a limit of 32 17 fb is expected.

  17. Measurement of Spin Correlation between Top and Antitop Quarks Produced in $p\\bar{p}$ Collisions at $\\sqrt{s} = 1.96$ TeV

    SciTech Connect (OSTI)

    Abazov, Victor Mukhamedovich; et al.

    2015-12-29

    We present a measurement of the correlation between the spins of t and tbar quarks produced in proton-antiproton collisions at the Tevatron Collider at a center-of-mass energy of 1.96 TeV. We apply a matrix element technique to dilepton and single-lepton+jets final states in data accumulated with the D0 detector that correspond to an integrated luminosity of 9.7 fb$^{-1}$. The measured value of the correlation coefficient in the off-diagonal basis, $O_{off} = 0.89 \\pm 0.22$ (stat + syst), is in agreement with the standard model prediction, and represents evidence for a top-antitop quark spin correlation difference from zero at a level of 4.2 standard deviations.

  18. Search for standard model production of four top quarks in the lepton + jets channel in pp collisions at ? = 8 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2014-11-27

    A search is presented for standard model (SM) production of four top quarks (t?tt?t) in pp collisions in the lepton + jets channel. The data correspond to an integrated luminosity of 19.6? recorded at a centre-of-mass energy of 8 TeV with the CMS detector at the CERN LHC. The expected cross section for SM (t?tt?t) production is ?SM(t?tt?t). A combination of kinematic reconstruction and multivariate techniques is used to distinguish between the small signal and large background. The data are consistent with expectations of the SM, and an upper limit of 32 fb is set at a 95% confidence levelmoreon the cross section for producing four top quarks in the SM, where a limit of 32 17 fb is expected.less

  19. Top physics: search for electroweak single top quark production in p anti-p collisions at s**(1/2) = 1.96 tev

    SciTech Connect (OSTI)

    Acosta, D.; The CDF Collaboration

    2005-01-12

    We report on a search for Standard Model t-channel and s-channel single top quark production in p{bar p} collisions at a center of mass energy of 1.96 TeV. We use a data sample corresponding to 162 pb{sup -1} recorded by the upgraded Collider Detector at Fermilab. We find no significant evidence for electroweak top quark production and set upper limits at the 95% confidence level on the production cross section, consistent with the Standard Model: 10.1 pb for the t-channel, 13.6 pb for the s-channel and 17.8 pb for the combined cross section of t- and s-channel.

  20. Direct observation of quark-hadron duality in the free neutron F2 structure function

    SciTech Connect (OSTI)

    Niculescu, I.; Niculescu, G.; Melnitchouk, W.; Arrington, J.; Christy, M. E.; Ent, R.; Griffioen, K. A.; Kalantarians, N.; Keppel, C. E.; Kuhn, S.; Tkachenko, S.; Zhang, J.

    2015-05-21

    Using data from the recent BONuS experiment at Jefferson Lab, which utilized a novel spectator tagging technique to extract the inclusive electron-free neutron scattering cross section, we obtain the first direct observation of quark-hadron duality in the neutron F2 structure function. In addition, the data are used to reconstruct the lowest few (N = 2, 4 and 6) moments of F2 in the three prominent nucleon resonance regions, as well as the moments integrated over the entire resonance region. Comparison with moments computed from global parametrizations of parton distribution functions suggest that quark--hadron duality holds locally for the neutron in the second and third resonance regions down to Q2 ≈ 1 GeV2, with violations possibly up to 20% observed in the first resonance region.

  1. Search for Standard Model Production of Four Top Quarks in the Lepton + Jets Channel in pp Collisions at $\\sqrt{s}$ = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2014-09-27

    Our search is presented for standard model (SM) production of four top quarks (t¯tt¯t) in pp collisions in the lepton + jets channel. The data correspond to an integrated luminosity of 19.6 fb-1 recorded at a centre-of-mass energy of 8 TeV with the CMS detector at the CERN LHC. The expected cross section for SM t¯tt¯t production is σSMt¯tt¯t≈1fb. A combination of kinematic reconstruction and multivariate techniques is used to distinguish between the small signal and large background. We determined that the data are consistent with expectations of the SM, and an upper limit of 32 fb is set at a 95% confidence level on the cross section for producing four top quarks in the SM, where a limit of 32 ± 17 fb is expected.

  2. Search for a Dark Matter Candidate Produced in Association with a Single Top Quark in pp? Collisions at ?s=1.96 TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; lvarez Gonzlez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Anz, F.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bisello, D.; Bizjak, I.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.; Calamba, A.; Calancha, C.; Camarda, S.; Campanelli, M.; Campbell, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chung, W. H.; Chung, Y. S.; Ciocci, M. A.; Clark, A.; Clarke, C.; Compostella, G.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Crescioli, F.; Cuevas, J.; Culbertson, R.; Dagenhart, D.; dAscenzo, N.; Datta, M.; de Barbaro, P.; DellOrso, M.; Demortier, L.; Deninno, M.; Devoto, F.; dErrico, M.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; DOnofrio, M.; Donati, S.; Dong, P.; Dorigo, M.; Dorigo, T.; Ebina, K.; Elagin, A.; Eppig, A.; Erbacher, R.; Errede, S.; Ershaidat, N.; Eusebi, R.; Farrington, S.; Feindt, M.; Fernandez, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Frank, M. J.; Franklin, M.; Freeman, J. C.; Fuks, B.; Funakoshi, Y.; Furic, I.; Gallinaro, M.; Garcia, J. E.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Goldschmidt, N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; Gonzlez, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Halkiadakis, E.; Hamaguchi, A.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harr, R. F.; Hatakeyama, K.; Hays, C.; Heck, M.; Heinrich, J.; Herndon, M.; Hewamanage, S.; Hocker, A.; Hopkins, W.; Horn, D.; Hou, S.; Hughes, R. E.; Hurwitz, M.; Husemann, U.; Hussain, N.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kim, Y. J.; Kimura, N.; Kirby, M.; Klimenko, S.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kurata, M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; LeCompte, T.; Lee, E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lin, C.-J.; Lindgren, M.; Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maeshima, K.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.; Martnez, M.; Mastrandrea, P.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Mondragon, M. N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlock, J.; Movilla Fernandez, P.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Neubauer, M. S.; Nielsen, J.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagan Griso, S.; Pagliarone, C.; Palencia, E.; Papadimitriou, V.; Paramonov, A. A.; Patrick, J.; Pauletta, G.; Paulini, M.; Paus, C.; Pellett, D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Prokoshin, F.; Pranko, A.; Ptohos, F.; Punzi, G.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Renton, P.; Rescigno, M.; Riddick, T.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Safonov, A.

    2012-05-01

    We report a new search for dark matter in a data sample of an integrated luminosity of 7.7 fb? of Tevatron pp collisions at ?s=1.96 TeV, collected by the CDF II detector. We search for production of a dark-matter candidate, D, in association with a single top quark. We consider the hadronic decay mode of the top quark exclusively, yielding a final state of three jets with missing transverse energy. The data are consistent with the standard model; we thus set 95% confidence level upper limits on the cross section of the process pp??t+D as a function of the mass of the dark-matter candidate. The limits are approximately 0.5 pb for a dark-matter particle with mass in the range of 0150 GeV/c.

  3. Search for New Bottomlike Quark Pair Decays Q Q-Bar to (T W- ) (T-Bar W -) in Same-Charge Dilepton Events

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Apresyan, A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Attal, A.; Aurisano, A.; Azfar, F.; Badgett, W.; Barbaro-Galtieri, A.; Barnes, V.E.; Barnett, B.A.; /more authors..

    2012-04-02

    We report the most restrictive direct limits on masses of fourth-generation down-type quarks b{prime}, and quark-like composite fermions (B or T{sub 5/3}), decaying promptly to tW{sup {-+}}. We search for a significant excess of events with two same-charge leptons (e, {mu}), several hadronic jets, and missing transverse energy. An analysis of data from p{bar p} collisions with an integrated luminosity of 2.7 fb{sup -1} collected with the CDF II detector at Fermilab yields no evidence for such a signal, setting mass limits m{sub b{prime}}, m{sub B} > 338 GeV/c{sup 2} and m{sub T{sub 5/3}} > 365 GeV/c{sup 2} at 95% confidence level.

  4. Top Quark Mass Measurement in the Lepton + Jets Channel Using a Matrix Element Method and \\textit{in situ} Jet Energy Calibration

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2010-10-01

    A precision measurement of the top quark mass m{sub t} is obtained using a sample of t{bar t} events from p{bar p} collisions at the Fermilab Tevatron with the CDF II detector. Selected events require an electron or muon, large missing transverse energy, and exactly four high-energy jets, at least one of which is tagged as coming from a b quark. A likelihood is calculated using a matrix element method with quasi-Monte Carlo integration taking into account finite detector resolution and jet mass effects. The event likelihood is a function of m{sub t} and a parameter {Delta}{sub JES} used to calibrate the jet energy scale in situ. Using a total of 1087 events, a value of m{sub t} = 173.0 {+-} 1.2 GeV/c{sup 2} is measured.

  5. Search for Charged Strange Quark Matter Produced in 11.5{ital A} GeV/{ital c} Au+Pb Collisions

    SciTech Connect (OSTI)

    De Cataldo, G.; Giglietto, N.; Raino, A.; Spinelli, P.; Huang, H.Z.; Hill, J.C.; Hoversten, R.A.; Libby, B.; Wohn, F.K.; Rabin, M.S.; Haridas, P.; Pless, I.A.; Van Buren, G.; Armstrong, T.A.; Lewis, R.A.; Reid, J.D.; Smith, G.A.; Toothacker, W.S.; Davies, R.; Hirsch, A.S.; Porile, N.T.; Rimai, A.; Scharenberg, R.P.; Srivastava, B.K.; Tincknell, M.L.; Lainis, T.; Greene, S.V.; Bennett, S.J.; Cormier, T.M.; Dee, P.; Fachini, P.; Kim, B.; Li, Q.; Munhoz, M.G.; Pruneau, C.A.; Wilson, W.K.; Zhao, K.; Barish, K.N.; Bennett, M.J.; Chikanian, A.; Coe, S.D.; Diebold, G.E.; Finch, L.E.; George, N.K.; Kumar, B.S.; Lajoie, J.G.; Majka, R.D.; Nagle, J.L.; Pope, J.K.; Rotondo, F.S.; Sandweiss, J.; Slaughter, A.J.; Wolin, E.J.; Xu, Z.

    1997-11-01

    We present results of a search for strange quark matter (strangelets) in 11.5A GeV /c Au+Pb collisions from the 1994 and 1995 runs of experiment E864 at Brookhaven{close_quote}s Alternating Gradient Synchrotron. We observe no strangelet candidates and set a 90{percent} confidence level upper limit of approximately 3{times}10{sup {minus}8} per 10{percent} central interaction for the production of {vert_bar}Z{vert_bar}=1 and {vert_bar}Z{vert_bar}=2 strangelets over a large mass range and with metastable lifetimes of about 50ns or more. These results place constraints primarily on quark-gluon plasma based production models for strangelets. {copyright} {ital 1997} {ital The American Physical Society}

  6. Measurement of the top-quark mass in all-jets $$t\\bar{t}$$ events in pp collisions at $$\\sqrt{s}$$=7 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chatrchyan, Serguei

    2013-07-17

    The mass of the top quark is measured using a sample ofmore » $$t\\bar{t}$$ candidate events with at least six jets in the final state. The sample is selected from data collected with the CMS detector in pp collisions at $$\\sqrt{s}$$ = 7 TeV in 2011 and corresponds to an integrated luminosity of 3.54 inverse femtobarns. The mass is reconstructed for each event employing a kinematic fit of the jets to a $$t\\bar{t}$$ hypothesis. The top-quark mass is measured to be 173.49 $$\\pm$$ 0.69 (stat.) $$\\pm$$ 1.21 (syst.) GeV. A combination with previously published measurements in other decay modes by CMS yields a mass of 173.54 $$\\pm$$ 0.33 (stat.) $$\\pm$$ 0.96 (syst.) GeV.« less

  7. Search for Standard Model Production of Four Top Quarks in the Lepton + Jets Channel in pp Collisions at $$\\sqrt{s}$$ = 8 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2014-09-27

    Our search is presented for standard model (SM) production of four top quarks (t¯tt¯t) in pp collisions in the lepton + jets channel. The data correspond to an integrated luminosity of 19.6 fb-1 recorded at a centre-of-mass energy of 8 TeV with the CMS detector at the CERN LHC. The expected cross section for SM t¯tt¯t production is σSMt¯tt¯t≈1fb. A combination of kinematic reconstruction and multivariate techniques is used to distinguish between the small signal and large background. We determined that the data are consistent with expectations of the SM, and an upper limit of 32 fb is set atmore » a 95% confidence level on the cross section for producing four top quarks in the SM, where a limit of 32 ± 17 fb is expected.« less

  8. Measurement of the top quark pair production cross-section in dimuon final states in proton-antiproton collisions at 1.96 TeV

    SciTech Connect (OSTI)

    Konrath, Jens Peter; /Freiburg U.

    2008-09-01

    Particle physics deals with the fundamental building blocks of matter and their interactions. The vast number of subatomic particles can be reduced to twelve fundamental fermions, which interact by the exchange of spin-1 particles as described in the Standard Model (SM) of particle physics. The SM provides the best description of the subatomic world to date, despite the fact it does not include gravitation. Following the relation {lambda} = h/p, where h is Planck's constant, for the examination of physics at subatomic scales with size {lambda} probes with high momenta p are necessary. These high energies are accessible through particle colliders. Here, particles are accelerated and brought to collision at interaction points at which detectors are installed to record these particle collisions. Until the anticipated start-up of the Large Hadron Collider at CERN, the Tevatron collider at Fermilab near Chicago is the highest energy collider operating in the world, colliding protons and anti-protons at a center-of-mass energy of {radical}s = 1.96 TeV. Its two interaction points are covered by the multi purpose particle detectors D0 and CDF. During the first data-taking period, known as Run I, the Tevatron operated at a center-of-mass energy of 1.8 TeV. This run period lasted from 1992 to 1996. During this period, the long-predicted top quark was discovered. From 1996 and 2001, the accelerator was upgraded to deliver higher instantaneous luminosities at its current center-of-mass energy. At the same time, the experiments were upgraded to take full advantage of the upgraded accelerator complex. The Tevatron is currently the only accelerator in the world with a sufficient energy to produce top quarks. Studying top quark production, decay and properties is an important part of the D0 and CDF physics programs. Because of its large mass, the top quark is a unique probe of the Standard Model, and an interesting environment to search for new physics. In this thesis, a measurement of the production cross-section of top quark pairs decaying to two muons is presented. In addition, a Monte Carlo study of the top quark spin correlation measurement was carried out. This thesis is laid out as follows: chapter two gives a short overview over the Standard Model of particle physics and the theoretical aspects of unpolarized and polarized top quark production and decay, chapter three describes the accelerator complex and the D0 experiment whose data is used in this analysis. The Reconstruction of events recorded with the D0 detector is explained in chapter four and the data and Monte Carlo samples used are presented in chapter five. Finally, the cross-section measurement is described in chapter six and the Monte Carlo study of top quark spin correlations in chapter seven.

  9. Electroexcitation of the Δ(1232)3/2+ and Δ(1600)3/2+ in a light-front relativistic quark model

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aznauryan, Inna G.; Burkert, Volker D.

    2015-09-30

    The magnetic-dipole form factor and the ratios REM and RSM for the γ* N → Δ(1232)3/2+ transition are predicted within light-front relativistic quark model up to photon virtuality Q2=12 GeV2. Furthermore, we predict the helicity amplitudes of the γ* N → Δ(1600)3/2+ transition assuming the Δ(1600)3/2+ is the first radial excitation of the ground state Delta(1232)3/2+.

  10. A Measurement of the Top Quark Mass with the D0 Detector at s**(1/2) = 1.96-TeV using the Matrix Element Method

    SciTech Connect (OSTI)

    Kroeninger, Kevin Alexander; /Bonn U.

    2004-04-01

    Using a data set of 158 and 169 pb{sup -1} of D0 Run-II data in the electron and muon plus jets channel, respectively, the top quark mass has been measured using the Matrix Element Method. The method and its implementation are described. Its performance is studied in Monte Carlo using ensemble tests and the method is applied to the Moriond 2004 data set.

  11. Measurement of the W boson helicity in events with a single reconstructed top quark in pp collisions at $ \\sqrt{s}=8 $ TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, V.

    2015-01-12

    A measurement of the W boson helicity is presented, where the W boson originates from the decay of a top quark produced in pp collisions. The event selection, optimized for reconstructing a single top quark in the final state, requires exactly one isolated lepton (muon or electron) and exactly two jets, one of which is likely to originate from the hadronization of a bottom quark. The analysis is performed using data recorded at a center-of-mass energy of 8 TeV with the CMS detector at the CERN LHC in 2012. The data sample corresponds to an integrated luminosity of 19.7 fb$^{-1}$.moreThe measured helicity fractions are F$_{L}$ = 0.298 0.028 (stat) 0.032(syst), F$_{0}$ = 0.720 0.039 (stat) 0.037(syst), and F$_{R}$ = -0.018 0.019 (stat) 0.011(syst). These results are used to set limits on the real part of the tWb anomalous couplings, g$_{L}$ and g$_{R}$.less

  12. Measurement of the Top Quark Mass in p anti-p Collisions at s**(1/2) = 1.96-TeV using the Decay Length Technique

    SciTech Connect (OSTI)

    Abulencia, A.; Adelman, J.; Affolder, T.; Akimoto, T.; Albrow, M.G.; Ambrose, D.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; Annovi, A.; /Taiwan, Inst. Phys. /Argonne /Barcelona, IFAE /Baylor U. /INFN, Bologna /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara /Cantabria Inst. of Phys.

    2006-12-01

    We report the first measurement of the top quark mass using the decay length technique in p{bar p} collisions at a center-of-mass energy of 1.96 TeV. This technique uses the measured flight distance of the b hadron to infer the mass of the top quark in lepton plus jets events with missing transverse energy. It relies solely on tracking and avoids the jet energy scale uncertainty that is common to all other methods used so far. We apply our novel method to a 695 pb{sup -1} data sample recorded by the CDF II detector at Fermilab and extract a measurement of m{sub t} = 180.7{sub -13.4}{sup +15.5}(stat.) {+-} 8.6 (syst.) GeV/c{sup 2}. While the uncertainty of this result is larger than that of other measurements, the dominant uncertainties in the decay length technique are uncorrelated with those in other methods. This result can help reduce the overall uncertainty when combined with other existing measurements of the top quark mass.

  13. Measurement of the differential cross section for top quark pair production in pp collisions at $\\sqrt{s}$ = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-11-20

    The normalized differential cross section for top quark pair (tt¯) production is measured in pp collisions at a centre-of-mass energy of 8TeV at the CERN LHC using the CMS detector in data corresponding to an integrated luminosity of 19.7fb–1. The measurements are performed in the lepton+jets (e/μ +jets) and in the dilepton (e+e, μ+μ, and e±μ) decay channels. The tt¯ cross section is measured as a function of the kinematic properties of the charged leptons, the jets associated to b quarks, the top quarks, and the tt¯ system. The data are compared with several predictions from perturbative quantum chromodynamic up to approximate next-to-next-to-leading-order precision. Furthermore, no significant deviations are observed relative to the standard model predictions.

  14. Search for the Production of Scalar Bottom Quarks in $p \\bar {p} $ collisions at $\\sqrt{s} $ = 1.96 TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Apresyan, A.; Arisawa, T.

    2010-05-01

    We report on a search for direct scalar bottom quark (sbottom) pair production in p{bar p} collisions at {radical}s = 1.96 TeV, in events with large missing transverse energy and two jets of hadrons in the final state, where at least one of the jets is required to be identified as originating from a b quark. The study uses a CDF Run II data sample corresponding to 2.65 fb{sup -1} of integrated luminosity. The data are in agreement with the standard model. In an R-parity conserving minimal supersymmetric scenario, and assuming that the sbottom decays exclusively into a bottom quark and a neutralino, 95% confidence-level upper limits on the sbottom pair production cross section of 0.1 pb are obtained. For neutralino masses below 70 GeV/c{sup 2}, sbottom masses up to 230 GeV/c{sup 2} are excluded at 95% confidence level.

  15. Light hadron spectra in the constituent quark model with the Kobayashi-Kondo-Maskawa-'t Hooft effective U {sub A} (1) symmetry breaking interaction

    SciTech Connect (OSTI)

    Dmitrasinovic, V. . E-mail: dmitrasin@yahoo.com; Toki, H.

    2006-02-15

    We make a critical comparison of several versions of instanton-induced interactions present in the literature, all based on ITEP group's extension to three colours and flavours of 't Hooft's effective lagrangian, with the predictions of the phenomenological Kobayashi-Kondo-Maskawa (KKM) chiral quark lagrangian. We analyze the effects of all versions of the effective U {sub A} (1) symmetry breaking interactions on light hadron spectra in the non-relativistic constituent quark model. We show that the KKMT force, when used as a residual hyperfine interaction reproduces the correct ordering of pseudoscalar and vector mesons even without explicitly taking chiral symmetry into account. Moreover, the nucleon spectra are also correctly reproduced, only the Roper resonance remains too high, albeit lower than usual, at 1660 MeV. The latter's lower than expected mass is not due to a small excitation energy, as in the Glozman-Riska (GR) model, but to a combination of colour, flavour, and spatial wave function properties that enhance the relevant matrix elements. The KKMT interaction explicitly depends on flavour and spin of the quarks, but unlike the GR flavour-spin one it has a firm footing in QCD. In the process we provide several technical advances, in particular we show the first explicit derivation of the three-body Fierz transformation and apply it to the KKM interaction. We also discuss the ambiguities associated with the colour degree of freedom.

  16. Search for charged Higgs bosons in decays of top quarks in proton - antiproton collisions at s**(1/2) = 1.96 TeV

    SciTech Connect (OSTI)

    Yu, Geum Bong; /Rochester U.

    2009-08-01

    In this dissertation we report on the first direct search for charged Higgs bosons in decays of top quarks in p{bar p} collisions at {radical}s = 1.96 TeV. The search uses a data sample with an integrated luminosity of 2.2 fb{sup -1} collected by the CDF II detector at Fermilab and looks for a resonance in the invariant mass distribution of two jets in the lepton+jets sample of t{bar t} candidates. We observe no evidence of charged Higgs bosons in top quark decays; hence 95% C.L. upper limits on the branching ratio are placed at {Beta}(t {yields} H{sup +}b) < 0.1 to 0.3 for charged Higgs boson masses of 60 to 150 GeV/c{sup 2} assuming {Beta}(H{sup +} {yields} c{bar s}) = 1.0 and {Beta}(t {yields} Wb)+{Beta}(t {yields} H{sup +}b) = 1.0. The upper limits on {Beta}(t {yields} H{sup +}b) are also used as model independent limits on the decay branching ratio of top quarks to any charged scalar bosons beyond the standard model.

  17. Measurement of the top quark mass at CDF using the `neutrino phi weighting' template method on a lepton plus isolated track sample

    SciTech Connect (OSTI)

    Aaltonen, T.; Adelman, J.; Akimoto, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Apresyan, A.; /Purdue U. /Waseda U.

    2009-01-01

    We present a measurement of the top quark mass with t{bar t} dilepton events produced in p{bar p} collisions at the Fermilab Tevatron ({radical}s = 1.96 TeV) and collected by the CDF II detector. A sample of 328 events with a charged electron or muon and an isolated track, corresponding to an integrated luminosity of 2.9 fb{sup -1}, are selected as t{bar t} candidates. To account for the unconstrained event kinematics, we scan over the phase space of the azimuthal angles ({phi}{sub {nu}1}, {phi}{sub {nu}2}) of neutrinos and reconstruct the top quark mass for each {phi}{sub {nu}1}, {phi}{sub {nu}2} pair by minimizing a {chi}{sup 2} function in the t{bar t} dilepton hypothesis. We assign {chi}{sup 2}-dependent weights to the solutions in order to build a preferred mass for each event. Preferred mass distributions (templates) are built from simulated t{bar t} and background events, and parameterized in order to provide continuous probability density functions. A likelihood fit to the mass distribution in data as a weighted sum of signal and background probability density functions gives a top quark mass of 165.5{sub -3.3}{sup +3.4}(stat.){+-}3.1(syst.) GeV/c{sup 2}.

  18. Measurement of the W boson helicity in events with a single reconstructed top quark in pp collisions at $ \\sqrt{s}=8 $ TeV

    SciTech Connect (OSTI)

    Khachatryan, V.

    2015-01-12

    A measurement of the W boson helicity is presented, where the W boson originates from the decay of a top quark produced in pp collisions. The event selection, optimized for reconstructing a single top quark in the final state, requires exactly one isolated lepton (muon or electron) and exactly two jets, one of which is likely to originate from the hadronization of a bottom quark. The analysis is performed using data recorded at a center-of-mass energy of 8 TeV with the CMS detector at the CERN LHC in 2012. The data sample corresponds to an integrated luminosity of 19.7 fb$^{-1}$. The measured helicity fractions are F$_{L}$ = 0.298 0.028 (stat) 0.032(syst), F$_{0}$ = 0.720 0.039 (stat) 0.037(syst), and F$_{R}$ = -0.018 0.019 (stat) 0.011(syst). These results are used to set limits on the real part of the tWb anomalous couplings, g$_{L}$ and g$_{R}$.

  19. Measurement of the W boson helicity in events with a single reconstructed top quark in pp collisions at $$ \\sqrt{s}=8 $$ TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2015-01-12

    We presented a measurement of the W boson helicity, where the W boson originates from the decay of a top quark produced in pp collisions. The event selection, optimized for reconstructing a single top quark in the final state, requires exactly one isolated lepton (muon or electron) and exactly two jets, one of which is likely to originate from the hadronization of a bottom quark. The analysis is performed using data recorded at a center-of-mass energy of 8 TeV with the CMS detector at the CERN LHC in 2012. We also found that the data sample corresponds to an integratedmore » luminosity of 19.7 fb-1. The measured helicity fractions are F L = 0.298 ± 0.028 (stat) ± 0.032(syst), F 0 = 0.720 ± 0.039 (stat) ± 0.037(syst), and F R = -0.018 ± 0.019 (stat) ± 0.011(syst). These results are used to set limits on the real part of the tWb anomalous couplings, g L and g R.« less

  20. Logarithmic correction in the deformed AdS{sub 5} model to produce the heavy quark potential and QCD beta function

    SciTech Connect (OSTI)

    He Song; Huang Mei; Yan Qishu

    2011-02-15

    We study the holographic QCD model, which contains a quadratic term -{sigma}z{sup 2} and a logarithmic term -c{sub 0}log[(z{sub IR}-z)/z{sub IR}] with an explicit infrared cutoff z{sub IR} in the deformed AdS{sub 5} warp factor. We investigate the heavy-quark potential for three cases, i.e., with only a quadratic correction, with both quadratic and logarithmic corrections, and with only a logarithmic correction. We solve the dilaton field and dilation potential from the Einstein equation and investigate the corresponding beta function in the Guersoy-Kiritsis-Nitti framework. Our studies show that in the case with only a quadratic correction, a negative {sigma} or the Andreev-Zakharov model is favored to fit the heavy-quark potential and to produce the QCD beta function at 2-loop level; however, the dilaton potential is unbounded in the infrared regime. One interesting observation for the case of positive {sigma} is that the corresponding beta function exists in an infrared fixed point. In the case with only a logarithmic correction, the heavy-quark Cornell potential can be fitted very well, the corresponding beta function agrees with the QCD beta function at 2-loop level reasonably well, and the dilaton potential is bounded from below in the infrared. At the end, we propose a more compact model which has only a logarithmic correction in the deformed warp factor and has less free parameters.

  1. Electrical conductivity of the quark-gluon plasma and soft photon spectrum in heavy-ion collisions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yin, Yi

    2014-10-06

    We extract the electrical conductivity σ0 of the quark gluon plasma (QGP) and study the effects of magnetic field and chiral anomaly on soft photon azimuthal anisotropy, v₂, based on the thermal photon spectrum at 0.4GeV < p⊥< 0.6GeV at the RHIC energy. As a basis for my analysis, we derive the behavior of retarded photon self-energy of a strongly interacting neutral plasma in hydrodynamic regime in the presence of magnetic field and chiral anomaly. By evolving the resulting soft thermal photon production rate over the realistic hydrodynamic background and comparing the results with the data from the PHENIX Collaboration,more » I found that the electrical conductivity at QGP temperature is in the range: 0.4 < σ₀/(e²T) < 1.1, which is comparable with recent studies on lattice. I also compare the contribution from the magnetic field and chiral anomaly to soft thermal photon v₂ with the data. I argue that at the CERN Large Hadron Collider, the chiral magnetic wave would give negative contribution to photon v₂.« less

  2. Electrical conductivity of the quark-gluon plasma and soft photon spectrum in heavy-ion collisions

    SciTech Connect (OSTI)

    Yin, Yi

    2014-10-06

    We extract the electrical conductivity ?0 of the quark gluon plasma (QGP) and study the effects of magnetic field and chiral anomaly on soft photon azimuthal anisotropy, v?, based on the thermal photon spectrum at 0.4GeV < p?< 0.6GeV at the RHIC energy. As a basis for my analysis, we derive the behavior of retarded photon self-energy of a strongly interacting neutral plasma in hydrodynamic regime in the presence of magnetic field and chiral anomaly. By evolving the resulting soft thermal photon production rate over the realistic hydrodynamic background and comparing the results with the data from the PHENIX Collaboration, I found that the electrical conductivity at QGP temperature is in the range: 0.4 < ??/(eT) < 1.1, which is comparable with recent studies on lattice. I also compare the contribution from the magnetic field and chiral anomaly to soft thermal photon v? with the data. I argue that at the CERN Large Hadron Collider, the chiral magnetic wave would give negative contribution to photon v?.

  3. Measurement of the polarized forward-backward asymmetry of B quarks using momentum-weighted track charge at SLD

    SciTech Connect (OSTI)

    Junk, T.R.

    1995-11-01

    This thesis presents a direct measurement of the parity-violating parameter A{sub b} by analyzing the polarized forward-backward asymmetry of b quarks in e{sup +}e{sup {minus}} {yields} Z{sup 0} {yields} b{bar b}. Data were taken at the Stanford Linear Accelerator Center (SLAC), with the Stanford Large Detector (SLD), which records the products of e{sup +}e{sup {minus}} interactions at a center of mass energy {radical}s = 91.2 GeV/c{sup 2} at the SLAC Linear Collider (SLC). The SLC/SLD experimental apparatus provides a unique and ideal environment for measuring electroweak asymmetries. Heavy flavor decays of the Z{sup 0} were identified inclusively by taking advantage of the long lifetime of B hadrons, the small, stable SLC beam spot, and SLD`s precise tracking detectors. Two analysis techniques for measuring A{sub b} are presented: a binned fit to the left-right forward-backwards asymmetry of tagged events signed with momentum-weighted track charge, and a self-calibrating maximum-likelihood technique using momentum-weighted charge from the two hemispheres in each tagged event. From our 1994-1995 sample of 3.6 pb{sup {minus}1}, having a luminosity-weighted average e{sup {minus}} polarization of 77.3%, and our 1993 sample of 1.8 pb{sup {minus}1}, having a luminosity-weighted polarization of 63.1%, we obtain A{sub b} = 0.848 {plus_minus} 0.046(stat.) {plus_minus} 0.050(syst.).

  4. Search for invisible particles produced in association with single-top-quarks in proton–proton collisions at √s = 8 TeV with the ATLAS detector

    SciTech Connect (OSTI)

    Aad, G.

    2015-02-18

    A search for the production of single-top-quarks in association with missing energy is performed in proton–proton collisions at a centre-of-mass energy of √s=8 TeV with the ATLAS experiment at the large hadron collider using data collected in 2012, corresponding to an integrated luminosity of 20.3 fb-1. In this study, the W boson from the top quark is required to decay into an electron or a muon and a neutrino. No deviation from the standard model prediction is observed, and upper limits are set on the production cross-section for resonant and non-resonant production of an invisible exotic state in association with a right-handed top quark. In the case of resonant production, for a spin-0 resonance with a mass of 500 GeV, an effective coupling strength above 0.15 is excluded at 95% confidence level for the top quark and an invisible spin-1/2 state with mass between 0 and 100 GeV. In the case of non-resonant production, an effective coupling strength above 0.2 is excluded at 95% confidence level for the top quark and an invisible spin-1 state with mass between 0 and 657 GeV.

  5. Search for invisible particles produced in association with single-top-quarks in proton–proton collisions at √s = 8 TeV with the ATLAS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.

    2015-02-18

    A search for the production of single-top-quarks in association with missing energy is performed in proton–proton collisions at a centre-of-mass energy of √s=8 TeV with the ATLAS experiment at the large hadron collider using data collected in 2012, corresponding to an integrated luminosity of 20.3 fb-1. In this study, the W boson from the top quark is required to decay into an electron or a muon and a neutrino. No deviation from the standard model prediction is observed, and upper limits are set on the production cross-section for resonant and non-resonant production of an invisible exotic state in association withmore » a right-handed top quark. In the case of resonant production, for a spin-0 resonance with a mass of 500 GeV, an effective coupling strength above 0.15 is excluded at 95% confidence level for the top quark and an invisible spin-1/2 state with mass between 0 and 100 GeV. In the case of non-resonant production, an effective coupling strength above 0.2 is excluded at 95% confidence level for the top quark and an invisible spin-1 state with mass between 0 and 657 GeV.« less

  6. Measurement of the production cross-section of a single top quark in association with a W boson at 8 TeV with the ATLAS experiment

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; et al

    2016-01-11

    The cross-section for the production of a single top quark in association with a W boson in proton-proton collisions at √s = 8 is measured. The dataset corresponds to an integrated luminosity of 20.3 fb-1, collected by the ATLAS detector in 2012 at the Large Hadron Collider at CERN. Events containing two leptons and one central b-jet are selected. The Wt signal is separated from the backgrounds using boosted decision trees, each of which combines a number of discriminating variables into one classifier. Production of Wt events is observed with a significance of 7.7σ. The cross-section is extracted in amore » profile likelihood fit to the classifier output distributions. The Wt cross-section, inclusive of decay modes, is measured to be 23.0±1.3(stat.)-3.5+3.2(syst.)±1.1(lumi.) pb. The measured cross-section is used to extract a value for the CKM matrix element |Vtb| of 1.01 ± 0.10 and a lower limit of 0.80 at the 95% confidence level. Furthermore, the cross-section for the production of a top quark and a W boson is also measured in a fiducial acceptance requiring two leptons with p T > 25 GeV and |η| < 2.5, one jet with pT > 20 GeV and |η| < 2.5, and ETmiss >20 GeV, including both Wt and top-quark pair events as signal. The measured value of the fiducial cross-section is 0.85 ± 0.01(stat.) -0.07 +0.06 (syst.)±0.03(lumi.) pb.« less

  7. Search for Scalar Top Quark Pair-Production in Scenario with Violated R-parity in ppbar Collisions at sqrt(s)=1.96 TeV

    SciTech Connect (OSTI)

    Ogawa, Takashi

    2005-01-01

    A search for the pair production of supersymmetric partner of the top quark in scenario with R-parity violation is presented. The quantum number called R-parity distinguishes particles in standard model from supersymmetric particles. A scalar top quark (stop) is assumed to decay only via R{sub p}-violating supersymmetric coupling into tau lepton and b-quark. To collect events with multiple taus, a new special tau trigger (the lepton plus track trigger) is installed in Run II experiment of the Collider Detector at Fermilab (CDF). The goal of the lepton plus track trigger is to collect generic dilepton ({ell}{ell}, {ell}{tau}, {tau}{tau}) events with lower p{sub T} threshold (8 GeV/c) and without prescale even at high luminosity. The Z {yields} {tau}{tau} event, where one {tau}-lepton decays leptonically and the other hadronically, is a good benchmark to calibrate the lepton plus track trigger and {tau} identification. The data sample of 72 pb{sup -1}, collected using the electron plus track trigger, contains clear a {tau} signal from Z {yields} {tau}{tau} events. The data used in stop search correspond to 200 pb{sup -1}. The lower stop mass bound of 134 GeV/c{sup 2} at a 95% confidence level is obtained. This limit is also directly applicable to the case of the third generation scalar leptoquark (LQ{sub 3}) assuming a 100% branching for the LQ{sub 3} {yields} {tau}b decay mode.

  8. Search for vectorlike B quarks in events with one isolated lepton, missing transverse momentum, and jets at √s = 8 TeV with the ATLAS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; et al

    2015-06-19

    A search has been performed for pair production of heavy vectorlike down-type (B) quarks. The analysis explores the lepton-plus-jets final state, characterized by events with one isolated charged lepton (electron or muon), significant missing transverse momentum, and multiple jets. One or more jets are required to be tagged as arising from b quarks, and at least one pair of jets must be tagged as arising from the hadronic decay of an electroweak boson. The analysis uses the full data sample of pp collisions recorded in 2012 by the ATLAS detector at the LHC, operating at a center-of-mass energy of 8more » TeV, corresponding to an integrated luminosity of 20.3 fb⁻¹. No significant excess of events is observed above the expected background. Limits are set on vectorlike B production, as a function of the B branching ratios, assuming the allowable decay modes are B → Wt/Zb/Hb. In the chiral limit with a branching ratio of 100% for the decay B → Wt, the observed (expected) 95% C.L. lower limit on the vectorlike B mass is 810 GeV (760 GeV). In the case where the vectorlike B quark has branching ratio values corresponding to those of an SU(2) singlet state, the observed (expected) 95% C.L. lower limit on the vectorlike B mass is 640 GeV (505 GeV). The same analysis, when used to investigate pair production of a colored, charge 5/3 exotic fermion T5/3, with subsequent decay T5/3 → Wt, sets an observed (expected) 95% C.L. lower limit on the T5/3 mass of 840 GeV (780 GeV).« less

  9. Erratum to: Constraining couplings of top quarks to the Z boson in $$ t\\overline{t} $$ + Z production at the LHC

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Röntsch, Raoul; Schulze, Markus

    2015-09-21

    We study top quark pair production in association with a Z boson at the Large Hadron Collider (LHC) and investigate the prospects of measuring the couplings of top quarks to the Z boson. To date these couplings have not been constrained in direct measurements. Such a determination will be possible for the first time at the LHC. Our calculation improves previous coupling studies through the inclusion of next-to-leading order (NLO) QCD corrections in production and decays of all unstable particles. We treat top quarks in the narrow-width approximation and retain all NLO spin correlations. To determine the sensitivity of amore » coupling measurement we perform a binned log-likelihood ratio test based on normalization and shape information of the angle between the leptons from the Z boson decay. The obtained limits account for statistical uncertainties as well as leading theoretical systematics from residual scale dependence and parton distribution functions. We use current CMS data to place the first direct constraints on the ttbZ couplings. We also consider the upcoming high-energy LHC run and find that with 300 inverse fb of data at an energy of 13 TeV the vector and axial ttbZ couplings can be constrained at the 95% confidence level to C_V=0.24^{+0.39}_{-0.85} and C_A=-0.60^{+0.14}_{-0.18}, where the central values are the Standard Model predictions. This is a reduction of uncertainties by 25% and 42%, respectively, compared to an analysis based on leading-order predictions. We also translate these results into limits on dimension-six operators contributing to the ttbZ interactions beyond the Standard Model.« less

  10. Search for the single top quarks produced in s-channel via electroweak interactions at s = 1-96 at the Tevatron

    SciTech Connect (OSTI)

    Jabeen, Shabnam; /Kansas U.

    2006-01-01

    The authors present a search for single top quarks produced in the s-channel electroweak production mode. The search is performed in the electron+jets decay channels, with one or more secondary-vertex tagged jets to indicate the presence of a b-jet and hence improving the signal:background ratio. Separation between signal and background is further enhanced by the use of Feed Forward Neural networks. 360 pb{sup -1} of Run II data used for this analysis was delivered by the Tevatron, and collected by D0 between August 2002 and August 2004. The resulting 95% confidence level upper limit is 4 pb.

  11. Measurement of the top quark pair production cross section in proton-proton collisions at $\\sqrt{s}=13$ TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-10-18

    The top quark pair production cross section is measured for the first time in proton-proton collisions at √s= 13 TeV by theCMS experiment at the CERN LHC, using data corresponding to an integrated luminosity of 42 pb-1. The measurement is performed by analyzing events with at least one electron and one muon of opposite charge, and at least two jets. We then measured the cross section and found that was 769 ± 60 (stat) ± 55 (syst) ± 92 (lumi) pb, in agreement with the expectation from the standard model.

  12. CP violating anomalous top-quark coupling in p$\\bar{p}$ collision at $\\sqrt{s}=1.96$ TeV

    SciTech Connect (OSTI)

    Lee, Sehwook; /Iowa State U.

    2011-04-01

    We conduct the first study of the T-odd correlations in tt events produced in p{bar p} collision at the Fermilab Tevatron collider that can be used to search for CP violation. We select events which have lepton+jets final states to identify t{bar t} events and measure counting asymmetries of several physics observables. Based on the result, we search the top quark anomalous couplings at the production vertex at the Tevatron. In addition, Geant4 development, photon identification, the discrimination of a single photon and a photon doublet from {pi}{sup 0} decay are discussed in this thesis.

  13. Elliptic flow of thermal photons and formation time of quark gluon plasma at energies available at the BNL Relativistic Heavy Ion Collider (RHIC)

    SciTech Connect (OSTI)

    Chatterjee, Rupa; Srivastava, Dinesh K.

    2009-02-15

    We calculate the elliptic flow of thermal photons from Au+Au collisions at RHIC energies for a range of values for the formation time {tau}{sub 0} but a fixed entropy (or particle rapidity density). The results are found to be quite sensitive to {tau}{sub 0}. The value of v{sub 2} for photons decreases as {tau}{sub 0} decreases and admits a larger contribution from the quark gluon plasma phase, which has a smaller v{sub 2}. The elliptic flow coefficient for hadrons, however, is only marginally dependent on {tau}{sub 0}.

  14. Dynamical heavy-quark recombination and the nonphotonic single-electron puzzle at energies available at the BNL Relativistic Heavy Ion Collider (RHIC)

    SciTech Connect (OSTI)

    Ayala, Alejandro; Magnin, J.; Montano, Luis Manuel; Sanchez, G. Toledo

    2009-12-15

    We show that the single, nonphotonic electron nuclear modification factor R{sub AA}{sup e} is affected by the thermal enhancement of the heavy-baryon-to-heavy-meson ratio in relativistic heavy-ion collisions with respect to proton-proton collisions. We make use of the dynamical quark recombination model to compute such a ratio and show that this produces a sizable suppression factor for R{sub AA}{sup e} at intermediate transverse momenta. We argue that this suppression factor needs to be considered, in addition to the energy loss contribution, in calculations of R{sub AA}{sup e}.

  15. Model-independent measurement of t-channel single top quark production in p(p)over-bar collisions at,root s=1.96 TeV

    SciTech Connect (OSTI)

    Abazov, V.M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G. A.; Ancu, L. S.; Aoki, M.; Arov, M.; Askew, A.; Asman, B.; Atramentov, O.; Avila, C.; BackusMayes, J.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, R.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Beale, S.; Bean, A.; Begalli, M.; Begel, M.; Belanger-Champagne, C.; Bellantoni, L.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besancon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; Boos, E. E.; Borissov, G.; Bose, T.; Brandt, A.; Brandt, O.; Brock, R.; Brooijmans, G.; Bross, A.; Brown, D.; Brown, J.; Bu, X. B.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Burnett, T. H.; Buszello, C. P.; Calpas, B.; Camacho-Perez, E.; Carrasco-Lizarraga, M. A.; Casey, B. C. K.; Castilla-Valdez, H.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chen, G.; Chevalier-Thery, S.; Cho, D. K.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cochran, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M. -C.; Croc, A.; Cutts, D.; Das, A.; Davies, G.; De, K.; de Jong, S. J.; De La Cruz-Burelo, E.; Deliot, F.; Demarteau, M.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Dominguez, A.; Dorland, T.; Dubey, A.; Dudko, L. V.; Duggan, D.; Duperrin, A.; Dutt, S.; Dyshkant, A.; Eads, M.; Edmunds, D.; Eller, P.; Ellison, J.; Elvira, V. D.; Enari, Y.; Evans, H.; Evdokimov, A.; Evdokimov, V. N.; Facini, G.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Focke, C.; Fortner, M.; Fox, H.; Fuess, S.; Garcia-Bellido, A.; Gavrilov, V.; Gay, P.; Geng, W.; Gerbaudo, D.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Golovanov, G.; Goussiou, A.; Grannis, P. D.; Greder, S.; Greenlee, H.; Greenwood, Z. D.; Gregores, E. M.; Grenier, G.; Gris, Ph.; Grivaz, J. -F.; Grohsjean, A.; Gruenendahl, S.; Gruenewald, M. W.; Guillemin, T.; Guo, F.; Gutierrez, G.; Gutierrez, P.; Haas, A.; Hagopian, S.; Haley, J.; Han, L.; Harder, K.; Harel, A.; Hauptman, J. M.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hoeneisen, B.; Hohlfeld, M.; Hubacek, Z.; Huske, N.; Hynek, V.; Iashvili, I.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffre, M.; Jamin, D.; Jayasinghe, A.; Jesik, R.; Johns, K.; Johnson, M.; Johnston, D.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; Juste, A.; Kaadze, K.; Kajfasz, E.; Karmanov, D.; Kasper, P. A.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Khatidze, D.; Kirby, M. H.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kulikov, S.; Kumar, A.; Kupco, A.; Kurca, T.; Kuzmin, V. A.; Kvita, J.; Lammers, S.; Landsberg, G.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lellouch, J.; Li, L.; Li, Q. Z.; Lietti, S. M.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, Y.; Liu, Z.; Lobodenko, A.; Lokajicek, M.; de Sa, R. Lopes; Lubatti, H. J.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Mackin, D.; Madar, R.; Magana-Villalba, R.; Malik, S.; Malyshev, V. L.; Maravin, Y.; Martinez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; et al.

    2011-11-17

    We present a model-independent measurement of t-channel electroweak production of single top quarks in p{bar p} collisions at {radical}s = 1.96 TeV. Using 5.4 fb{sup -1} of integrated luminosity collected by the D0 detector at the Fermilab Tevatron Collider, and selecting events containing an isolated electron or muon, missing transverse energy and one or two jets originating from the fragmentation of b quarks, we measure a cross section {sigma}(p{bar p} {yields} tqb + X) = 2.90 {+-} 0.59 (stat + syst) pb for a top quark mass of 172.5 GeV. The probability of the background to fluctuate and produce a signal as large as the one observed is 1.6 x 10{sup -8}, corresponding to a significance of 5.5 standard deviations.

  16. Evidence for a particle produced in association with weak bosons and decaying to a bottom-antibottom quark pair in Higgs boson searches at the Tevatron

    SciTech Connect (OSTI)

    Aaltonen, T.; Abazov, V.M.; Abbott, B.; Acharya, B.S.; Adams, M.; Adams, T.; Alexeev, G.D.; Alkhazov, G.; Alton, A.; Alvarez Gonzalez, B.; Alverson, G.; /Northeastern U. /INFN, Padua

    2012-07-01

    We combine searches by the CDF and D0 Collaborations for the associated production of a Higgs boson with a W or Z boson and subsequent decay of the Higgs boson to a bottom-antibottom quark pair. The data, originating from Fermilab Tevatron p{bar p} collisions at {radical}s=1.96 TeV, correspond to integrated luminosities of up to 9.7 fb{sup -1}. The searches are conducted for a Higgs boson with mass in the range 100-150 GeV/c{sup 2}. We observe an excess of events in the data compared with the background predictions, which is most significant in the mass range between 120 and 135 GeV/c{sup 2}. The largest local significance is 3.3 standard deviations, corresponding to a global significance of 3.1 standard deviations. We interpret this as evidence for the presence of a new particle consistent with the standard model Higgs boson, which is produced in association with a weak vector boson and decays to a bottom-antibottom quark pair.

  17. Measurement of the top-quark mass in all-hadronic decays in p anti-p collisions at CDF II

    SciTech Connect (OSTI)

    Aaltonen, T.; Abulencia, A.; Adelman, J.; Affolder, T.; Akimoto, T.; Albrow, M.G.; Ambrose, D.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; /Fermilab /Frascati

    2006-12-01

    We present a measurement of the top-quark mass, M{sub tpo}, in the all-hadronic decay channel t{bar t} {yields} W{sup +}bW{sup -}{bar b} {yields} q{sub 1}{bar q}{sub 2}bq{sub 3}{bar q}{sub 4}{bar b}. The analysis is performed using 310 pb{sup -1} of {radical}s = 1.96 TeV p{bar p} collisions collected with the CDF II detector using a multi-jet trigger. The mass measurement is based on an event-by-event likelihood which depends on both the sample purity and the value of the top-quark mass, using 90 possible jet-to-parton assignments in the six-jet final state. The joint likelihood of 290 selected events yields a value of M{sub top} = 177.1 {+-} 4.9(stat.) {+-} 4.7(syst.) GeV/c{sup 2}.

  18. Tevatron combination of single-top-quark cross sections and determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $\\bf V_{tb}$

    SciTech Connect (OSTI)

    Aaltonen, Timo Antero

    2015-10-07

    In this study, we present the final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb-1 per experiment. The t-channel cross section is measured to be σt= 2.25-0.31+0.29 pb. We also present the combinations of the two-dimensional measurements of the s- vs t-channel cross section. In addition, we give the combination of the s+t channel cross section measurement resulting in σs+t= 3.30-0.40+0.52 pb, without assuming the standard model value for the ratio σst. The resulting value of the magnitude of the top-to-bottom quark coupling is |Vtb|= 1.02-0.05+0.06, corresponding to |Vtb| > 0.92 at the 95% C.L.

  19. Tevatron combination of single-top-quark cross sections and determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $$\\bf V_{tb}$$

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, Timo Antero; Helsinki Institute of Physics, Helsinki

    2015-10-07

    In this study, we present the final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb-1 per experiment. The t-channel cross section is measured to be σt= 2.25-0.31+0.29 pb. We also present the combinations of the two-dimensional measurements of the s- vs t-channel cross section. In addition, we give the combination of the s+t channel cross section measurement resulting in σs+t= 3.30-0.40+0.52 pb, without assuming the standard model value for the ratio σs/σt. The resulting valuemore » of the magnitude of the top-to-bottom quark coupling is |Vtb|= 1.02-0.05+0.06, corresponding to |Vtb| > 0.92 at the 95% C.L.« less

  20. A Measurement of the Top Quark Mass in 1.96 TeV Proton-Antiproton Collisions Using a Novel Matrix Element Method

    SciTech Connect (OSTI)

    CDF Collaboration; Freeman, John; Freeman, John

    2007-09-30

    A measurement of the top quark mass in t{bar t} {yields} l + jets candidate events, obtained from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector, is presented. The measurement approach is that of a matrix element method. For each candidate event, a two dimensional likelihood is calculated in the top pole mass and a constant scale factor, 'JES', where JES multiplies the input particle jet momenta and is designed to account for the systematic uncertainty of the jet momentum reconstruction. As with all matrix element techniques, the method involves an integration using the Standard Model matrix element for t{bar t} production and decay. However, the technique presented is unique in that the matrix element is modified to compensate for kinematic assumptions which are made to reduce computation time. Background events are dealt with through use of an event observable which distinguishes signal from background, as well as through a cut on the value of an event's maximum likelihood. Results are based on a 955 pb{sup -1} data sample, using events with a high-p{sub T} lepton and exactly four high-energy jets, at least one of which is tagged as coming from a b quark; 149 events pass all the selection requirements. They find M{sub meas} = 169.8 {+-} 2.3(stat.) {+-} 1.4(syst.) GeV/c{sup 2}.

  1. Search for the associated production of a Higgs boson with a single top quark in proton-proton collisions at √(s) = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-09-29

    Our paper presents the search for the production of a Higgs boson in association with a single top quark, using data collected in proton-proton collisions at a centerof-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb-1. The search exploits a variety of Higgs boson decay modes resulting in final states with photons, bottom quarks, and multiple charged leptons, including tau leptons, and employs a variety of multivariate techniques to maximize sensitivity to the signal. Furthermore, our analysis is optimized for the opposite sign of the Yukawa coupling to that in the standard model and corresponding to a large enhancement of the signal cross section. In the absence of an excess of candidate signal events over the background predictions, 95% confidence level observed (expected) upper limits on anomalous tHq production are set, ranging between 600 (450) fb and 1000 (700) fb depending on the assumed diphoton branching fraction of the Higgs boson. This is the first time that results on anomalous tHq production have been reported.

  2. Measurement of Spin Correlation in Top-Antitop Quark Events and Search for Top Squark Pair Production in pp Collisions at s=8  TeV Using the ATLAS Detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; et al

    2015-04-08

    We present a measurement of spin correlation in t¯t production using data collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb₋1. The correlation between the top and antitop quark spins is extracted from dilepton t¯t events by using the difference in the azimuthal angle between the two charged leptons in the laboratory frame. In the helicity basis the measured degree of correlation corresponds to Ahelicity = 0.38±0.04, in agreement with the standard model prediction. A search is performed for pair productionmore » of top squarks with masses close to the top quark mass decaying to predominantly right-handed top quarks and a light neutralino, the lightest supersymmetric particle. Lastly, top squarks with masses between the top quark mass and 191 GeV are excluded at the 95% confidence level.« less

  3. Measurement of the Single Top Quark Cross Section in the Lepton Plus Jets Final State in Proton-Antiproton Collisions at a Center of Mass Energy of 1.96 TeV Using the CDF II Detector

    SciTech Connect (OSTI)

    Wu, Zhenbin

    2012-01-01

    We present a measurement of the single top quark cross section in the lepton plus jets final state using an integrated luminosity corresponding to 7.5~\\text{fb}^{-1} of p\\bar p collision data collected by the Collider Detector at Fermilab. The single top candidate events are identified by the signature of a charged lepton, large missing transverse energy, and two or three jets with at least one of them identified as originating from a bottom quark. A new Monte Carlo generator \\textsc{powheg} is used to model the single top quark production processes, which include {s}-channel, {t}-channel, and {Wt}-channel. A neural network multivariate method is exploited to discriminate the single top quark signal from the comparatively large backgrounds. We measure a single top production cross section of $3.04^{+0.57}_{-0.53}$ (\\mathrm{stat.~+~syst.}) pb assuming $m_{\\rm top}=172.5$~GeV/$c^2$. In addition, we extract the CKM matrix element value $|V_{tb}|=0.96\\pm 0.09~(\\mathrm{stat.~+~syst.})\\pm 0.05~(\\mathrm{theory})$ and set a lower limit of |V_{tb}|>0.78 at the 95\\% credibility level.

  4. Measurement of Spin Correlation in Top-Antitop Quark Events and Search for Top Squark Pair Production in p p Collisions at s = 8 TeV Using the ATLAS Detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; et al

    2015-04-08

    A measurement of spin correlation in tt¯ production is presented using data collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb⁻¹. The correlation between the top and antitop quark spins is extracted from dilepton tt¯ events by using the difference in the azimuthal angle between the two charged leptons in the laboratory frame. In the helicity basis the measured degree of correlation corresponds to Ahelicity=0.38±0.04, in agreement with the standard model prediction. A search is performed for pair production of topmore » squarks with masses close to the top quark mass decaying to predominantly right-handed top quarks and a light neutralino, the lightest supersymmetric particle. Top squarks with masses between the top quark mass and 191 GeV are excluded at the 95% confidence level.« less

  5. Mesure de la section efficace de production de paires de quarks top dans l'etat final di-electron avec les donnees collectees par l'experience D0 au RunIIa

    SciTech Connect (OSTI)

    Martin Dit Latour, Bertrand; /LPSC, Grenoble

    2008-09-01

    The top quark has been discovered in 1995 by CDF and D0 collaborations in proton-antiproton collisions at the Tevatron. The amount of data recorded by both experiments makes it possible to accurately measure the properties of this very massive quark. This thesis is devoted to the measurement of the top pair production cross-section via the strong interaction, in a final state composed of two electrons, two particle jets and missing transverse energy. It is based on a 1 fb{sup -1} data set collected by the D0 experiment between 2002 and 2006. The reconstruction and identification of electrons and jets is of major importance in this analysis, and have been studied in events where a Z boson is produced together with one or more jets. The Z+jets process is indeed the dominant physics background to top pair production in the dielectron final state. The primary goal of this cross-section measurement is to verify Standard Model predictions. In this document, this result is also interpreted to indirectly extract the top quark mass. Moreover, the cross-section measurement is sensitive to new physics such as the existence of a charged Higgs boson. The selection established for the cross-section analysis has been used to search for a H{sup +} boson lighter than the top quark, where the latter can decay into a W{sup +} or H{sup +} boson and a b quark. The model that has been studied makes the assumption that the H{sup +} boson can only decay into a tau lepton and a neutrino.

  6. Measurement of the top quark mass in the tt¯→ lepton+jets and tt¯→ dilepton channels using √s = 7   TeV ATLAS data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.

    2015-07-17

    The top quark mass was measured in the channels tt¯→ lepton+jets and tt¯→ dilepton (lepton = e,μ) based on ATLAS data recorded in 2011. The data were taken at the LHC with a proton–proton centre-of-mass energy of √s = 7 TeV and correspond to an integrated luminosity of 4.6 fb–1. The tt¯→ lepton+jets analysis uses a three-dimensional template technique which determines the top quark mass together with a global jet energy scale factor (JSF), and a relative b-to-light-jet energy scale factor (bJSF), where the terms b-jets and light-jets refer to jets originating from b-quarks and u, d, c, s-quarks ormore »gluons, respectively. The analysis of the tt¯→ dilepton channel exploits a one-dimensional template method using the mℓb observable, defined as the average invariant mass of the two lepton+b-jet pairs in each event. The top quark mass is measured to be 172.33 ± 0.75 (stat + JSF + bJSF) ± 1.02(syst) GeV, and 173.79 ± 0.54(stat) ± 1.30(syst) GeV in the tt¯→ lepton+jets and tt¯→ dilepton channels, respectively. Thus, the combination of the two results yields mtop = 172.99 ± 0.48(stat) ± 0.78(syst) GeV, with a total uncertainty of 0.91 GeV.« less

  7. Measurement of the top quark mass in the tt¯→ lepton+jets and tt¯→ dilepton channels using √s = 7   TeV ATLAS data

    SciTech Connect (OSTI)

    Aad, G.

    2015-07-17

    The top quark mass was measured in the channels tt¯→ lepton+jets and tt¯→ dilepton (lepton = e,μ) based on ATLAS data recorded in 2011. The data were taken at the LHC with a proton–proton centre-of-mass energy of √s = 7 TeV and correspond to an integrated luminosity of 4.6 fb–1. The tt¯→ lepton+jets analysis uses a three-dimensional template technique which determines the top quark mass together with a global jet energy scale factor (JSF), and a relative b-to-light-jet energy scale factor (bJSF), where the terms b-jets and light-jets refer to jets originating from b-quarks and u, d, c, s-quarks or gluons, respectively. The analysis of the tt¯→ dilepton channel exploits a one-dimensional template method using the mℓb observable, defined as the average invariant mass of the two lepton+b-jet pairs in each event. The top quark mass is measured to be 172.33 ± 0.75 (stat + JSF + bJSF) ± 1.02(syst) GeV, and 173.79 ± 0.54(stat) ± 1.30(syst) GeV in the tt¯→ lepton+jets and tt¯→ dilepton channels, respectively. Thus, the combination of the two results yields mtop = 172.99 ± 0.48(stat) ± 0.78(syst) GeV, with a total uncertainty of 0.91 GeV.

  8. Measurement of the top quark mass in the tt¯→ lepton+jets and tt¯→ dilepton channels using √s = 7   TeV ATLAS data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.

    2015-07-17

    The top quark mass was measured in the channels tt¯→ lepton+jets and tt¯→ dilepton (lepton = e,μ) based on ATLAS data recorded in 2011. The data were taken at the LHC with a proton–proton centre-of-mass energy of √s = 7 TeV and correspond to an integrated luminosity of 4.6 fb–1. The tt¯→ lepton+jets analysis uses a three-dimensional template technique which determines the top quark mass together with a global jet energy scale factor (JSF), and a relative b-to-light-jet energy scale factor (bJSF), where the terms b-jets and light-jets refer to jets originating from b-quarks and u, d, c, s-quarks ormore » gluons, respectively. The analysis of the tt¯→ dilepton channel exploits a one-dimensional template method using the mℓb observable, defined as the average invariant mass of the two lepton+b-jet pairs in each event. The top quark mass is measured to be 172.33 ± 0.75 (stat + JSF + bJSF) ± 1.02(syst) GeV, and 173.79 ± 0.54(stat) ± 1.30(syst) GeV in the tt¯→ lepton+jets and tt¯→ dilepton channels, respectively. Thus, the combination of the two results yields mtop = 172.99 ± 0.48(stat) ± 0.78(syst) GeV, with a total uncertainty of 0.91 GeV.« less

  9. A new scheme of causal viscous hydrodynamics for relativistic heavy-ion collisions: A Riemann solver for quarkgluon plasma

    SciTech Connect (OSTI)

    Akamatsu, Yukinao; Inutsuka, Shu-ichiro; Nonaka, Chiho; Department of Physics, Nagoya University, Nagoya 464-8602 ; Takamoto, Makoto; Max-Planck-Institut fr Kernphysik, Postfach 103980, 69029 Heidelberg

    2014-01-01

    In this article, we present a state-of-the-art algorithm for solving the relativistic viscous hydrodynamics equation with the QCD equation of state. The numerical method is based on the second-order Godunov method and has less numerical dissipation, which is crucial in describing of quarkgluon plasma in high-energy heavy-ion collisions. We apply the algorithm to several numerical test problems such as sound wave propagation, shock tube and blast wave problems. In sound wave propagation, the intrinsic numerical viscosity is measured and its explicit expression is shown, which is the second-order of spatial resolution both in the presence and absence of physical viscosity. The expression of the numerical viscosity can be used to determine the maximum cell size in order to accurately measure the effect of physical viscosity in the numerical simulation.

  10. Search for neutral Higgs bosons decaying to tau pairs produced in association with b quarks in pp? collisions at ?s=1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich; Abbott, Braden Keim; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd; Alexeev, Guennadi D; Alkhazov, Georgiy D; Alton, Andrew K; Alverson, George O; Alves, Gilvan Augusto; et al

    2011-09-12

    We report results from a search for neutral Higgs bosons produced in association with b quarks using data recorded by the D0 experiment at the Fermilab Tevatron Collider and corresponding to an integrated luminosity of 7.3 fb-1. This production mode can be enhanced in several extensions of the standard model (SM) such as in its minimal supersymmetric extension (MSSM) at high tan. We search for Higgs bosons decaying to tau pairs with one tau decaying to a muon and neutrinos and the other to hadrons. The data are found to be consistent with SM expectations, and we set upper limitsmoreon the cross section times branching ratio in the Higgs boson mass range from 90 to 320 GeV/c2. We interpret our result in the MSSM parameter space, excluding tan values down to 25 for Higgs boson masses below 170 GeV/c2.less

  11. Search for a Very Light CP-Odd Higgs Boson in Top Quark Decays from pp? Collisions at ?s = 1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T; Gonzalez, B Alvarez; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Apresyan, A; et al

    2011-07-11

    We present the results of a search for a very light CP-odd Higgs boson a10 originating from top quark decays t?Hb ? W(*)a10b, and subsequently decaying into ?+?-. Using a data sample corresponding to an integrated luminosity of 2.7 fb-1 collected by the CDF II detector in pp? collisions at 1.96 TeV, we perform a search for events containing a lepton, three or more jets, and an additional isolated track with transverse momentum in the range 3 to 20 GeV/c. Observed events are consistent with background sources, and 95% C.L. limits are set on the branching ratio of t?Hb formorevarious masses of H and a10.less

  12. Measurement of the W boson helicity in top quark decays using 5.4 fb⁻¹ of pp̄ collision data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G. A.; et al

    2011-02-18

    We present a measurement of the helicity of the W boson produced in top quark decays using tt¯ decays in the l+jets and dilepton final states selected from a sample of 5.4 fb⁻¹ of collisions recorded using the D0 detector at the Fermilab Tevatron pp̄ collider. We measure the fractions of longitudinal and right-handed W bosons to be f₀=0.669±0.102[±0.078(stat.)±0.065(syst.)] and f₊=0.023±0.053[±0.041(stat.)±0.034(syst.)], respectively. This result is consistent at the 98% level with the standard model. A measurement with f₀ fixed to the value from the standard model yields f₊=0.010±0.037[±0.022(stat.)±0.030(syst.)].

  13. First Measurement of the Cross Section for Top-Quark Pair Production in Proton-Proton Collisions at $\\sqrt{s}=7$ TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan; et al.

    2011-01-01

    The first measurement of the cross section for top-quark pair production in pp collisions at the LHC at center-of-mass energy sqrt(s)= 7 TeV has been performed using 3.1 {\\pm} 0.3 inverse pb of data recorded by the CMS detector. This result utilizes the final state with two isolated, highly energetic charged leptons, large missing transverse energy, and two or more jets. Backgrounds from Drell-Yan and non-W/Z boson production are estimated from data. Eleven events are observed in the data with 2.1 {\\pm} 1.0 events expected from background. The measured cross section is 194 {\\pm} 72 (stat.) {\\pm} 24 (syst.) {\\pm} 21 (lumi.) pb, consistent with next-to-leading order predictions.

  14. Strange quark suppression and strange hadron production in pp collisions at energies available at the BNL Relativistic Heavy Ion Collider and the CERN Large Hadron Collider

    SciTech Connect (OSTI)

    Long Haiyan; Feng Shengqin; Zhou Daimei; Yan Yuliang; Ma Hailiang; Sa Benhao

    2011-09-15

    The parton and hadron cascade model PACIAE based on PYTHIA is utilized to systematically investigate strange particle production in pp collisions at energies available at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC). Globally speaking, the PACIAE results of the strange particle rapidity density at midrapidity and the transverse momentum distribution are better than those of PYTHIA (default) in comparison with STAR and ALICE experimental data. This may represent the importance of the parton and hadron rescatterings, as well as the reduction mechanism of strange quark suppression, added in the PACIAE model. The K/{pi} ratios as a function of reaction energy in pp collisions from CERN Super Proton Synchrotron (SPS) to LHC energies are also analyzed in this paper.

  15. QUARK-NOVAE IN LOW-MASS X-RAY BINARIES. II. APPLICATION TO G87-7 AND TO GRB 110328A

    SciTech Connect (OSTI)

    Ouyed, Rachid; Staff, Jan; Jaikumar, Prashanth

    2011-12-20

    We propose a simple model explaining two outstanding astrophysical problems related to compact objects: (1) that of stars such as G87-7 (alias EG 50) that constitute a class of relatively low-mass white dwarfs (WDs) which nevertheless fall away from the C/O composition and (2) that of GRB 110328A/Swift J164449.3+57345 which showed spectacularly long-lived strong X-ray flaring, posing a challenge to standard gamma-ray burst models. We argue that both these observations may have an explanation within the unified framework of a quark-nova (QN) occurring in a low-mass X-ray binary (LMXB; neutron star (NS)-WD). For LMXBs, where the binary separation is sufficiently tight, ejecta from the exploding NS triggers nuclear burning in the WD on impact, possibly leading to Fe-rich composition compact WDs with mass 0.43 M{sub Sun} < M{sub WD} < 0.72 M{sub Sun }, reminiscent of G87-7. Our results rely on the assumption, which ultimately needs to be tested by hydrodynamic and nucleosynthesis simulations, that under certain circumstances the WD can avoid the thermonuclear runaway. For heavier WDs (i.e., M{sub WD} > 0.72 M{sub Sun }) experiencing the QN shock, degeneracy will not be lifted when carbon burning begins, and a sub-Chandrasekhar Type Ia supernova may result in our model. Under slightly different conditions and for pure He WDs (i.e., M{sub WD} < 0.43 M{sub Sun }), the WD is ablated and its ashes raining down on the quark star (QS) leads to accretion-driven X-ray luminosity with energetics and duration reminiscent of GRB 110328A. We predict additional flaring activity toward the end of the accretion phase if the QS turns into a black hole.

  16. Search for the Production of Dark Matter in Association with Top-Quark Pairs in the Single-Lepton Final State in Proton-Proton Collisions at $\\sqrt{s}$ = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, V.

    2015-06-17

    A search is presented for particle dark matter produced in association with a pair of top quarks in pp collisions at a centre-of-mass energy of s√=8 TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 19.7 fb-1. This search requires the presence of one lepton, multiple jets, and large missing transverse energy. No excess of events is found above the SM expectation, and upper limits are derived on the production cross section. Interpreting the findings in the context of a scalar contact interaction between fermionic dark matter particles and top quarks, lower limits on the interaction scale are set. These limits are also interpreted in terms of the dark matter-nucleon scattering cross sections for the spin-independent scalar operator and they complement direct searches for dark matter particles in the low mass region.

  17. Search for a dark matter candidate produced in association with a single top quark in $p\\bar{p}$ collisions at $\\sqrt{s} = 1.96$ TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Anza, F.; Apollinari, G.; Appel, J.A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2012-02-01

    We report a new search for dark matter in a data sample of an integrated luminosity of 7.7 fb{sup -1} of Tevatron p{bar p} collisions at {radical}s = 1.96 TeV, collected by the CDF II detector. We search for production of a dark matter candidate, D, in association with a single top quark. We consider the hadronic decay mode of the top quark exclusively, yielding a final state of three jets with missing transverse energy. The data are consistent with the standard model; we thus set 95% confidence level upper limits on the cross section of the process p{bar p} {yields} t + D as a function of the mass of the dark-matter candidate. The limits are approximately 0.5 pb for a dark-matter particle with mass in the range of 0 - 150 GeV/c{sup 2}.

  18. Search for the Production of Dark Matter in Association with Top-Quark Pairs in the Single-Lepton Final State in Proton-Proton Collisions at $$\\sqrt{s}$$ = 8 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, V.

    2015-06-17

    A search is presented for particle dark matter produced in association with a pair of top quarks in pp collisions at a centre-of-mass energy of s√=8 TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 19.7 fb-1. This search requires the presence of one lepton, multiple jets, and large missing transverse energy. No excess of events is found above the SM expectation, and upper limits are derived on the production cross section. Interpreting the findings in the context of a scalar contact interaction between fermionic dark matter particles and topmore » quarks, lower limits on the interaction scale are set. These limits are also interpreted in terms of the dark matter-nucleon scattering cross sections for the spin-independent scalar operator and they complement direct searches for dark matter particles in the low mass region.« less

  19. Search for a Dark Matter Candidate Produced in Association with a Single Top Quark in pp̄ Collisions at √s=1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T.; Álvarez González, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Anzá, F.; Apollinari, G.; Appel, J. A.; et al

    2012-05-15

    We report a new search for dark matter in a data sample of an integrated luminosity of 7.7 fb⁻¹ of Tevatron pp¯ collisions at √s=1.96 TeV, collected by the CDF II detector. We search for production of a dark-matter candidate, D, in association with a single top quark. We consider the hadronic decay mode of the top quark exclusively, yielding a final state of three jets with missing transverse energy. The data are consistent with the standard model; we thus set 95% confidence level upper limits on the cross section of the process pp̄→t+D as a function of the massmore » of the dark-matter candidate. The limits are approximately 0.5 pb for a dark-matter particle with mass in the range of 0–150 GeV/c².« less

  20. Breaking of the number-of-constituent-quark scaling for identified-particle elliptic flow as a signal of phase change in low-energy data taken at the BNL Relativistic Heavy Ion Collider (RHIC)

    SciTech Connect (OSTI)

    Tian, J.; Jin, F.; Zhang, S.; Chen, J. H.; Ma, Y. G.; Cai, X. Z.; Ma, G. L.; Zhong, C.

    2009-06-15

    We argue that measurements of identified-particle elliptic flow in a wide energy range could shed light on the possible phase change in high-energy heavy ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC). When the hadronization process is dominated by quark coalescence, the number-of-constituent-quark (NCQ) scaling for the identified-particle elliptic flow can serve as a probe for studying the strong interacting partonic matter. In the upcoming RHIC low-energy runs, the NCQ scaling behavior may be broken because of the change of the effective degrees of freedom of the hot dense matter, which corresponds to the transition from the dominant partonic phase to the dominant hadronic phase. A multiphase transport model is used to present the dependence of NCQ scaling behavior on the different hadronization mechanisms.

  1. Search for charged Higgs bosons decaying via H+ -> tau nu in top quark pair events using pp collision data at sqrt(s) = 7 TeV with the ATLAS detector

    SciTech Connect (OSTI)

    Aad, Georges; Abbott, Brad; Abdallah, Jalal; Abdel Khalek, Samah; Abdelalim, Ahmed Ali; Abdinov, Ovsat; Abi, Babak; Abolins, Maris; AbouZeid, Ossama; Abramowicz, Halina; Abreu, Henso; /SUNY, Albany /Alberta U. /Ankara U. /Dumlupinar U. /Gazi U. /TOBB ETU, Ankara /TAEK, Ankara /Annecy, LAPP /Argonne /Arizona U. /Texas U., Arlington

    2012-04-01

    The results of a search for charged Higgs bosons are presented. The analysis is based on 4.6 fb{sup -1} of proton-proton collision data at {radical}s = 7 TeV collected by the ATLAS experiment at the Large Hadron Collider, using top quark pair events with a {tau} lepton in the final state. The data are consistent with the expected background from Standard Model processes. Assuming that the branching ratio of the charged Higgs boson to a {tau} lepton and a neutrino is 100%, this leads to upper limits on the branching ratio of top quark decays to a b quark and a charged Higgs boson between 5% and 1% for charged Higgs boson masses ranging from 90 GeV to 160 GeV, respectively. In the context of the m{sub h}{sup max} scenario of the MSSM, tan {beta} above 12-26, as well as between 1 and 2-6, can be excluded for charged Higgs boson masses between 90 GeV and 150 GeV.

  2. Search for anomalous couplings in the W tb vertex from the measurement of double differential angular decay rates of single top quarks produced in the t-channel with the ATLAS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; et al

    2016-04-05

    The electroweak production and subsequent decay of single top quarks is determined by the properties of the Wtb vertex. This vertex can be described by the complex parameters of an effective Lagrangian. An analysis of angular distributions of the decay products of single top quarks produced in the t -channel constrains these parameters simultaneously. The analysis described in this paper uses 4.6 fb-1 of proton-proton collision data at √s=7 TeV collected with the ATLAS detector at the LHC. Two parameters are measured simultaneously in this analysis. The fraction f 1 of decays containing transversely polarised W bosons is measured tomore » be 0.37 ± 0.07 (stat.⊕syst.). The phase δ - between amplitudes for transversely and longitudinally polarised W bosons recoiling against left-handed b-quarks is measured to be -0.014π ± 0.036π (stat.⊕syst.). The correlation in the measurement of these parameters is 0.15. These values result in two-dimensional limits at the 95% confidence level on the ratio of the complex coupling parameters g R and V L, yielding Re[g R /V L] ϵ [-0.36, 0.10] and Im[g R /V L] ϵ [-0.17, 0.23] with a correlation of 0.11. We find the results are in good agreement with the predictions of the Standard Model.« less

  3. A search for flavour changing neutral currents in top-quark decays in pp collision data collected with the ATLAS detector at √s = 7 TeV

    SciTech Connect (OSTI)

    Aad, Georges

    2014-09-30

    A search for flavour changing neutral current (FCNC) processes in top-quark decays by the ATLAS Collaboration is presented. Data collected from pp collisions at the LHC at a centre-of-mass energy of √s = 7 TeV during 2011, corresponding to an integrated luminosity of 2.1 fb⁻¹, were used. A search was performed for top-quark pair-production events, with one top quark decaying through the t → Zq FCNC (q = u, c) channel, and the other through the Standard Model dominant mode t → Wb. Only the decays of the Z boson to charged leptons and leptonic W-boson decays were considered as signal. Consequently, the final-state topology is characterised by the presence of three isolated charged leptons, at least two jets and missing transverse momentum from the undetected neutrino. No evidence for an FCNC signal was found. An upper limit on the t → Zq branching ratio of BR(t → Zq) < 0.73% is set at the 95% confidence level.

  4. Search for Production of Heavy Particles Decaying to Top Quarks and Invisible Particles in $p\\bar{p}$ collisions at $\\sqrt{s}=1.96$ TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2011-03-01

    We present a search for a new particle T{prime} decaying to a top-quark via T{prime} {yields} t + X, where X is an invisible particle. In a data sample with 4.8 fb{sup -1} of integrated luminosity collected by the CDF II detector at Fermilab in p{bar p} collisions with {radical}s = 1.96 TeV, we search for pair production of T0 in the lepton+jets channel, p{bar p} {yields} t{bar t} + XX {yields} {ell}{nu}bqq{prime}b + XX. We interpret our results primarily in terms of a model where T{prime} are exotic fourth generation quarks and X are dark matter particles. The data are consistent with standard model expectations, and we set 95% confidence level limits on the generic production of T{prime}{bar T}{prime} {yields} t{bar t} + XX. We apply these limits to the dark matter model and exclude the fourth generation exotic quarks T{prime} at 95% confidence level up to m{sub T{prime}} = 360 GeV/c{sup 2} for m{sub x} {<=} 100 GeV/c{sup 2}.

  5. Determination of the top-quark pole mass and strong coupling constant from the t t-bar production cross section in pp collisions at $$\\sqrt{s}$$ = 7 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chatrchyan, Serguei

    2014-08-21

    The inclusive cross section for top-quark pair production measured by the CMS experiment in proton-proton collisions at a center-of-mass energy of 7 TeV is compared to the QCD prediction at next-to-next-to-leading order with various parton distribution functions to determine the top-quark pole mass,more » $$m_t^{pole}$$, or the strong coupling constant, $$\\alpha_S$$. With the parton distribution function set NNPDF2.3, a pole mass of 176.7$$^{+3.0}_{-2.8}$$ GeV is obtained when constraining $$\\alpha_S$$ at the scale of the Z boson mass, $m_Z$, to the current world average. Alternatively, by constraining $$m_t^{pole}$$ to the latest average from direct mass measurements, a value of $$\\alpha_S(m_Z)$$ = 0.1151$$^{+0.0028}_{-0.0027}$$ is extracted. This is the first determination of $$\\alpha_S$$ using events from top-quark production.« less

  6. Observation of top quark pairs produced in association with a vector boson in pp collisions at √(s) = 8 TeV

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2015-10-06

    Measurements of the cross sections for top quark pairs produced in association with a W or Z boson are presented, using 8 TeV pp collision data corresponding to an integrated luminosity of 19.5 fb-1, collected by the CMS experiment at the LHC. We found that final states are selected in which the associated W boson decays to a charged lepton and a neutrino or the Z boson decays to two charged leptons. Signal events are identified by matching reconstructed objects in the detector to specific final state particles from tt-W or tt-Z decays. The tt-W cross section is measured to be 382+117 -102 fb with a significance of 4.8 standard deviations from the background-only hypothesis. The tt-Z cross section is measured to be 242+65 -55 fb with a significance of 6.4 standard deviations from the background-only hypothesis. These measurements are used to set bounds on five anomalous dimension-six operators that would affect the tt-W and tt-Z cross sections.

  7. Search for a Very Light CP-Odd Higgs Boson in Top Quark Decays from pp-bar; Collisions at ?s = 1.96 TeV

    SciTech Connect (OSTI)

    Aaltonen, T.

    2011-07-11

    We present the results of a search for a very light CP-odd Higgs boson a10 originating from top quark decays t?Hb ? W(*)a10b, and subsequently decaying into ?+?-. Using a data sample corresponding to an integrated luminosity of 2.7 fb-1 collected by the CDF II detector in pp-bar collisions at 1.96 TeV, we perform a search for events containing a lepton, three or more jets, and an additional isolated track with transverse momentum in the range 3 to 20 GeV/c. Observed events are consistent with background sources, and 95% C.L. limits are set on the branching ratio of t?Hb for various masses of H and a10.

  8. Measurements of single top quark production cross sections and |Vtb| in pp̄ collisions at √s=1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, Victor Mukhamedovich; Abbott, Braden Keim; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd; Alexeev, Guennadi D; Alkhazov, Georgiy D; Alton, Andrew K; Alverson, George O; Alves, Gilvan Augusto; et al

    2011-12-05

    We present measurements of production cross sections of single top quarks in pp̄ collisions at √s = 1.96 TeV in a data sample corresponding to an integrated luminosity of 5.4 fb-1 collected by the D0 detector at the Fermilab Tevatron Collider. We select events with an isolated electron or muon, an imbalance in transverse energy, and two, three, or four jets, with one or two of them containing a bottom hadron. We obtain an inclusive cross section of Σ(pp̄ → tb + X, tqb + X) = 3.43-0.74+0.73 pb and use it to extract the CKM matrix element 0.79

  9. Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at $\\sqrt{s} = 8$ $\\,\\text {TeV}$

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2014-09-17

    The measurement of a cross section for the production of top quarkantiquark pairs (tt) in association with a vector boson V (W or Z) in proton-proton collisions at ?s=8 TeV is presented. The results are based on a dataset corresponding to an integrated luminosity of 19.5 fb-1 recorded with the CMS detector at the LHC. The measurement is performed in three leptonic (e and ?) channels: a same-sign dilepton analysis targeting ttW events, and trilepton and four-lepton analyses designed for ttZ events. In the same-sign dilepton channel, the ttW cross section is measured as ?ttW=170+90-80(stat)70(syst)fb, corresponding to a significance ofmore1.6 standard deviations over the background-only hypothesis. Combining the trilepton and four-lepton channels, a direct measurement of the ttZ cross section, ?ttZ=200+80-70(stat)+40-30(syst)fb-1, is obtained with a significance of 3.1 standard deviations. Finally, the measured cross sections are compatible with standard model predictions within their experimental uncertainties. The inclusive ttV process is observed with a significance of 3.7 standard deviations from the combination of all three leptonic channels.less

  10. Heavy-quark production and elliptic flow in Au+Au collisions at √sNN=62.4 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.

    2015-04-28

    In this study, we present measurements of electrons and positrons from the semileptonic decays of heavy-flavor hadrons at midrapidity (|y|NN = 62.4 GeV. The data were collected in 2010 by the PHENIX experiment that included the new hadron-blind detector. The invariant yield of electrons from heavy-flavor decays is measured as a function of transverse momentum in the range 1 eT more »may be a result of the interplay between initial-state Cronin effects, final-state flow, and energy loss in medium. The v₂ of electrons from heavy-flavor decays is nonzero when averaged between 1.3 eT NN = 62.4 GeV. For 20%–40% centrality collisions, the v₂ at √sNN = 62.4 GeV is smaller than that for heavy-flavor decays at √sNN = 200 GeV. The v₂ of the electrons from heavy-flavor decay at the lower beam energy is also smaller than v₂ for pions. Both results indicate that the heavy-quarks interact with the medium formed in these collisions, but they may not be at the same level of thermalization with the medium as observed at √sNN = 200 GeV.« less

  11. Measuring the isotropization time of quark-gluon plasma from direct photons at energies available at the BNL Relativistic Heavy Ion Collider (RHIC)

    SciTech Connect (OSTI)

    Bhattacharya, Lusaka; Roy, Pradip

    2009-05-15

    We calculate transverse momentum distribution of direct photons from various sources by taking into account the initial state momentum anisotropy of quark-gluon plasma (QGP) and late stage transverse flow effects. To evaluate the photon yield from hadronic matter we include the contributions from baryon-meson reactions. The total photon yield, calculated for various combinations of initial conditions and transition temperatures, is then compared with the recent measurement of photon transverse momentum distribution by the PHENIX Collaboration. It is shown that because of the initial state anisotropy the photon yield from the QGP is larger by a factor of 8-10 than that of the isotropic case in the intermediate p{sub T} regime. It is also demonstrated that the presence of such an anisotropy can describe the PHENIX photon data better than the isotropic case in the present model. We show that the isotropization time thus extracted lies within the range 1.5{>=}{tau}{sub iso}{>=}0.5 fm/c for the initial conditions used here.

  12. Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at $\\sqrt{s} = 8$ $\\,\\text {TeV}$

    SciTech Connect (OSTI)

    Khachatryan, Vardan

    2014-09-17

    A measurement of the cross section for the production of top quarkantiquark pairs ( ${\\mathrm {t}}\\overline{{\\mathrm {t}}}$ ) in association with a vector boson V (W or Z) in proton-proton collisions at $\\sqrt{s} = 8$ $\\,\\text {TeV}$ is presented. The results are based on a dataset corresponding to an integrated luminosity of 19.5 fb$^{-1}$ recorded with the CMS detector at the LHC. The measurement is performed in three leptonic (e and $\\mu$) channels: a same-sign dilepton analysis targeting ${\\mathrm {t}}\\overline{{\\mathrm {t}}} \\mathrm {W} $ events, and trilepton and four-lepton analyses designed for ${\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {Z}} $ events. In the same-sign dilepton channel, the ${\\mathrm {t}}\\overline{{\\mathrm {t}}} \\mathrm {W} $ cross section is measured as $\\sigma _{{\\mathrm {t}}\\overline{{\\mathrm {t}}} \\mathrm {W}} = 170 ^{+90-80}\\,\\text {(stat)} \\pm 70\\,\\text {(syst)} \\, \\text {fb} $ , corresponding to a significance of 1.6 standard deviations over the background-only hypothesis. Combining the trilepton and four-lepton channels, a direct measurement of the ${\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {Z}} $ cross section, $\\sigma _{{\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {Z}}} = 200 ^{+80-70}\\,\\text {(stat)} ^{+40-30}\\,\\text {(syst)} \\mathrm{fb}^{-1} $ , is obtained with a significance of 3.1 standard deviations. The measured cross sections are compatible with standard model predictions within their experimental uncertainties. The inclusive ${\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {V}} $ process is observed with a significance of 3.7 standard deviations from the combination of all three leptonic channels.

  13. Constraints on models of the Higgs boson with exotic spin and parity using decays to bottom-antibottom quarks in the full CDF data set

    SciTech Connect (OSTI)

    Aaltonen, Timo Antero

    2015-04-10

    In this study, a search for particles with the same mass and couplings as those of the standard model Higgs boson but different spin and parity quantum numbers is presented. We test two specific alternative Higgs boson hypotheses: a pseudoscalar Higgs boson with spin-parity JP = 0 and a gravitonlike Higgs boson with JP = 2+, assuming for both a mass of 125 GeV/c2. We search for these exotic states produced in association with a vector boson and decaying into a bottom-antibottom quark pair. The vector boson is reconstructed through its decay into an electron or muon pair, or an electron or muon and a neutrino, or it is inferred from an imbalance in total transverse momentum. We use expected kinematic differences between events containing exotic Higgs bosons and those containing standard model Higgs bosons. The data were collected by the CDF experiment at the Tevatron proton-antiproton collider, operating at a center-of-mass energy of √s = 1.96 TeV, and correspond to an integrated luminosity of 9.45 fb–1. We exclude deviations from the predictions of the standard model with a Higgs boson of mass 125 GeV/c2 at the level of 5 standard deviations, assuming signal strengths for exotic boson production equal to the prediction for the standard model Higgs boson, and set upper limits of approximately 30% relative to the standard model rate on the possible rate of production of each exotic state.

  14. Heavy-quark production and elliptic flow in Au+Au collisions at ?sNN=62.4 GeV

    SciTech Connect (OSTI)

    Adare, A.

    2015-04-28

    In this study, we present measurements of electrons and positrons from the semileptonic decays of heavy-flavor hadrons at midrapidity (|y|< 0.35) in Au+Au collisions at ?sNN = 62.4 GeV. The data were collected in 2010 by the PHENIX experiment that included the new hadron-blind detector. The invariant yield of electrons from heavy-flavor decays is measured as a function of transverse momentum in the range 1 < peT < 5 GeV/c. The invariant yield per binary collision is slightly enhanced above the p+p reference in Au+Au 0%20%, 20%40%, and 40%60% centralities at a comparable level. At this low beam energy this may be a result of the interplay between initial-state Cronin effects, final-state flow, and energy loss in medium. The v? of electrons from heavy-flavor decays is nonzero when averaged between 1.3 < peT < 2.5 GeV/c for 0%40% centrality collisions at ?sNN = 62.4 GeV. For 20%40% centrality collisions, the v? at ?sNN = 62.4 GeV is smaller than that for heavy-flavor decays at ?sNN = 200 GeV. The v? of the electrons from heavy-flavor decay at the lower beam energy is also smaller than v? for pions. Both results indicate that the heavy-quarks interact with the medium formed in these collisions, but they may not be at the same level of thermalization with the medium as observed at ?sNN = 200 GeV.

  15. Heavy-quark production and elliptic flow in Au+Au collisions at √sNN=62.4 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.

    2015-04-28

    In this study, we present measurements of electrons and positrons from the semileptonic decays of heavy-flavor hadrons at midrapidity (|y|< 0.35) in Au+Au collisions at √sNN = 62.4 GeV. The data were collected in 2010 by the PHENIX experiment that included the new hadron-blind detector. The invariant yield of electrons from heavy-flavor decays is measured as a function of transverse momentum in the range 1 < peT < 5 GeV/c. The invariant yield per binary collision is slightly enhanced above the p+p reference in Au+Au 0%–20%, 20%–40%, and 40%–60% centralities at a comparable level. At this low beam energy thismore » may be a result of the interplay between initial-state Cronin effects, final-state flow, and energy loss in medium. The v₂ of electrons from heavy-flavor decays is nonzero when averaged between 1.3 < peT < 2.5 GeV/c for 0%–40% centrality collisions at √sNN = 62.4 GeV. For 20%–40% centrality collisions, the v₂ at √sNN = 62.4 GeV is smaller than that for heavy-flavor decays at √sNN = 200 GeV. The v₂ of the electrons from heavy-flavor decay at the lower beam energy is also smaller than v₂ for pions. Both results indicate that the heavy-quarks interact with the medium formed in these collisions, but they may not be at the same level of thermalization with the medium as observed at √sNN = 200 GeV.« less

  16. Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at $\\sqrt{s} = 8$ $\\,\\text {TeV}$

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2014-09-17

    A measurement of the cross section for the production of top quarkantiquark pairs ( ${\\mathrm {t}}\\overline{{\\mathrm {t}}}$ ) in association with a vector boson V (W or Z) in proton-proton collisions at $\\sqrt{s} = 8$ $\\,\\text {TeV}$ is presented. The results are based on a dataset corresponding to an integrated luminosity of 19.5 fb$^{-1}$ recorded with the CMS detector at the LHC. The measurement is performed in three leptonic (e and $\\mu$) channels: a same-sign dilepton analysis targeting ${\\mathrm {t}}\\overline{{\\mathrm {t}}} \\mathrm {W} $ events, and trilepton and four-lepton analyses designed for ${\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {Z}} $ events. Inmorethe same-sign dilepton channel, the ${\\mathrm {t}}\\overline{{\\mathrm {t}}} \\mathrm {W} $ cross section is measured as $\\sigma _{{\\mathrm {t}}\\overline{{\\mathrm {t}}} \\mathrm {W}} = 170 ^{+90-80}\\,\\text {(stat)} \\pm 70\\,\\text {(syst)} \\, \\text {fb} $ , corresponding to a significance of 1.6 standard deviations over the background-only hypothesis. Combining the trilepton and four-lepton channels, a direct measurement of the ${\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {Z}} $ cross section, $\\sigma _{{\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {Z}}} = 200 ^{+80-70}\\,\\text {(stat)} ^{+40-30}\\,\\text {(syst)} \\mathrm{fb}^{-1} $ , is obtained with a significance of 3.1 standard deviations. The measured cross sections are compatible with standard model predictions within their experimental uncertainties. The inclusive ${\\mathrm {t}}\\overline{{\\mathrm {t}}} {\\mathrm {V}} $ process is observed with a significance of 3.7 standard deviations from the combination of all three leptonic channels.less

  17. Λb → pℓ¯ν¯ℓ and Λb → Λcℓ¯ν¯ℓ form factors from lattice QCD with relativistic heavy quarks

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Detmold, William; Lehner, Christoph; Meinel, Stefan

    2015-08-04

    Measurements of the Λb → pℓ¯ν¯ℓ and Λb → Λcℓ¯ν¯ℓ decay rates can be used to determine the magnitudes of the Cabibbo-Kobayashi-Maskawa matrix elements Vub and Vcb, provided that the relevant hadronic form factors are known. Here we present a precise calculation of these form factors using lattice QCD with 2+1 flavors of dynamical domain-wall fermions. The b and c quarks are implemented with relativistic heavy-quark actions, allowing us to work directly at the physical heavy-quark masses. The lattice computation is performed for six different pion masses and two different lattice spacings, using gauge-field configurations generated by the RBC andmore » UKQCD Collaborations. The b → u and b → c currents are renormalized with a mostly nonperturbative method. We extrapolate the form factor results to the physical pion mass and the continuum limit, parametrizing the q² dependence using z expansions. The form factors are presented in such a way as to enable the correlated propagation of both statistical and systematic uncertainties into derived quantities such as differential decay rates and asymmetries. Using these form factors, we present predictions for the Λb → pℓ¯ν¯ℓ and Λb → Λcℓ¯ν¯ℓdifferential and integrated decay rates. Combined with experimental data, our results enable determinations of |Vub|, |Vcb|, and |Vub/Vcb| with theory uncertainties of 4.4%, 2.2%, and 4.9%, respectively.« less

  18. Current trends in non-accelerator particle physics: 1, Neutrino mass and oscillation. 2, High energy neutrino astrophysics. 3, Detection of dark matter. 4, Search for strange quark matter. 5, Magnetic monopole searches

    SciTech Connect (OSTI)

    He, Yudong |

    1995-07-01

    This report is a compilation of papers reflecting current trends in non-accelerator particle physics, corresponding to talks that its author was invited to present at the Workshop on Tibet Cosmic Ray Experiment and Related Physics Topics held in Beijing, China, April 4--13, 1995. The papers are entitled `Neutrino Mass and Oscillation`, `High Energy Neutrino Astrophysics`, `Detection of Dark Matter`, `Search for Strange Quark Matter`, and `Magnetic Monopole Searches`. The report is introduced by a survey of the field and a brief description of each of the author`s papers.

  19. Measurement of sin2 ??eff and Z-light quark couplings using the forward-backward charge asymmetry in pp? -> Z/gamma* -> e+e- events with L=5.0 fb-1 at ?s=1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abazov, V. M.

    2011-07-26

    We measure the mass dependence of the forward-backward charge asymmetry in 157,553 pp? = Z/?* = e+e- interactions, corresponding to 5.0 fb-1 of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider at ?s = 1.96 TeV. The effective weak mixing angle (??eff) from this process involving predominantly the first generation of quarks is extracted as sin2 ??eff = 0.2309 0.0008 (stat.) 0.0006 (syst.). We also present the most precise direct measurement of the vector and axial-vector couplings of u and d quarks to the Z boson.

  20. Search for flavour-changing neutral current top-quark decays to qZ in pp collision data collected with the ATLAS detector at √s = 8 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; et al

    2016-01-08

    A search for the flavour-changing neutral-current decay t → qZ is presented. Data collected by the ATLAS detector during 2012 from proton–proton collisions at the Large Hadron Collider at a centre-of-mass energy of √s = 8 TeV, corresponding to an integrated luminosity of 20.3 fb–1 , are analysed. Top-quark pair-production events with one top quark decaying through the t → qZ ( q=u,c ) channel and the other through the dominant Standard Model mode t → bW are considered as signal. Only the decays of the Z boson to charged leptons and leptonic W boson decays are used. Furthermore, nomore » evidence for a signal is found and an observed (expected) upper limit on the t → qZ branching ratio of 7×10–4 ( 8×10–4) is set at the 95 % confidence level« less