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1

Top Quark Mass Measurements at the Tevatron  

SciTech Connect

We report the latest results on the top-quark mass and on the top-antitop mass difference from the CDF and D0 collaborations using data collected at the Fermilab Tevatron p{bar p} collider at {radical}s = 1.96 TeV. We discuss general issues in top-quark mass measurements and present new results from direct measurements and from top-pair production cross-section. We also report new results on the top-antitop mass difference.

Ye, Zhenyu; /Fermilab

2011-07-01T23:59:59.000Z

2

World average top-quark mass  

SciTech Connect

This paper summarizes a talk given at the Top2008 Workshop at La Biodola, Isola d Elba, Italy. The status of the world average top-quark mass is discussed. Some comments about the challanges facing the experiments in order to further improve the precision are offered.

Glenzinski, D.; /Fermilab

2008-01-01T23:59:59.000Z

3

Top quark mass measurement at the Tevatron  

SciTech Connect

The authors report on the latest experimental measurements of the top quark mass by the CDF and D0 Collaborations at the Fermilab Tevatron. They present a new top mass measurement using the t{bar t} events collected by the D0 Collaboration in Run I between 1994 and 1996. This result is combined with previous measurements to yield a new world top mass average. They also describe several preliminary results using up to 193 pb{sup -1} of t{bar t} events produced in {bar p}p collisions at {radical}s = 1.96 TeV during the Run II of the Tevatron.

Guimaraes da Costa, Joao; /Harvard U.

2004-12-01T23:59:59.000Z

4

edited1_TopQuarkMass  

NLE Websites -- All DOE Office Websites (Extended Search)

CALCULATE THE TOP QUARK MASS CALCULATE THE TOP QUARK MASS TEACHER NOTES DESCRIPTION Students use momentum conservation, energy conservation and two-dimensional vector addition to calculate the mass of the heaviest of the six known quarks. They gather data from data plots from the DØ experiment at Fermilab. The events were chosen carefully; all of the decay products moved in a plane perpendicular to the beam. This makes the vector addition much simpler. STANDARDS National Science Education Standards (U.S. National Research Council) * Physical Science Content Standard B: As a result of this activity . . . students should develop an understanding of: o Conservation of energy and increase in disorder. o Interactions in energy and matter. LEARNING OBJECTIVES Students will know and be able to:

5

Top quark mass and property measurements at Tevatron  

Science Conference Proceedings (OSTI)

The top quark, discovered in 1995 at the Fermilab Tevatron collider from CDF and D0 experiments, remains by far the most interesting particle to test standard model because of its large mass and unique properties. Having data collected about 10 fb{sup -1} of integrated luminosity of p{bar p} collision, both experiments have been studied the top quark in all the possible directions. In this article, we present the recent measurements of the top quark properties from Tevatron including the mass, width, spin correlation, and W boson helicity using t{bar t} signature.

Lee, Hyun Su

2012-01-01T23:59:59.000Z

6

Top Quark  

NLE Websites -- All DOE Office Websites (Extended Search)

quark TOP Volver Principal ESTOY PERDIDO El 2 de marzo de 1995, el Fermilab anunci el descubrimiento del quark top, el ltimo de los seis quarks, cuya existencia haba sido...

7

Measurements of the top quark mass at the Tevatron  

Science Conference Proceedings (OSTI)

The mass of the top quark (m{sub top}) is a fundamental parameter of the standard model (SM). Currently, its most precise measurements are performed by the CDF and D0 collaborations at the Fermilab Tevatron p{bar p} collider at a centre-of-mass energy of {radical}s = 1.96 TeV. We review the most recent of those measurements, performed on data samples of up to 8.7 fb{sup -1} of integrated luminosity. The Tevatron combination using up to 5.8 fb{sup -1} of data results in a preliminary world average top quark mass of m{sub top} = 173.2 {+-} 0.9 GeV. This corresponds to a relative precision of about 0.54%. We conclude with an outlook of anticipated precision the final measurement of m{sub top} at the Tevatron.

Brandt, Oleg; /Gottingen U., II. Phys. Inst.

2012-04-01T23:59:59.000Z

8

A top quark mass measurement using a matrix element method  

Science Conference Proceedings (OSTI)

A measurement of the mass of the top quark is presented, using top-antitop pair (t{bar t}) candidate events for the lepton+jets decay channel. The measurement makes use of Tevatron p{bar p} collision data at centre-of-mass energy {radical}s = 1.96 TeV, collected at the CDF detector. The top quark mass is measured by employing an unbinned maximum likelihood method where the event probability density functions are calculated using signal (t{bar t}) and background (W+jets) matrix elements, as well as a set of parameterised jet-to-parton mapping functions. The likelihood function is maximised with respect to the top quark mass, the fraction of signal events, and a correction to the jet energy scale (JES) of the calorimeter jets. The simultaneous measurement of the JES correction ({Delta}{sub JES}) provides an in situ jet energy calibration based on the known mass of the hadronically decaying W boson. Using 578 lepton+jets candidate events corresponding to 3.2 fb{sup -1} of integrated luminosity, the top quark mass is measured to be m{sub t} = 172.4 {+-} 1.4 (stat+{Delta}{sub JES}) {+-} 1.3 (syst) GeV=c{sup 2}, one of the most precise single measurements to date.

Linacre, Jacob Thomas; /Oxford U.

2010-02-01T23:59:59.000Z

9

Precision Top-Quark Mass Measurements at CDF  

Science Conference Proceedings (OSTI)

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}.

Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U. /Fermilab; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Arisawa, T.; /Waseda U.; Artikov, A.; /Dubna, JINR /Texas A-M

2012-07-01T23:59:59.000Z

10

Top Quark Activitiy Introduction  

NLE Websites -- All DOE Office Websites (Extended Search)

of Momentum to Calculate the Mass of the Top Quark from D-Zero Data Making top quark data accessible to students. Ed Home - Data Home - Teacher Page - Student Activity Page -...

11

Measurements of the top quark mass and decay width with the D0 detector  

SciTech Connect

The top quark discovery in 1995 at Fermilab is one of the major proofs of the standard model (SM). Due to its unique place in SM, the top quark is an important particle for testing the theory and probing for new physics. This article presents most recent measurements of top quark properties from the D0 detector. In particular, the measurement of the top quark mass, the top antitop mass difference and the top quark decay width. The discovery of the top quark in 1995 confirmed the existence of a third generation of quarks predicted in the standard model (SM). Being the heaviest elementary particle known, the top quark appears to become an important particle in our understanding of the standard model and physics beyond it. Because of its large mass the top quark has a very short lifetime, much shorter than the hadronization time. The predicted lifetime is only 3.3 {center_dot} 10{sup -25}s. Top quark is the only quark whose properties can be studied in isolation. A Lorentz-invariant local Quantum Field Theory, the standard model is expected to conserve CP. Due to its unique properties, the top quark provides a perfect test of CPT invariance in the standard model. An ability to look at the quark before being hadronized allows to measure directly mass of the top quark and its antiquark. An observation of a mass difference between particle and antiparticle would indicate violation of CPT invariance. Top quark through its radiative loop correction to the W mass constrains the mass of the Higgs boson. A precise measurement of the top quark mass provides useful information to the search of Higgs boson by constraining its region of possible masses. Another interesting aspect is that the top quark's Yukawa coupling to the Higgs boson is very close to unity (0.996 {+-} 0.006). That implies it may play a special role in the electroweak symmetry breaking mechanism.

Ilchenko, Yuriy

2011-11-01T23:59:59.000Z

12

Top quark physics  

Science Conference Proceedings (OSTI)

The top quark, when it was finally discovered at Fermilab in 1995 completed the three-generation structure of the Standard Model (SM) and opened up the new field of top quark physics. Viewed as just another SM quark, the top quark appears to be a rather uninteresting species. Produced predominantly, in hadron-hadron collisions, through strong interactions, it decays rapidly without forming hadrons, and almost exclusively through the single mode t {r_arrow} Wb. The relevant CKM coupling V{sub tb} is already determined by the (three-generation) unitarity of the CKM matrix. Rare decays and CP violation are unmeasurable small in the SM. Yet the top quark is distinguished by its large mass, about 35 times larger than the mass of the next heavy quark, and intriguingly close to the scale of electroweak (EW) symmetry breaking. This unique property raises a number of interesting questions. Is the top quark mass generated by the Higgs mechanism as the SM predicts and is its mass related to the top-Higgs-Yukawa coupling? Or does it play an even more fundamental role in the EW symmetry breaking mechanism? If there are new particles lighter than the top quark, does the top quark decay into them? Could non-SM physics first manifest itself in non-standard couplings of the top quark which show up as anomalies in top quark production and decays? Top quark physics tries to answer these questions. Several properties of the top quark have already been examined at the Tevatron. These include studies of the kinematical properties of top production, the measurements of the top mass, of the top production cross-section, the reconstruction of t{bar t}pairs in the fully hadronic final states, the study of {tau} decays of the top quark, the reconstruction of hadronic decays of the W boson from top decays, the search for flavor changing neutral current decays, the measurement of the W helicity in top decays, and bounds on t{bar t} spin correlations. Most of these measurements are limited by the small sample of top quarks collected at the Tevatron up to now. The LHC is, in comparison, a top factory, producing about 8 million t{bar t}pairs per experiment per year at low luminosity (10 fb{sup {minus}1}/year), and another few million (anti-)tops in EW single (anti-)top quark production. They therefore expect that top quark properties can be examined with significant precision at the LHC. Entirely new measurements can be contemplated on the basis of the large available statistics.

Ahmadov, A.; Azuelos, G.; Bauer, U.; Belyaev, A.; Berger, E. L.; Sullivan, Z.; Tait, T. M. P.

2000-03-24T23:59:59.000Z

13

Precision measurements of the top quark mass and width with the D0 detector  

Science Conference Proceedings (OSTI)

Since the discovery of the top quark in 1995 at the Fermliab Tevatron Collider, top quark properties have been measured with ever higher precision. In this article, recent measurements of the top quark mass and its width using up to 3.6 fb{sup -1} of D0 data are summarized. Different techniques and final states have been examined and no deviations within these measurements have been observed. In addition to the direct measurements, a measurement of the top quark mass from its production cross section and a measurement of the top-antitop quark mass difference are discussed. With a mass of 173.3 {+-} 1.1 GeV, the top quark is the heaviest of all known fundamental particles. Due to the high mass, its Yukawa coupling is close to unity suggesting that it may play a special role in electroweak symmetry breaking. Precise measurements of both, the W boson and the top quark mass, constrain the mass of the yet unobserved Higgs boson and allow to restrict certain extensions of the Standard Model. At the Tevatron collider with a center-of-mass energy of 1.96 TeV, 85% of the top quark pairs are produced in quark-antiquark annihilation; 15% originate from gluon fusion. Top quarks are predicted to decay almost exclusively to a W boson and a bottom quark. According to the number of hadronic W decays, top events are classified into all-jets, lepton+jets and dilepton events. The lepton+jets channel is characterized by four jets, one isolated, energetic charged lepton and missing transverse energy. With 30%, the branching fraction of the lepton+jets channel is about seven times larger than the one of the dilepton channel whereas the signal to background ratio is about three times smaller. The main background in this final state comes from W +jets events. Instrumental background arises from events in which a jet is misidentified as an electron and events with heavy hadrons that decay into leptons which pass the isolation requirements. The topology of the dilepton channel is described by two jets, two isolated, energetic charged leptons and significant missing transverse energy from the undetected neutrinos. The main background are Z + jets and diboson events (WW/WZ/ZZ+jets) as well as instrumental background as characterized above. At the D0 experiment, different techniques are used to measure the top quark mass. They are summarized in the following sections together with the first measurement of the top anti-top quark mass difference and the first precise determination of the top quark width.

Grohsjean, Alexander; /IRFU, SPP, Saclay

2010-01-01T23:59:59.000Z

14

Top quark physics: Overview  

SciTech Connect

In this presentation I will primarily focus on top quark physics but I will include a discussion of the W-boson mass and the possibility of discovering a light Higgs boson via associated production at the Tevatron.

Parke, S.

1998-01-01T23:59:59.000Z

15

Top Quark Properties  

Science Conference Proceedings (OSTI)

Since its discovery in 1995 by the CDF and D0 collaborations at the Fermilab Tevatron collider, the top quark has undergone intensive studies. Besides the Tevatron experiments, with the start of the LHC in 2010 a top quark factory started its operation. It is now possible to measure top quark properties simultaneously at four different experiments, namely ATLAS and CMS at LHC and CDF and D0 at Tevatron. Having collected thousands of top quarks each, several top quark properties have been measured precisely, while others are being measured for the first time. In this article, recent measurements of top quark properties from ATLAS, CDF, CMS and D0 are presented, using up to 5.4 fb{sup -1} of integrated luminosity at the Tevatron and 1.1 fb{sup -1} at the LHC. In particular, measurements of the top quark mass, mass difference, foward backward charge asymmetry, t{bar t} spin correlations, the ratio of branching fractions, W helicity, anomalous couplings, color flow and the search for flavor changing neutral currents are discussed.

Peters, Yvonne

2011-12-01T23:59:59.000Z

16

The Top Quark's Discovery  

NLE Websites -- All DOE Office Websites (Extended Search)

Im Mrz 1995, teilte Fermilab die Entdeckung des top Quark - des letzten der sechs vorhergesagten Quarks - mit. Die Suche begann im Jahre 1977, zusammen mit der erfolgreichen...

17

The Top Quark's Discovery  

NLE Websites -- All DOE Office Websites (Extended Search)

1995, Fermilab announced the discovery of the top quark, the last of the six predicted quarks. The search began in 1977 when physicists found the fifth quark, bottom, at Fermilab....

18

Top Quark Activitiy Introduction  

NLE Websites -- All DOE Office Websites (Extended Search)

Usa la conservacin del momento lineal para calcular la masa del quark top a partir de datos de D Los datos del quark top al alcance de los estudiantes. Para profesores -...

19

Top Quark Production at the Tevatron Collider  

Science Conference Proceedings (OSTI)

Top quark physics has been a rich testing ground for the standard model since the top quark discovery in 1995. The large mass of top quark suggests that it could play a special role in searches for new phenomena. In this paper I provide an overview of recent top quark production cross section measurements from both CDF and D0 collaborations and also some new physics searches done in the top quark sector.

Li, Liang; /UC, Riverside

2011-07-01T23:59:59.000Z

20

A measurement of the top quark mass with a matrix element method  

SciTech Connect

The authors present a measurement of the mass of the top quark. The event sample is selected from proton-antiproton collisions, at 1.96 TeV center-of-mass energy, observed with the CDF detector at Fermilab's Tevatron. They consider a 318 pb{sup -1} dataset collected between March 2002 and August 2004. They select events that contain one energetic lepton, large missing transverse energy, exactly four energetic jets, and at least one displaced vertex b tag. The analysis uses leading-order t{bar t} and background matrix elements along with parameterized parton showering to construct event-by-event likelihoods as a function of top quark mass. From the 63 events observed with the 318 pb{sup -1} dataset they extract a top quark mass of 172.0 {+-} 2.6(stat) {+-} 3.3(syst) GeV/c{sup 2} from the joint likelihood. The mean expected statistical uncertainty is 3.2 GeV/c{sup 2} for m{sub t} = 178 GTeV/c{sup 2} and 3.1 GeV/c{sup 2} for m{sub t} = 172.5 GeV/c{sup 2}. The systematic error is dominated by the uncertainty of the jet energy scale.

Gibson, Adam Paul; /UC, Berkeley

2006-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "top quark mass" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Top quark production at the Tevatron  

Science Conference Proceedings (OSTI)

The Fermilab Tevatron has, until recently, been the only accelerator with sufficient energy to produce top quarks. The CDF and D0 experiments have collected large samples of top quarks. We report on recent top quark production measurements of the single top and t{bar t} production cross sections, as well as studies of the t{bar t} invariant mass distribution and a search for highly boosted top quarks.

Varnes, Erich W.; /Arizona U.

2010-09-01T23:59:59.000Z

22

Measurement of the Top Quark Mass at CDF Using the Template Method in the Lepton + Jets Channel  

SciTech Connect

A measurement of the top quark mass in p{bar p} collisions at {radical}s = 1.96 TeV is presented. The analysis uses a template method, in which the overconstrained kinematics of the Lepton+Jets channel of the t{bar t} system are used to measure a single quantity, the reconstructed top quark mass, that is strongly correlated with the true top quark mass. in addition, the dijet mass of the hadronically decaying W boson is used to constrain in situ the uncertain jet energy scale in the CDF detector. Two-dimensional probability density functions are derived using a kernel density estimate-based machinery. Using 1.9 fb{sup -1} of data, the top quark mass is measured to be 171.8{sub -1.9}{sup +1.9}(stat.) {+-} 1.0(syst.)GeV/c{sup 2}.

Adelman, Jahred A.; /Chicago U.

2008-05-01T23:59:59.000Z

23

Direct measurement of the mass difference between top and antitop quarks  

SciTech Connect

We present a direct measurement of the mass difference between top and antitop quarks ({Delta}m) in lepton+jets t{bar t} final states using the 'matrix element' method. The purity of the lepton+jets sample is enhanced for t{bar t} events by identifying at least one of the jet as originating from a b quark. The analyzed data correspond to 3.6 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV acquired by D0 in Run II of the Fermilab Tevatron Collider. The combination of the e+jets and m+jets channels yields {Delta}m = 0.8 {+-} 1.8 (stat) {+-} 0.5 (syst) GeV, which is in agreement with the standard model expectation of no mass difference.

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.

2011-06-01T23:59:59.000Z

24

Top-quark mass measurement in events with jets and missing transverse energy using the full CDF data set  

E-Print Network (OSTI)

We present a measurement of the top-quark mass using the full data set of Tevatron $\\sqrt{s} = 1.96$ TeV proton-antiproton collisions recorded by the CDF II detector, corresponding to an integrated luminosity of \\invfb{8.7}. The analysis uses events with one semileptonic $t$ or $\\bar{t}$ decay, but without detection of the electron or muon. We select events with significant missing transverse energy and multiple jets. We veto events containing identified electrons or muons. We obtain distributions of the top-quark masses and the invariant mass of the two jets from $W$-boson decays from data and compare these to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with {\\it in situ} calibration. A likelihood fit of the templates from signal and background events to the data yields the top-quark mass, $\\mtop = \\gevcc{\\measStatSyst{173.93}{1.64}{0.87}}$. This result is the most precise measurement to date of the mass of the top quark in this event topology.

CDF Collaboration

2013-05-15T23:59:59.000Z

25

Triggering Top Quark Events  

E-Print Network (OSTI)

Collisions at the LHC occur at a rate of up to 40 MHz, much larger than the 200 Hz storage capacity of the ATLAS experiment. The ATLAS trigger system has the challenging task of rejecting 99.9995 % of the events produced in collisions, while keeping those needed to achieve the physics goals of the experiment. This note evaluates the expected performance of the trigger system in top quark events by investigating the response of the trigger system to single objects such as a muon, an electron or a jet originating from top quark decays. In addition, the methodology needed to efficiently select top quark events in the online trigger system is discussed including methods to determine trigger efficiencies from data.

The ATLAS collaboration

2009-01-01T23:59:59.000Z

26

Observation of the Top Quark  

E-Print Network (OSTI)

The D collaboration reports on a search for the Standard Model top quark in pp collisions at p s = 1:8 TeV at the Fermilab Tevatron, with an integrated luminosity of approximately 50 pb \\Gamma1 . We have searched for t t production in the dilepton and single-lepton decay channels, with and without tagging of b-quark jets. We observed 17 events with an expected background of 3:8 \\Sigma 0:6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2 \\Theta 10 \\Gamma6 (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measure its mass to be 199 +19 \\Gamma21 (stat.) \\Sigma22 (syst.) GeV/c 2 and its production cross section to be 6:4 \\Sigma 2:2 pb. Typeset using REVT E X 3 In the Standard Model (SM), the top quark is the weak isospin partner of the b quark. The D collaboration published a lower limit on the mas...

Abachi Abbott Abolins

1995-01-01T23:59:59.000Z

27

Observation of the Top Quark  

E-Print Network (OSTI)

The DØ collaboration reports on a search for the Standard Model top quark in p¯p collisions at p s = 1:8 TeV at the Fermilab Tevatron, with an integrated luminosity of approximately 50 pb \\Gamma1 . We have searched for t ¯ t production in the dilepton and single-lepton decay channels, with and without tagging of b-quark jets. We observed 17 events with an expected background of 3:8 \\Sigma 0:6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2 \\Theta 10 \\Gamma6 (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measure its mass to be 199 +19 \\Gamma21 (stat.) \\Sigma22 (syst.) GeV/c 2 and its production cross section to be 6:4 \\Sigma 2:2 pb. Typeset using REVT E X In the Standard Model (SM), the top quark is the weak isospin partner of the b quark. The DØ collaboration published a lower limit on the m...

Abachi Abbott

1995-01-01T23:59:59.000Z

28

Precise measurement of the top quark mass in the dilepton channel at D0  

E-Print Network (OSTI)

We measure the top quark mass (mt) in ppbar collisions at a center of mass energy of 1.96 TeV using dilepton ttbar->W+bW-bbar->l+nubl-nubarbbar events, where l denotes an electron, a muon, or a tau that decays leptonically. The data correspond to an integrated luminosity of 5.4 fb-1 collected with the D0 detector at the Fermilab Tevatron Collider. We obtain mt = 174.0 +- 1.8(stat) +- 2.4(syst) GeV, which is in agreement with the current world average mt = 173.3 +- 1.1 GeV. This is currently the most precise measurement of mt in the dilepton channel.

D0 Collaboration; V. M. Abazov; B. Abbott; B. S. Acharya; M. Adams; T. Adams; G. D. Alexeev; G. Alkhazov; A. Alton; G. Alverson; G. A. Alves; L. S. Ancu; M. Aoki; M. Arov; A. Askew; B. Åsman; O. Atramentov; C. Avila; J. BackusMayes; F. Badaud; L. Bagby; B. Baldin; D. V. Bandurin; S. Banerjee; E. Barberis; P. Baringer; J. Barreto; J. F. Bartlett; U. Bassler; V. Bazterra; S. Beale; A. Bean; M. Begalli; M. Begel; C. Belanger-Champagne; L. Bellantoni; S. B. Beri; G. Bernardi; R. Bernhard; I. Bertram; M. Besançon; R. Beuselinck; V. A. Bezzubov; P. C. Bhat; V. Bhatnagar; G. Blazey; S. Blessing; K. Bloom; A. Boehnlein; D. Boline; E. E. Boos; G. Borissov; T. Bose; A. Brandt; O. Brandt; R. Brock; G. Brooijmans; A. Bross; D. Brown; J. Brown; X. B. Bu; M. Buehler; V. Buescher; V. Bunichev; S. Burdin; T. H. Burnett; C. P. Buszello; B. Calpas; E. Camacho-Pérez; M. A. Carrasco-Lizarraga; B. C. K. Casey; H. Castilla-Valdez; S. Chakrabarti; D. Chakraborty; K. M. Chan; A. Chandra; G. Chen; S. Chevalier-Théry; D. K. Cho; S. W. Cho; S. Choi; B. Choudhary; S. Cihangir; D. Claes; J. Clutter; M. Cooke; W. E. Cooper; M. Corcoran; F. Couderc; M. -C. Cousinou; A. Croc; D. Cutts; A. Das; G. Davies; K. De; S. J. de Jong; E. De La Cruz-Burelo; F. Déliot; M. Demarteau; R. Demina; D. Denisov; S. P. Denisov; S. Desai; C. Deterre; K. DeVaughan; H. T. Diehl; M. Diesburg; A. Dominguez; T. Dorland; A. Dubey; L. V. Dudko; D. Duggan; A. Duperrin; S. Dutt; A. Dyshkant; M. Eads; D. Edmunds; J. Ellison; V. D. Elvira; Y. Enari; H. Evans; A. Evdokimov; V. N. Evdokimov; G. Facini; T. Ferbel; F. Fiedler; F. Filthaut; W. Fisher; H. E. Fisk; M. Fortner; H. Fox; S. Fuess; A. Garcia-Bellido; V. Gavrilov; P. Gay; W. Geng; D. Gerbaudo; C. E. Gerber; Y. Gershtein; G. Ginther; G. Golovanov; A. Goussiou; P. D. Grannis; S. Greder; H. Greenlee; Z. D. Greenwood; E. M. Gregores; G. Grenier; Ph. Gris; J. -F. Grivaz; A. Grohsjean; S. Grünendahl; M. W. Grünewald; T. Guillemin; F. Guo; G. Gutierrez; P. Gutierrez; A. Haas; S. Hagopian; J. Haley; L. Han; K. Harder; A. Harel; J. M. Hauptman; J. Hays; T. Head; T. Hebbeker; D. Hedin; H. Hegab; A. P. Heinson; U. Heintz; C. Hensel; I. Heredia-De La Cruz; K. Herner; G. Hesketh; M. D. Hildreth; R. Hirosky; T. Hoang; J. D. Hobbs; B. Hoeneisen; M. Hohlfeld; Z. Hubacek; N. Huske; V. Hynek; I. Iashvili; R. Illingworth; A. S. Ito; S. Jabeen; M. Jaffré; D. Jamin; A. Jayasinghe; R. Jesik; K. Johns; M. Johnson; D. Johnston; A. Jonckheere; P. Jonsson; J. Joshi; A. W. Jung; A. Juste; K. Kaadze; E. Kajfasz; D. Karmanov; P. A. Kasper; I. Katsanos; R. Kehoe; S. Kermiche; N. Khalatyan; A. Khanov; A. Kharchilava; Y. N. Kharzheev; D. Khatidze; M. H. Kirby; J. M. Kohli; A. V. Kozelov; J. Kraus; S. Kulikov; A. Kumar; A. Kupco; T. Kur?a; V. A. Kuzmin; J. Kvita; S. Lammers; G. Landsberg; P. Lebrun; H. S. Lee; S. W. Lee; W. M. Lee; J. Lellouch; L. Li; Q. Z. Li; S. M. Lietti; J. K. Lim; D. Lincoln; J. Linnemann; V. V. Lipaev; R. Lipton; Y. Liu; Z. Liu; A. Lobodenko; M. Lokajicek; R. Lopes de Sa; H. J. Lubatti; R. Luna-Garcia; A. L. Lyon; A. K. A. Maciel; D. Mackin; R. Madar; R. Magaña-Villalba; S. Malik; V. L. Malyshev; Y. Maravin; J. Martínez-Ortega; R. McCarthy; C. L. McGivern; M. M. Meijer; A. Melnitchouk; D. Menezes; P. G. Mercadante; M. Merkin; A. Meyer; J. Meyer; F. Miconi; N. K. Mondal; G. S. Muanza; M. Mulhearn; E. Nagy; M. Naimuddin; M. Narain; R. Nayyar; H. A. Neal; J. P. Negret; P. Neustroev; S. F. Novaes; T. Nunnemann; G. Obrant; J. Orduna; N. Osman; J. Osta; G. J. Otero y Garzón; M. Padilla; A. Pal; N. Parashar; V. Parihar; S. K. Park; J. Parsons; R. Partridge; N. Parua; A. Patwa; B. Penning; M. Perfilov; K. Peters; Y. Peters; K. Petridis; G. Petrillo; P. Pétroff; R. Piegaia; J. Piper; M. -A. Pleier; P. L. M. Podesta-Lerma; V. M. Podstavkov; P. Polozov; A. V. Popov; M. Prewitt; D. Price; N. Prokopenko; S. Protopopescu; J. Qian; A. Quadt; B. Quinn; M. S. Rangel; K. Ranjan; P. N. Ratoff; I. Razumov; P. Renkel; M. Rijssenbeek; I. Ripp-Baudot; F. Rizatdinova; M. Rominsky; A. Ross; C. Royon; P. Rubinov; R. Ruchti; G. Safronov; G. Sajot; P. Salcido; A. Sánchez-Hernández; M. P. Sanders; B. Sanghi; A. S. Santos; G. Savage; L. Sawyer; T. Scanlon; R. D. Schamberger; Y. Scheglov; H. Schellman; T. Schliephake; S. Schlobohm; C. Schwanenberger; R. Schwienhorst; J. Sekaric; H. Severini; E. Shabalina; V. Shary; A. A. Shchukin; R. K. Shivpuri; V. Simak; V. Sirotenko; P. Skubic; P. Slattery; D. Smirnov; K. J. Smith; G. R. Snow; J. Snow; S. Snyder; S. Söldner-Rembold; L. Sonnenschein; K. Soustruznik; J. Stark; V. Stolin; D. A. Stoyanova; M. Strauss; D. Strom; L. Stutte; L. Suter; P. Svoisky; M. Takahashi; A. Tanasijczuk; W. Taylor; M. Titov; V. V. Tokmenin; Y. -T. Tsai; D. Tsybychev; B. Tuchming; C. Tully; L. Uvarov; S. Uvarov; S. Uzunyan; R. Van Kooten; W. M. van Leeuwen; N. Varelas; E. W. Varnes

2011-05-02T23:59:59.000Z

29

Charge asymmetry of top quarks  

E-Print Network (OSTI)

The LHC is a promising machine to discover new physics in the top sector. There are several models that predict the existence of heavy colored resonances decaying to top quarks in the TeV energy range. The production of such resonances might generate a sizable charge asymmetry of top versus antitop quarks. At the Tevatron, a 2 sigma discrepancy with the SM prediction for the forward--backward asymmetry has been found, boosting a renewed interest for this kind of models. We consider a toy model with general flavour dependent couplings of the resonance to quarks, of both vector and axial-vector kind and investigate the possible constraints on the coupling space from the measurement of the asymmetry and the invariant mass distribution at the Tevatron. Then, we define a central asymmetry in a specific kinematic region and investigate its signature at the LHC as well as its statistical significance, for exclusive processes.

Ferrario, Paola

2010-01-01T23:59:59.000Z

30

Charge asymmetry of top quarks  

E-Print Network (OSTI)

The LHC is a promising machine to discover new physics in the top sector. There are several models that predict the existence of heavy colored resonances decaying to top quarks in the TeV energy range. The production of such resonances might generate a sizable charge asymmetry of top versus antitop quarks. At the Tevatron, a 2 sigma discrepancy with the SM prediction for the forward--backward asymmetry has been found, boosting a renewed interest for this kind of models. We consider a toy model with general flavour dependent couplings of the resonance to quarks, of both vector and axial-vector kind and investigate the possible constraints on the coupling space from the measurement of the asymmetry and the invariant mass distribution at the Tevatron. Then, we define a central asymmetry in a specific kinematic region and investigate its signature at the LHC as well as its statistical significance, for exclusive processes.

Paola Ferrario; German Rodrigo

2010-06-29T23:59:59.000Z

31

CDF measurement of the top quark mass in the lepton + jets channel using the multivariate template method  

SciTech Connect

The authors measure the mass of the top quark using 162 pb{sup -1} of data collected by the CDF experiment at FNAL in Run II. The decay chain t{bar t} {yields} bq{bar q}{bar b}lv is studied using a novel technique called the Multivariate Template Method (MTM). Using this technique they obtain a result of M{sub top} = 179.6{sub -6.3}{sup +6.4} {+-} 6.8 GeV/c{sup 2} for the top quark.

Freeman, John; /Fermilab

2004-12-01T23:59:59.000Z

32

Higgs Boson and Top-Quark Masses and Parity-Symmetry Restoration  

E-Print Network (OSTI)

The recent ATLAS and CMS experiments show the first observations of a new particle in the search for the Standard Model Higgs boson at the LHC. We revisit the scenario that high-dimensional operators of fermions must be present due to the theoretical inconsistency of the fundamental cutoff (quantum gravity) with the parity-violating gauge symmetry of the Standard Model. Studying the four-fermion interaction of the third quark family, we show that at an intermediate energy threshold E\\approx 4.27 TeV for the four-fermion coupling being larger than a critical value, the spontaneous symmetry-breaking phase transits to the strong-coupling symmetric phase where composite Dirac fermions form fully preserving the chiral gauge symmetry of the Standard Model and the parity-symmetry is restored. Under this circumstance, we perform the standard analysis of renormalization-group equations of the Standard Model in the spontaneous symmetry-breaking phase. As a result, the Higgs boson mass m_H\\approx 126.7 GeV and top-quark mass m_t\\approx 172.7 GeV are obtained without drastically fine-tuning the four-fermion coupling.

She-Sheng Xue

2013-08-29T23:59:59.000Z

33

Measurement of the Top-Quark Mass in All-Hadronic Decays in p pbar Collisions at CDF II  

E-Print Network (OSTI)

We present a measurement of the top-quark mass, $M_{\\mathrm{top}}$, in the all-hadronic decay channel $t\\bar{t} \\to W^+b W^- \\bar{b} \\to q_1\\bar{q}_2 b q_3 \\bar{q}_4 \\bar{b}$. The analysis is performed using 310 pb$^{-1}$ of $\\sqrt{s}$=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 $M_{\\mathrm{top}}$=177.1 $\\pm$ 4.9 (stat.) $\\pm$ 4.7 (syst.) GeV/$c^2$.

T. Aaltonen

2006-12-12T23:59:59.000Z

34

Observation of the Top Quark  

DOE R&D Accomplishments (OSTI)

Top quark production is observed in{bar p}p collisions at{radical}s= 1.8 TeV at the Fermilab Tevatron. The Collider Detector at Fermilab (CDF) and D{O} observe signals consistent with t{bar t} to WWb{bar b}, but inconsistent with the background prediction by 4.8{sigma} (CDF), 4.6a (D{O}). Additional evidence for the top quark Is provided by a peak in the reconstructed mass distribution. The kinematic properties of the excess events are consistent with the top quark decay. They measure the top quark mass to be 176{plus_minus}8(stat.){plus_minus}10(sys.) GeV/c{sup 2} (CDF), 199{sub -21}{sup+19}(stat.){plus_minus}22(sys.) GeV/c{sup 2} (D{O}), and the t{bar t} production cross section to be 6.8{sub -2.4}{sup+3.6}pb (CDF), 6.4{plus_minus}2.2 pb (D{O}).

Kim, S. B.

1995-08-00T23:59:59.000Z

35

Top quark forward-backward asymmetry in the large invariant mass region  

Science Conference Proceedings (OSTI)

The forward-backward asymmetry in top-pair production that was observed in 2008 gets a boost in a recent CDF publication. Not only has the forward-backward asymmetry been further confirmed, but also distributional preferences are shown. Strikingly, the forward-backward asymmetry is the most sizable in the large M{sub tt} invariant mass region and in the large rapidity difference |{Delta}y| region. Here we used our previously proposed t-channel exchanged W{sup '} boson to explain the new observations. We show that a new particle exchanged in the t channel generically gives rise to such observations. Furthermore, we show that the proposed W{sup '} can be directly produced in association with a top quark at the Tevatron and the LHC. We perform a signal-background analysis and show that such a W{sup '} is readily observed at the Tevatron with a 10 fb{sup -1} luminosity and at the LHC-7 with just a 100 pb{sup -1} luminosity.

Cheung, Kingman [Division of Quantum Phases and Devices, School of Physics, Konkuk University, Seoul 143-701 (Korea, Republic of); Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan (China); Physics Division, National Center for Theoretical Sciences, Hsinchu 300, Taiwan (China); Yuan, Tzu-Chiang [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China)

2011-04-01T23:59:59.000Z

36

Top Quark Production at the Tevatron  

SciTech Connect

The top quark is the most recently discovered of the standard model quarks, and because of its very large mass, studies of the top quark and its interactions are important both as tests of the standard model and searches for new phenomena. In this document, recent results of analyses of top quark production, via both the electroweak and strong interactions, from the CDF and D0 experiments are presented. The results included here utilize a dataset corresponding to up to 6 fb{sup -1} of integrated luminosity, slightly more than half of the dataset recorded by each experiment before the Tevatron was shutdown in September 2011.

Mietlicki, David J.

2011-12-01T23:59:59.000Z

37

Top quark physics at CDF  

SciTech Connect

We present the recent results of top-quark physics using up to 6 fb{sup -1} of p{bar p} collisions analyzed by the CDF collaboration. The large number of top quark events analyzed, of the order of several thousands, allows stringent checks of the standard model predictions. Also, the top quark is widely believed to be a window to new physics. We present the latest measurements of top quark intrinsic properties as well as direct searches for new physics in the top sector.

Potamianos, Karolos

2011-12-01T23:59:59.000Z

38

Measurements of top quark properties at the Tevatron collider  

Science Conference Proceedings (OSTI)

The discovery of the top quark in 1995 opened a whole new sector of investigation of the Standard Model; today top quark physics remains a key priority of the Tevatron program. Some of the measurements of top quark properties, for example its mass, will be a long-standing legacy. The recent evidence of an anomalously large charge asymmetry in top quark events suggests that new physics could couple preferably with top quarks. I will summarize this long chapter of particle physics history and discuss the road the top quark is highlighting for the LHC program.

Margaroli, Fabrizio

2011-05-01T23:59:59.000Z

39

Single top quark measurements with CMS  

E-Print Network (OSTI)

Measurements of single top quark production are presented, performed using CMS data collected in 2011 and 2012 at centre-of-mass energies of 7 and 8 TeV. The cross sections for the electroweak production of single top quarks in the t-channel and in association with W-bosons is measured and the results are used to place constraints on the CKM matrix element |V_tb|.

Jeannine Wagner-Kuhr

2013-02-18T23:59:59.000Z

40

Top Quark Mass Measurement in the Lepton + Jets Channel Using a Matrix Element Method and in situ Jet Energy Calibration  

E-Print Network (OSTI)

A precision measurement of the top quark mass m_t is obtained using a sample of ttbar events from ppbar 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_t and a parameter DJES to calibrate the jet energy scale /in situ/. Using a total of 1087 events, a value of m_t = 173.0 +/- 1.2 GeV/c^2 is measured.

T. Aaltonen et al.

2010-10-21T23:59:59.000Z

Note: This page contains sample records for the topic "top quark mass" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Heavy flavor production and top quark search at hadron colliders  

SciTech Connect

We review heavy flavor production at hadron colliders, with an eye towards the physics of the top quark. Motivation for existence of top, and current status of top search are reviewed. The physics of event simulation at hadron colliders is reviewed. We discuss characteristics of top quark events at p{bar p} colliders that may aid in distinguishing the top quark signal from Standard Model backgrounds, and illustrate various cuts which may be useful for top discovery. Top physics at hadron supercolliders is commented upon, as well as top quark mass measurement techniques. 22 refs., 5 figs.

Baer, H.A.

1991-01-01T23:59:59.000Z

42

Top Quark Properties at the TeVatron  

SciTech Connect

Discovered in 1995 by CDF and D0 at the Fermilab Tevatron collider, the top quark remains interesting to test the Standard Model. Having collected more than 7 fb{sup -1} of integrated luminosity with both experiments until today, several top quark properties have been measured with increasing precision, while other properties have been investigated for the first time. In this article recent measurements of top quark properties from CDF and D0 are presented, using between 1 fb{sup -1} and 4.8 fb{sup -1} of data. In particular, the measurement of the top quark mass, the top quark width, the top antitop mass difference, a check of the electric charge of the top quark, measurements of the top antitop quark spin correlation and W helicity as well as a search for charged Higgs bosons are discussed.

Peters, Yvonne

2011-03-01T23:59:59.000Z

43

Standard Model False Vacuum Inflation: Correlating the Tensor-to-Scalar Ratio to the Top Quark and Higgs Boson masses  

E-Print Network (OSTI)

For a narrow band of values of the top quark and Higgs boson masses, the Standard Model Higgs potential develops a false minimum at energies of about $10^{16}$ GeV, where primordial Inflation could have started in a cold metastable state. A graceful exit to a radiation-dominated era is provided, e.g., by scalar-tensor gravity models. We pointed out that if Inflation happened in this false minimum, the Higgs boson mass has to be in the range $126.0 \\pm 3.5$ GeV, where ATLAS and CMS subsequently reported excesses of events. Here we show that for these values of the Higgs boson mass, the inflationary gravitational wave background has be discovered with a tensor-to-scalar ratio at hand of future experiments. We suggest that combining cosmological observations with measurements of the top quark and Higgs boson masses represents a further test of the hypothesis that the Standard Model false minimum was the source of Inflation in the Universe.

Isabella Masina; Alessio Notari

2011-12-22T23:59:59.000Z

44

Measurement of the top quark mass in $p \\bar{p}$ collisions using events with two leptons  

Science Conference Proceedings (OSTI)

We present a measurement of the top quark mass (m{sub t}) in p{bar p} collisions at {radical}s = 1.96 TeV using t{bar t} events with two leptons (ee, e{mu} or {mu}{mu}) in the final state in 4.3 fb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron collider. We analyze the kinematically underconstrained dilepton events by integrating over the neutrino rapidity distributions. We reduce the dominant systematic uncertainties from jet energy calibration using a correction obtained from t{bar t} {yields} {ell} + jets events. We also correct jets in simulated events to replicate the quark flavor dependence of the jet response in data. In combination with our previous analysis, we measure m{sub t} = 174.0 {+-} 2.4(stat) {+-} 1.4(syst) GeV.

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.; Aoki, Masato; /Fermilab; Askew, Andrew Warren; /Florida State U. /Stockholm U.

2012-01-01T23:59:59.000Z

45

Looking for the Top Quark - Teacher Overview  

NLE Websites -- All DOE Office Websites (Extended Search)

Scientists had evidence for the existence of all of the quarks except for the Top quark. If the Top quark couldn't be found, atomic theory would have to be drastically...

46

Looking for the Top Quark - Lab Pages - My Quarks  

NLE Websites -- All DOE Office Websites (Extended Search)

Teacher Overview VA State Standards of Learning Download this Activity Next Page Looking for the Top Quark - Lab Pages - My Quarks...

47

The Top Quark - 2006 and Beyond  

E-Print Network (OSTI)

We know there is new physics at the electroweak scale, but we don't know what it is. Right now, the top quark is our only window on to this physics. In almost all models of electroweak symmetry breaking, top either couples strongly to new particles or its properties are modified in some way. Top is being studied in detail at the Fermilab Tevatron. Its production cross section has been measured in a variety of channels; its mass has been determined to better than 2%, and can be used to constrain the mass of the Higgs. Top quark decays have been tested and non-standard production mechanisms searched for. Single top production probes the electroweak properties of top, and has not yet been observed; searches are now closing in on this process and it should be seen soon. So far, all of the top quark's properties are consistent with the Standard Model. However, the data still to come at the Tevatron will increase the precision of all these measurements, and the enormous statistics available at the LHC will open up new possibilities such as observation of spin correlations and perhaps even CP violation in the top sector.

John Womersley

2006-04-04T23:59:59.000Z

48

Top Quark Spin Correlations - Theory  

Science Conference Proceedings (OSTI)

The top quark decay width (G{sub F}m{sub t}{sup 3} {approx} 1 GeV) is much larger than the QCD hadronization scale ({Lambda}{sub QCD} {approx} 0.1 GeV) and much larger than the spin decorrelation scale ({Lambda}{sub QCD}{sup 2}/m{sub t} {approx} 0.1 MeV). Therefore, spin correlations in top quark pair production are reflected in angular correlations of the decay products, see [1] and [2].

Parke, Stephen J.; /Fermilab

2012-02-01T23:59:59.000Z

49

Looking for the Top Quark Game  

NLE Websites -- All DOE Office Websites (Extended Search)

In Looking for the Top Quark, each player receives six quarks that they hide on a grid. The players use coordinates to find their opponent's hidden quarks. The first player...

50

Top Quark Production at the LHC  

E-Print Network (OSTI)

Top quark production in proton proton collisions at the Large Hadron Collider (LHC) is reviewed using data collected by the ATLAS and CMS detectors. Most recent results on searches for new physics related to top quark production mechanism are included.

Francesco Spanò; for the ATLAS; CMS collaborations

2011-12-16T23:59:59.000Z

51

Studies of top quark properties at the Tevatron  

Science Conference Proceedings (OSTI)

An overview of the recent measurements of the top quark properties in proton antiproton collisions at {radical}s = 1.96 TeV is presented. These measurements are based on 5.4-8.7 fb{sup -1} of data collected with the D0 and CDF experiments at the Fermilab Tevatron collider. The top quark mass and width measurements, studies of the spin correlation in top quark pair production, W boson helicity measurement, searches for anomalous top quark couplings and Lorentz invariance violation are discussed.

Shary, Viatcheslav

2012-05-01T23:59:59.000Z

52

The search for the top quark  

SciTech Connect

This paper discusses the following topics: top search in the near future, general remarks, top search at HERA, searching for the top quarks at the Z/sup 0/ machines, finding the top at Lep II, top search in UA2, top search in UA1, and top search at CDF. 58 refs., 38 figs.

Barbaro-Galtieri, A.

1989-03-01T23:59:59.000Z

53

Top quark, W-boson and light Higgs  

SciTech Connect

The top quark, the W-boson and the Higg boson form an interesting triptych of elementary particles. In the Standard Model knowing the mass of two of these particles, usually the top quark and W-boson, we can predict the mass of the third, the Higgs boson. Therefore in this proceedings I will primarily cover the following topics, top quark physics, W-boson mass and the light Higgs boson at the proton-antiproton collider at Fermilab, the Tevatron. Other hadron collider topics to be cover in this conference include B-physics, QCD, Electroweak Physics, and Supersymmetry.

Parke, S.

1997-10-01T23:59:59.000Z

54

Studies of top quark production at D0  

Science Conference Proceedings (OSTI)

I present recent results on top quark production in pp collisions at a center of mass energy of 1.96 TeV. The studies were performed by the D0 collaboration using approximately 5 fb{sup -1} of data taken during Run II at the Fermilab Tevatron accelerator. The top quark is the heaviest known elementary particle and completes the quark sector of the three-generation structure of the standard model (SM). It differs from the other quarks not only by its much larger mass, but also by its lifetime which is too short to build hadronic bound states. The SM predicts that top quarks are created via two independent production mechanisms at hadron colliders. The primary mode, in which a t{bar t} pair is produced from a gtt vertex via the strong interaction, was used by the D0 and CDF collaborations to establish the existence of the top quark in 1995. The second production mode of top quarks at hadron colliders is the electroweak production of a single top quark from a Wtb vertex. The predicted cross section for single top quark production is about half that of t{bar t} pairs but the signal-to-background ratio is much worse; observation of single top quark production has therefore until recently been impeded by its low rate and difficult background environment compared to the top pair production. In the following sections I will present results for the measurement of the t{bar t} pair and the single top quark production cross section using respectively 5.3 fb{sup -1} and 5.4 fb{sup -1} of data taken by the D0 experiment.

Gerber, Cecilia E.; /Illinois U., Chicago

2011-07-01T23:59:59.000Z

55

Summary of the session on the top quark  

Science Conference Proceedings (OSTI)

The CDF and D0 experiments at the Fermilab Tevatron showed recent results on the production and properties of the top quark. The CMS and ATLAS experiments presented first observations of top events at the LHC. Prospects for the top physics at the LHC over the next few years were discussed. CDF and D0 have made remarkable progress in detemerining the properties of the top quark, which so far, conforms to the expectations of the SM. The sophisticated methods they have developed form the basis of the exploration that is now starting at the LHC. New methods, such as the use of boosted top quark signatures, will be necessary to realize fully the potential of the LHC for finding new high mass particles decaying to top and for searching for deviations from the SM. Prospects for the future of top quark physics are very bright.

Butler, Joel N.; /Fermilab

2011-01-01T23:59:59.000Z

56

Measurements of Top Quark Properties at the Tevatron  

SciTech Connect

The top quark is the most recently discovered of the standard model quarks, and studies of its properties are important tests of the standard model. Many measurements of top properties have been produced by the CDF and D0 collaborations, which study top quarks produced in p{bar p} collisions at the Fermilab Tevatron with a center-of-mass energy {radical}s = 1.96 TeV. We describe recent results from top properties measurements at the Tevatron using datasets corresponding to integrated luminosities up to 8.7 fb{sup -1}.

Mietlicki, David J.; /Michigan U.

2012-04-01T23:59:59.000Z

57

Top Mass Measurements at the Tevatron  

Science Conference Proceedings (OSTI)

First observed in 1995, the top quark is the third-generation up-type quark of the standard model of particle physics (SM). The CDF and D0 collaborations have analyzed many t{bar t} events produced by the Tevatron collider, studying many properties of the top quark. Among these, the mass of the top quark is a fundamental parameter of the SM, since its value constrains the mass of the yet to be observed Higgs boson. The analyzed events were used to measure the mass of the top quark m{sub t} {approx_equal} 173.2 GeV/c{sup 2} with an uncertainty of less than 1 GeV/c{sup 2}. We report on the latest top mass measurements at the Tevatron, using up to 6 fb{sup -1} of data for each experiment.

Potamianos, Karolos; /Purdue U.

2012-01-01T23:59:59.000Z

58

Single Top Quark Production at the Tevatron  

E-Print Network (OSTI)

While the heaviest known elementary particle, the top quark, has been discovered in 1995 by the CDF and D0 collaborations in ttbar events, it took 14 more years until the observation of single top quark production. In this article, we discuss recent studies of single top quark production by the CDF and D0 collaborations at the Tevatron. In particular, we present the measurement of single top quark s- and t-channel production combined, the first observation of t-channel production, the simultaneous measurement of s- and t-channel production cross sections as well as the extraction of the CMK matrix element |Vtb}|.

Yvonne Peters; for the CDF; D0 Collaborations

2012-10-26T23:59:59.000Z

59

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

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.

Kroeninger, Kevin Alexander; /Bonn U.

2004-04-01T23:59:59.000Z

60

Observation of Single Top Quark Production  

SciTech Connect

The author reports on the observation of electroweak production of single top quarks in p{bar p} collisions at {radical}s = 1.96 Tev using 2.3 fb{sup -1} of data collected with the D0 detector at the fermilab Tevatron Collider. Using events containing an isolated electron or muon, missing transverse energy, two, three or four jets, with one or two of them identified as originating from the fragmentation of a b quark, the measured cross section for the process p{bar p} {yields} tb + X, tqb + X is 3.94 {+-} 0.88 pb (for a top quark mass of 170 GeV). the probability to measure a cross section at this value or higher in the absence of signal is 2.5 x 10{sup -7}, corresponding to a 5.0 standard deviation significance. Using the same dataset, the measured cross sections for the t- and the s-channel processes when determined simultaneously with no assumption on their relative production rate are 3.14{sub -0.80}{sup +0.94} pb and 1.05 {+-} 0.81 pb respectively, consistent with standard model expectations. The measured t-channel cross section has a significance of 4.8 standard deviations, representing the first evidence for the production of an individual single top process to be detected.

Gerber, Cecilia E.; /Illinois U., Chicago

2009-09-01T23:59:59.000Z

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61

Top quark spin and $Htb$ interaction in charged Higgs and top quark associated production at LHC  

E-Print Network (OSTI)

We study the charged Higgs production at LHC via its associated production with top quark. The kinematic cuts are optimized to suppress the background processes so that the reconstruction of the charged Higgs and top quark is possible. The angular distributions with respect to top quark spin are explored to study the $Htb$ interaction at LHC.

Xue Gong; Zong-Guo Si; Shuo Yang; Ya-juan Zheng

2012-10-29T23:59:59.000Z

62

Measurements of the Top Quark at the Tevatron Collider  

SciTech Connect

The authors present recent preliminary measurements of the top-antitop pair production cross section and determinations of the top quark pole mass, performed using the data collected by the CDF and D0 Collaborations at the Tevatron Collider. In the lepton plus jets final state, with semileptonic B decay, the pair production cross section has now been measured at CDF using {approx} 760 pb{sup -1} of proton-antiproton collisions at a center-of-mass energy of {radical}s = 1.96 TeV. A measurement of the production cross section has also been made with {approx} 1 fb{sup -1} of data in the all-jets final state by the CDF Collaboration. The mass of the top quark has now been measured using {approx} 1 fb{sup -1} of collision data using all decay channels of the top quark pair, yielding the most precise measurements of the top mass to date.

Cerrito, Lucio; /Queen Mary, U. of London

2007-01-01T23:59:59.000Z

63

Observation of $t$-channel electroweak top quark production  

SciTech Connect

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.

Triplett, Nathan; /Iowa State U.

2011-04-01T23:59:59.000Z

64

Top Quark Mass Measurement in the Lepton + Jets Channel Using a Matrix Element Method and \\textit{in situ} Jet Energy Calibration  

SciTech Connect

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.

Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.; /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U.; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Apresyan, A.; /Purdue U.; Arisawa, T.; /Waseda U. /Dubna, JINR

2010-10-01T23:59:59.000Z

65

Determination of the width of the top quark  

E-Print Network (OSTI)

We extract the total width of the top quark, Gamma_t, from the partial decay width Gamma(t -> W b) measured using the t-channel cross section for single top quark production and from the branching fraction B(t -> W b) measured in ttbar events using up to 2.3 fb^-1 of integrated luminosity collected by the D0 Collaboration at the Tevatron ppbar Collider. The result is Gamma_t = 1.99 +0.69 -0.55 GeV, which translates to a top-quark lifetime of tau_t = (3.3 +1.3 -0.9) x 10^-25 s. Assuming a high mass fourth generation b' quark and unitarity of the four-generation quark-mixing matrix, we set the first upper limit on |Vtb'| < 0.63 at 95% C.L.

V. M. Abazov; B. Abbott; M. Abolins; B. S. Acharya; M. Adams; T. Adams; G. D. Alexeev; G. Alkhazov; A. Altona; G. Alverson; G. A. Alves; L. S. Ancu; M. Aoki; Y. Arnoud; M. Arov; A. Askew; B. \\degAsman; O. Atramentov; C. Avila; J. BackusMayes; F. Badaud; L. Bagby; B. Baldin; D. V. Bandurin; S. Banerjee; E. Barberis; P. Baringer; J. Barreto; J. F. Bartlett; U. Bassler; V. Bazterra; S. Beale; A. Bean; M. Begalli; M. Begel; C. Belanger-Champagne; L. Bellantoni; S. B. Beri; G. Bernardi; R. Bernhard; I. Bertram; M. Besan?con; R. Beuselinck; V. A. Bezzubov; P. C. Bhat; V. Bhatnagar; G. Blazey; S. Blessing; K. Bloom; A. Boehnlein; D. Boline; T. A. Bolton; E. E. Boos; G. Borissov; T. Bose; A. Brandt; O. Brandt; R. Brock; G. Brooijmans; A. Bross; D. Brown; J. Brown; X. B. Bu; D. Buchholz; M. Buehler; V. Buescher; V. Bunichev; S. Burdinb; T. H. Burnett; C. P. Buszello; B. Calpas; E. Camacho-P?erez; M. A. Carrasco-Lizarraga; B. C. K. Casey; H. Castilla-Valdez; S. Chakrabarti; D. Chakraborty; K. M. Chan; A. Chandra; G. Chen; S. Chevalier-Th?ery; D. K. Cho; S. W. Cho; S. Choi; B. Choudhary; T. Christoudias; S. Cihangir; D. Claes; J. Clutter; M. Cooke; W. E. Cooper; M. Corcoran; F. Couderc; M. -C. Cousinou; A. Croc; D. Cutts; M. ?Cwiok; A. Das; G. Davies; K. De; S. J. de Jong; E. De La Cruz-Burelo; F. D?eliot; M. Demarteau; 47 R. Demina; D. Denisov; S. P. Denisov; S. Desai; K. DeVaughan; H. T. Diehl; M. Diesburg; A. Dominguez; T. Dorland; A. Dubey; L. V. Dudko; D. Duggan; A. Duperrin; S. Dutt; A. Dyshkant; M. Eads; D. Edmunds; J. Ellison; V. D. Elvira; Y. Enari; S. Eno; H. Evans; A. Evdokimov; V. N. Evdokimov; G. Facini; T. Ferbel; F. Fiedler; F. Filthaut; W. Fisher; H. E. Fisk; M. Fortner; H. Fox; S. Fuess; T. Gadfort; A. Garcia-Bellido; V. Gavrilov; P. Gay; W. Geist; W. Geng; D. Gerbaudo; C. E. Gerber; Y. Gershtein; G. Ginther; G. Golovanov; A. Goussiou; P. D. Grannis; S. Greder; H. Greenlee; Z. D. Greenwood; E. M. Gregores; G. Grenier; Ph. Gris; J. -F. Grivaz; A. Grohsjean; S. Gr?unendahl; M. W. Gr?unewald; F. Guo; J. Guo; G. Gutierrez; P. Gutierrez; A. Haasc; S. Hagopian; J. Haley; L. Han; K. Harder; A. Harel; J. M. Hauptman; J. Hays; T. Head; T. Hebbeker; D. Hedin; H. Hegab; A. P. Heinson; U. Heintz; C. Hensel; I. Heredia-De La Cruz; K. Herner; G. Hesketh; M. D. Hildreth; R. Hirosky; T. Hoang; J. D. Hobbs; B. Hoeneisen; M. Hohlfeld; S. Hossain; Z. Hubacek; N. Huske; V. Hynek; I. Iashvili; R. Illingworth; A. S. Ito; S. Jabeen; M. Jaffr?e; S. Jain; D. Jamin; R. Jesik; K. Johns; M. Johnson; D. Johnston; A. Jonckheere; P. Jonsson; J. Joshi; A. Justed; K. Kaadze; E. Kajfasz; D. Karmanov; P. A. Kasper; I. Katsanos; R. Kehoe; S. Kermiche; N. Khalatyan; A. Khanov; A. Kharchilava; Y. N. Kharzheev; D. Khatidze; M. H. Kirby; J. M. Kohli; A. V. Kozelov; J. Kraus; A. Kumar; A. Kupco; T. Kur?ca; V. A. Kuzmin; J. Kvita; S. Lammers; G. Landsberg; P. Lebrun; H. S. Lee; S. W. Lee; W. M. Lee; J. Lellouch; L. Li; Q. Z. Li; S. M. Lietti; J. K. Lim; D. Lincoln; J. Linnemann; V. V. Lipaev; R. Lipton; Y. Liu; Z. Liu; A. Lobodenko; M. Lokajicek; P. Love; H. J. Lubatti; R. Luna-Garciae; A. L. Lyon; A. K. A. Maciel; D. Mackin; R. Madar; R. Maga?na-Villalba; S. Malik; V. L. Malyshev; Y. Maravin; J. Mart?\\inez-Ortega; R. McCarthy; C. L. McGivern; M. M. Meijer; A. Melnitchouk; D. Menezes; P. G. Mercadante; M. Merkin; A. Meyer; J. Meyer; N. K. Mondal; G. S. Muanza; M. Mulhearn; E. Nagy; M. Naimuddin; M. Narain; R. Nayyar; H. A. Neal; J. P. Negret; P. Neustroev; S. F. Novaes; T. Nunnemann; G. Obrant; J. Orduna; N. Osman; J. Osta; G. J. Otero y Garz?on; 1 M. Owen; M. Padilla; M. Pangilinan; N. Parashar; V. Parihar; S. K. Park; J. Parsons; R. Partridgec; N. Parua; A. Patwa; B. Penning; M. Perfilov; K. Peters; Y. Peters; G. Petrillo; P. P?etroff; R. Piegaia; J. Piper; M. -A. Pleier; P. L. M. Podesta-Lermaf; V. M. Podstavkov; M. -E. Pol; P. Polozov; A. V. Popov; M. Prewitt; D. Price; S. Protopopescu; J. Qian; A. Quadt; B. Quinn; M. S. Rangel; K. Ranjan; P. N. Ratoff; I. Razumov; P. Renkel; P. Rich; M. Rijssenbeek; I. Ripp-Baudot; F. Rizatdinova; M. Rominsky; C. Royon; P. Rubinov; R. Ruchti; G. Safronov; G. Sajot; A. S?anchez-Hern?andez; M. P. Sanders; B. Sanghi; A. S. Santos; G. Savage; L. Sawyer; T. Scanlon; R. D. Schamberger; Y. Scheglov; H. Schellman; T. Schliephake; S. Schlobohm; C. Schwanenberger; R. Schwienhorst; J. Sekaric; H. Severini; E. Shabalina; V. Shary; A. A. Shchukin; R. K. Shivpuri; V. Simak; V. Sirotenko; P. Skubic; P. Slattery; D. Smirnov; K. J. Smith; G. R. Snow; J. Snow; S. Snyder; S. S?oldner-Rembold; L. Sonnenschein; A. Sopczak; M. Sosebee; K. Soustruznik; B. Spurlock; J. Stark; V. Stolin; D. A. Stoyanova; E. Strauss; M. Strauss; D. Strom; L. Stutte; P. Svoisky; M. Takahashi; A. Tanasijczuk; W. Taylor; M. Titov; V. V. Tokmenin; D. Tsybychev; B. Tuchming; C. Tully; P. M. Tuts; L. Uvarov

2010-09-28T23:59:59.000Z

66

Press Pass - Press Release - Single top quark  

NLE Websites -- All DOE Office Websites (Extended Search)

9-04 9-04 March 9, 2009 For immediate release Media Contacts: Judy Jackson, Fermilab, +1-630-840-3351, jjackson@fnal.gov Kurt Riesselmann, Fermilab, +1-630-840-3351, kurtr@fnal.gov Graphics and photos are available at: http://www.fnal.gov/pub/presspass/images/Single-Top-Quark-2009.html Fermilab collider experiments discover rare single top quark Batavia, Ill.-Scientists of the CDF and DZero collaborations at the Department of Energy's Fermi National Accelerator Laboratory have observed particle collisions that produce single top quarks. The discovery of the single top confirms important parameters of particle physics, including the total number of quarks, and has significance for the ongoing search for the Higgs particle at Fermilab's Tevatron, currently the world's most powerful operating particle accelerator.

67

Commissioning ATLAS and CMS with top quarks  

E-Print Network (OSTI)

The large ttbar production cross-section at the LHC suggests the use of top quark decays to calibrate several critical parts of the detectors, such as the trigger system, the jet energy scale and b-tagging.

B. S. Acharya; F. Cavallari; G. Corcella; R. Di Sipio; G. Petrucciani

2008-05-25T23:59:59.000Z

68

Single top quark production at D0  

SciTech Connect

Updates of electroweak single top quark production measurements by the D0 collaboration are presented using 5.4 fb{sup -1} of proton-antiproton collision data from the Tevatron at Fermilab. Measurements of the t-channel, s-channel and combined single top quark production cross section are presented, including an updated lower limit on the CKM matrix element |V{sub tb}|. Also reported are results from searches for gluon-quark flavor-changing neutral currents and W' boson production.

Schwienhorst, Reinhard; /Michigan State U.

2011-09-01T23:59:59.000Z

69

Evidence for production of single top quarks  

SciTech Connect

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.

Abazov, V.M.; /Dubna, JINR; Abbott, B.; /Oklahoma U.; Abolins, M.; /Michigan State U.; Acharya, B.S.; /Tata Inst.; Adams, M.; /Illinois U., Chicago; Adams, T.; /Florida State U.; Aguilo, E.; /Simon Fraser U.; Ahn, S.H.; /Korea U., KODEL; Ahsan, M.; /Kansas State U.; Alexeev, G.D.; /Dubna, JINR; Alkhazov, G.; /St. Petersburg, INP /Michigan U.

2008-03-01T23:59:59.000Z

70

A Measurement of the Top Quark Mass in 1.96 TeV Proton-Antiproton Collisions Using a Novel Matrix Element Method  

SciTech Connect

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}.

CDF Collaboration; Freeman, John; Freeman, John

2007-09-30T23:59:59.000Z

71

A measurement of the top quark mass in 1.96 TeV proton-antiproton collisions using a novel matrix element method  

SciTech Connect

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 elements techniques, the method involves an integration using the Standard Model matrix element for tt 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}.

Freeman, John C.; /LBL, Berkeley

2007-12-01T23:59:59.000Z

72

Improved determination of the width of the top quark  

SciTech Connect

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.

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.

2012-05-04T23:59:59.000Z

73

Measurements of the Properties of the Top Quark  

Science Conference Proceedings (OSTI)

We review recent measurements of the properties of the top quark: the decay width of the top quark, of spin correlations between the top and the antitop quarks in t{bar t} production, the W boson helicity in top decays, the strong colour flow in t{bar t} events, and the asymmetry of t{bar t} production due to the strong colour charge. The measurements are performed on data samples of up to 5.4 fb{sup -1} of integrated luminosity acquired by the CDF and D0 collaborations in Run II of the Fermilab Tevatron p{bar p} collider at a centre-of-mass energy of {radical}s = 1.96 TeV.

Brandt, Oleg

2011-08-01T23:59:59.000Z

74

Uncovering the single top: observation of electroweak top quark production  

Science Conference Proceedings (OSTI)

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.

Benitez, Jorge Armando; /Michigan State U.

2009-08-01T23:59:59.000Z

75

Top Quark Physics at the LHC  

E-Print Network (OSTI)

An overview of the prospects of top quark physics at the LHC is presented. The ATLAS and the CMS detectors are about to produce a large amount of data with high top quark contents from the LHC proton-proton collisions. A wide variet y of physics analyses is planned in both experiments, and a number of useful insights have already been obtained regarding their detector performance and physics potential. This summary is based on the talk presented at the Hadron C ollider Physics Symposium 2008, Galena, Illinois, May 27-31, 2008.

Akira Shibata

2008-07-31T23:59:59.000Z

76

An Improved determination of the width of the top quark  

SciTech Connect

We present an improved determination of the total width of the top quark, {Lambda}{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 {Lambda}{sub t} is extracted from the partial decay width {Lambda}(t {yields} Wb) and the branching fraction {Beta}(t {yields} Wb). {Lambda}(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 {Lambda}{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 CKM 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.

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.; Aoki, Masato; /Fermilab; Askew, Andrew Warren; /Florida State U. /Stockholm U.

2012-01-01T23:59:59.000Z

77

Top quark pair production in proton anti-proton collisions  

Science Conference Proceedings (OSTI)

This thesis presents a measurement of the t{bar t} cross section in the all-jets channel, measured in p{bar p} collisions at a center of mass energy of 1.96 TeV, using data collected with the D0 detector. The dataset used for this analysis has an integrated luminosity equivalent to L = 162.5 {+-} 10.6 pb{sup -1}. A t{bar t} cross section measurement is a test of the Standard Model predictions for heavy quark production, and the first step towards measurements of the mass and other properties of the top quark. The presented measurement of the cross section for the process p{bar p} {yields} t{bar t} uses the decay channel where both top quarks decay to quarks. The top quark first decays to a b quark and a W boson, and then, for this particular channel, the W boson decays hadronically. Hence, events with six energetic quarks are expected, which ideally leads to events with six jets. These so called all-jets events have a significantly larger branching fraction than other t{bar t} decay channels. The large branching fraction in the all-jets channel means that a significant sample of t{bar t} candidates can be extracted, which can subsequently be used for studies of top quark properties, like the top mass. The background, multijet production through Quantum Chromo Dynamics (QCD) has a cross section three to four orders of magnitude larger than expected for t{bar t} production. The analysis presented in this thesis uses the decay vertices of long-lived b-flavored mesons to identify the b jets. With the silicon detector installed at the start of Run 2 of the Tevatron, the D0 experiment is now able to use this method for b identification. The presence of b quarks in the event makes it possible to reduce the background to a few percent of the original sample, while only rejecting around 45% of the t{bar t} content in the sample.

Blekman, Freya; /NIKHEF, Amsterdam

2005-04-01T23:59:59.000Z

78

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

Science Conference Proceedings (OSTI)

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.

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

2011-08-15T23:59:59.000Z

79

Kinematics of Top Quark Final States: A Snowmass White Paper  

E-Print Network (OSTI)

This is the summary report of the Top Quark Kinematics working group prepared for Snowmass 2013. We survey the current state of theoretical predictions for top pair differential distributions, in both boosted and un-boosted regimes, and present an overview of uncertainties and prospects for top spin correlations. We study the prospects for measuring the inclusive SM top pair production asymmetry AFC at LHC 14 as a function of systematic error, and show that some improvement over current systematic uncertainties, as customarily handled, is required for observing a SM-size asymmetry. Cuts on top pair invariant mass and rapidity do not substantially alter this conclusion. We summarize the conclusions of contributed studies on alternate LHC measurements of the ttbar production asymmetry, in ttbar+jet final states and in forward top production at LHCb, both of which show good prospects for observing SM-size asymmetries in 50 fb-1 of data at LHC14.

Andreas Jung; Markus Schulze; Jessie Shelton

2013-09-11T23:59:59.000Z

80

Determination of the width of the top quark  

SciTech Connect

We extract the total width of the top quark, {Lambda}{sub t}, from the partial decay width {Lambda}(t {yields} Wb) measured using the t-channel cross section for single top quark production and from the branching fraction B(t {yields} Wb) measured in t{bar t} events using up to 2.3 fb{sup -1} of integrated luminosity collected by the D0 Collaboration at the Tevatron p{bar p} Collider. The result is {Lambda}{sub t} = 1.99{sub -0.55}{sup +0.69} GeV, which translates to a top-quark lifetime of {tau}{sub t} = (3.3{sub -0.9}{sup +1.3}) x 10{sup -25} s. Assuming a high mass fourth generation b{prime} quark and unitarity of the four-generation quark-mixing matrix, we set the first upper limit on |V{sub tb{prime}}| < 0.63 at 95% C.L.

Abazov, Victor Mukhamedovich; /Dubna, JINR; Abbott, Braden Keim; /Oklahoma U.; Abolins, Maris A.; /Michigan State 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 /Nijmegen U.

2010-09-01T23:59:59.000Z

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81

Top-quark asymmetry and the search for a light hadronic resonance in association with a single top quark  

Science Conference Proceedings (OSTI)

The exchange of a light t-channel flavor-changing gauge boson, V', with mass {approx}m{sub top} remains a leading explanation for the anomalous forward-backward asymmetry in top-quark production at the Tevatron. Unlike other ideas, including heavier t-channel mediators, the light V' model is not easily seen in the m{sub tt} distribution. We advocate a more promising strategy. While current analyses at hadron colliders may not be sensitive, we propose searching for a jj resonance in association with single top that may allow discovery in existing data. Deviations in the lepton charge asymmetry in this sample should also be present.

Jung, Sunghoon; Pierce, Aaron [Michigan Center for Theoretical Physics, Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States); Wells, James D. [Michigan Center for Theoretical Physics, Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States); CERN Theoretical Physics (PH-TH), CH-1211 Geneva 23 (Switzerland)

2011-11-01T23:59:59.000Z

82

Measurement of the top quark mass with the dynamical likelihood method using lepton plus jets events with b-tags in p anti-p collisions at s**(1/2) = 1.96-TeV  

SciTech Connect

This report describes a measurement of the top quark mass, M{sub top}, with the dynamical likelihood method (DLM) using the CDF II detector at the Fermilab Tevatron. The Tevatron produces top/anti-top (t{bar t}) pairs in p{bar p} collisions at a center-of-mass energy of 1.96 TeV. The data sample used in this analysis was accumulated from March 2002 through August 2004, which corresponds to an integrated luminosity of 318 pb{sup -1}. They use the t{bar t} candidates in the ''lepton+jets'' decay channel, requiring at least one jet identified as a b quark by finding an displaced secondary vertex. The DLM defines a likelihood for each event based on the differential cross section as a function of M{sub top} per unit phase space volume of the final partons, multiplied by the transfer functions from jet to parton energies. The method takes into account all possible jet combinations in an event, and the likelihood is multiplied event by event to derive the top quark mass by the maximum likelihood method. Using 63 t{bar t} candidates observed in the data, with 9.2 events expected from background, they measure the top quark mass to be 173.2{sub -2.4}{sup +2.6}(stat.) {+-} 3.2(syst.) GeV/c{sup 2}, or 173.2{sub -4.0}{sup +4.1} GeV/c{sup 2}.

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 /Bologna U. /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara

2005-12-01T23:59:59.000Z

83

Top Quark Production Cross Section at the Tevatron  

SciTech Connect

An overview of the preliminary results of the top quark pair production cross section measurements at a center-of-mass energy of 1.96 TeV carried out by the CDF and D0 collaborations is presented. The data samples used for the analyses are collected in the current Tevatron run and correspond to an integrated luminosity from 360 pb{sup -1} up to 760 pb{sup -1}.

Shabalina, E.; /Chicago U.

2006-05-01T23:59:59.000Z

84

Single top quark production and Vtb at the Tevatron  

SciTech Connect

Single top quark production via the electroweak interaction was observed by the D0 and CDF collaborations at the Tevatron proton-antiproton collider at Fermilab. Multivariate analysis techniques are employed to extract the small single top quark signal. The combined Tevatron cross section is 2.76{sub -0.47}{sup +0.58} pb. This corresponds to a lower limit on the CKM matrix element |V{sub tb}| of 0.77. Also reported are measurements of the t-channel cross section, the top quark polarization in single top quark events, and limits on gluon-quark flavor-changing neutral currents and W{prime} boson production.

Schwienhorst, Reinhard; /Michigan State U.

2010-09-01T23:59:59.000Z

85

Search of anomalous $Wtb$ couplins in single top quark prodution at D0  

SciTech Connect

The large mass of the top quark, close to the electroweak symmetry-breaking scale, makes it a good candidate for probing physics beyond the Standard Model, including possible anomalous couplings. D0 has made measurements of single top quark production using 5.4 fb{sup -1} of integrated luminosity. We examine the data to study the Lorentz structure of the Wtb coupling. We find that the data prefer the left-handed vector coupling and set upper limits on the anomalous couplings. In 2009, the electroweak single top quark production was observed by the D0 and CDF collaborations. Electroweak production of top quarks at the Tevatron proceeds mainly via the decay of a time-like virtual W boson accompanied by a bottom quark in the s-channel (tb = t{bar b} + {bar t}b), or via the exchange of a space-like virtual W boson between a light quark and a bottom quark in the t-channel (tqb = tq{bar b} + {bar t}qb, where q refers to the light quark). For a top quark mass of 172.5 GeV, The Standard Model (SM) prediction of single top production rate at next-to-leading order with soft-gluon contributions at next-to-next-to-leading order are 1.04 {+-} 0.04 pb (s-channel) and 2.26 {+-} 0.12 pb (t-channel). The large mass of the top quark implies that it has large couplings to the electroweak symmetry breaking sector of the SM and may have non-standard interactions with the weak gauge bosons. Single top quark production provides a unique probe to study the interactions of the top quark with the W boson.

Joshi, Jyoti; Beri, Suman; /Panjab U.

2011-12-01T23:59:59.000Z

86

Search for pair production of the scalar top quark in the electron-muon final state  

E-Print Network (OSTI)

We report the result of a search for the pair production of the lightest supersymmetric partner of the top quark ($\\tilde{t}_1$) 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$^{-1}$. The scalar top quarks are assumed to decay into a $b$ quark, a charged lepton, and a scalar neutrino ($\\tilde{\

V. M. Abazov; B. Abbott; M. Abolins; B. S. Acharya; M. Adams; T. Adams; G. D. Alexeev; G. Alkhazov; A. Altona; G. Alverson; G. A. Alves; L. S. Ancu; M. Aoki; Y. Arnoud; M. Arov; A. Askew; B. Åsman; O. Atramentov; C. Avila; J. BackusMayes; F. Badaud; L. Bagby; B. Baldin; D. V. Bandurin; S. Banerjee; E. Barberis; P. Baringer; J. Barreto; J. F. Bartlett; U. Bassler; V. Bazterra; S. Beale; A. Bean; M. Begalli; M. Begel; C. Belanger-Champagne; L. Bellantoni; S. B. Beri; G. Bernardi; R. Bernhard; I. Bertram; M. Besançon; R. Beuselinck; V. A. Bezzubov; P. C. Bhat; V. Bhatnagar; G. Blazey; S. Blessing; K. Bloom; A. Boehnlein; D. Boline; T. A. Bolton; E. E. Boos; G. Borissov; T. Bose; A. Brandt; O. Brandt; R. Brock; G. Brooijmans; A. Bross; D. Brown; J. Brown; X. B. Bu; D. Buchholz; M. Buehler; V. Buescher; V. Bunichev; S. Burdinb; T. H. Burnett; C. P. Buszello; B. Calpas; E. Camacho-Pérez; M. A. Carrasco-Lizarraga; B. C. K. Casey; H. Castilla-Valdez; S. Chakrabarti; D. Chakraborty; K. M. Chan; A. Chandra; G. Chen; S. Chevalier-Théry; D. K. Cho; S. W. Cho; S. Choi; B. Choudhary; T. Christoudias; S. Cihangir; D. Claes; J. Clutter; M. Cooke; W. E. Cooper; M. Corcoran; F. Couderc; M. -C. Cousinou; A. Croc; D. Cutts; M. ?wiok; A. Das; G. Davies; K. De; S. J. de Jong; E. De La Cruz-Burelo; F. Déliot; M. Demarteau; 47 R. Demina; D. Denisov; S. P. Denisov; S. Desai; K. DeVaughan; H. T. Diehl; M. Diesburg; A. Dominguez; T. Dorland; A. Dubey; L. V. Dudko; D. Duggan; A. Duperrin; S. Dutt; A. Dyshkant; M. Eads; D. Edmunds; J. Ellison; V. D. Elvira; Y. Enari; S. Eno; H. Evans; A. Evdokimov; V. N. Evdokimov; G. Facini; T. Ferbel; F. Fiedler; F. Filthaut; W. Fisher; H. E. Fisk; M. Fortner; H. Fox; S. Fuess; T. Gadfort; A. Garcia-Bellido; V. Gavrilov; P. Gay; W. Geist; W. Geng; D. Gerbaudo; C. E. Gerber; Y. Gershtein; G. Ginther; G. Golovanov; A. Goussiou; P. D. Grannis; S. Greder; H. Greenlee; Z. D. Greenwood; E. M. Gregores; G. Grenier; Ph. Gris; J. -F. Grivaz; A. Grohsjean; S. Grünendahl; M. W. Grünewald; F. Guo; J. Guo; G. Gutierrez; P. Gutierrez; A. Haasc; S. Hagopian; J. Haley; L. Han; K. Harder; A. Harel; J. M. Hauptman; J. Hays; T. Head; T. Hebbeker; D. Hedin; H. Hegab; A. P. Heinson; U. Heintz; C. Hensel; I. Heredia-De La Cruz; K. Herner; G. Hesketh; M. D. Hildreth; R. Hirosky; T. Hoang; J. D. Hobbs; B. Hoeneisen; M. Hohlfeld; S. Hossain; Z. Hubacek; N. Huske; V. Hynek; I. Iashvili; R. Illingworth; A. S. Ito; S. Jabeen; M. Jaffré; S. Jain; D. Jamin; R. Jesik; K. Johns; M. Johnson; D. Johnston; A. Jonckheere; P. Jonsson; J. Joshi; A. Justed; K. Kaadze; E. Kajfasz; D. Karmanov; P. A. Kasper; I. Katsanos; R. Kehoe; S. Kermiche; N. Khalatyan; A. Khanov; A. Kharchilava; Y. N. Kharzheev; D. Khatidze; M. H. Kirby; J. M. Kohli; A. V. Kozelov; J. Kraus; A. Kumar; A. Kupco; T. Kur?a; V. A. Kuzmin; J. Kvita; S. Lammers; G. Landsberg; P. Lebrun; H. S. Lee; S. W. Lee; W. M. Lee; J. Lellouch; L. Li; Q. Z. Li; S. M. Lietti; J. K. Lim; D. Lincoln; J. Linnemann; V. V. Lipaev; R. Lipton; Y. Liu; Z. Liu; A. Lobodenko; M. Lokajicek; P. Love; H. J. Lubatti; R. Luna-Garciae; A. L. Lyon; A. K. A. Maciel; D. Mackin; R. Madar; R. Magaña-Villalba; S. Malik; V. L. Malyshev; Y. Maravin; J. Martínez-Ortega; R. McCarthy; C. L. McGivern; M. M. Meijer; A. Melnitchouk; D. Menezes; P. G. Mercadante; M. Merkin; A. Meyer; J. Meyer; N. K. Mondal; G. S. Muanza; M. Mulhearn; E. Nagy; M. Naimuddin; M. Narain; R. Nayyar; H. A. Neal; J. P. Negret; P. Neustroev; S. F. Novaes; T. Nunnemann; G. Obrant; J. Orduna; N. Osman; J. Osta; G. J. Otero y Garzón; M. Owen; M. Padilla; M. Pangilinan; N. Parashar; V. Parihar; S. K. Park; J. Parsons; R. Partridgec; N. Parua; A. Patwa; B. Penning; M. Perfilov; K. Peters; Y. Peters; G. Petrillo; P. Pétroff; R. Piegaia; J. Piper; M. -A. Pleier; P. L. M. Podesta-Lermaf; V. M. Podstavkov; M. -E. Pol; P. Polozov; A. V. Popov; M. Prewitt; D. Price; S. Protopopescu; J. Qian; A. Quadt; B. Quinn; M. S. Rangel; K. Ranjan; P. N. Ratoff; I. Razumov; P. Renkel; P. Rich; M. Rijssenbeek; I. Ripp-Baudot; F. Rizatdinova; M. Rominsky; C. Royon; P. Rubinov; R. Ruchti; G. Safronov; G. Sajot; A. Sánchez-Hernández; M. P. Sanders; B. Sanghi; A. S. Santos; G. Savage; L. Sawyer; T. Scanlon; R. D. Schamberger; Y. Scheglov; H. Schellman; T. Schliephake; S. Schlobohm; C. Schwanenberger; R. Schwienhorst; J. Sekaric; H. Severini; E. Shabalina; V. Shary; A. A. Shchukin; R. K. Shivpuri; V. Simak; V. Sirotenko; P. Skubic; P. Slattery; D. Smirnov; K. J. Smith; G. R. Snow; J. Snow; S. Snyder; S. Söldner-Rembold; L. Sonnenschein; A. Sopczak; M. Sosebee; K. Soustruznik; B. Spurlock; J. Stark; V. Stolin; D. A. Stoyanova; E. Strauss; M. Strauss; D. Strom; L. Stutte; P. Svoisky; M. Takahashi; A. Tanasijczuk; W. Taylor; M. Titov; V. V. Tokmenin; D. Tsybychev; B. Tuchming; C. Tully; P. M. Tuts; L. Uvarov

2010-09-29T23:59:59.000Z

87

Search for pair production of the scalar top quark in muon+tau final states  

E-Print Network (OSTI)

We present a search for the pair production of scalar top quarks ($\\tilde{t}_{1}$), 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 $fb^{-1}$} collected with the \\dzero 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{\

D0 Collaboration; V. M. Abazov; B. Abbott; B. S. Acharya; M. Adams; T. Adams; G. D. Alexeev; G. Alkhazov; A. Alton; G. Alverson; M. Aoki; A. Askew; B. Asman; S. Atkins; O. Atramentov; K. Augsten; C. Avila; J. BackusMayes; F. Badaud; L. Bagby; B. Baldin; D. V. Bandurin; S. Banerjee; E. Barberis; P. Baringer; J. Barreto; J. F. Bartlett; U. Bassler; V. Bazterra; A. Bean; M. Begalli; C. Belanger-Champagne; L. Bellantoni; S. B. Beri; G. Bernardi; R. Bernhard; I. Bertram; M. Besancon; R. Beuselinck; V. A. Bezzubov; P. C. Bhat; S. Bhatia; V. Bhatnagar; G. Blazey; S. Blessing; K. Bloom; A. Boehnlein; D. Boline; E. E. Boos; G. Borissov; T. Bose; A. Brandt; O. Brandt; R. Brock; G. Brooijmans; A. Bross; D. Brown; J. Brown; X. B. Bu; M. Buehler; V. Buescher; V. Bunichev; S. Burdin; T. H. Burnett; C. P. Buszello; B. Calpas; E. Camacho-Perez; M. A. Carrasco-Lizarraga; B. C. K. Casey; H. Castilla-Valdez; S. Chakrabarti; D. Chakraborty; K. M. Chan; A. Chandra; E. Chapon; G. Chen; S. Chevalier-Thery; D. K. Cho; S. W. Cho; S. Choi; B. Choudhary; S. Cihangir; D. Claes; J. Clutter; M. Cooke; W. E. Cooper; M. Corcoran; F. Couderc; M. -C. Cousinou; A. Croc; D. Cutts; A. Das; G. Davies; S. J. de Jong; E. De La Cruz-Burelo; F. Deliot; R. Demina; D. Denisov; S. P. Denisov; S. Desai; C. Deterre; K. DeVaughan; H. T. Diehl; M. Diesburg; P. F. Ding; A. Dominguez; T. Dorland; A. Dubey; L. V. Dudko; D. Duggan; A. Duperrin; S. Dutt; A. Dyshkant; M. Eads; D. Edmunds; J. Ellison; V. D. Elvira; Y. Enari; H. Evans; A. Evdokimov; V. N. Evdokimov; G. Facini; T. Ferbel; F. Fiedler; F. Filthaut; W. Fisher; H. E. Fisk; M. Fortner; H. Fox; S. Fuess; A. Garcia-Bellido; G. A. Garcia-Guerra; V. Gavrilov; P. Gay; W. Geng; D. Gerbaudo; C. E. Gerber; Y. Gershtein; G. Ginther; G. Golovanov; A. Goussiou; P. D. Grannis; S. Greder; H. Greenlee; Z. D. Greenwood; E. M. Gregores; G. Grenier; Ph. Gris; J. -F. Grivaz; A. Grohsjean; S. Grunendahl; M. W. Grunewald; T. Guillemin; G. Gutierrez; P. Gutierrez; A. Haas; S. Hagopian; J. Haley; L. Han; K. Harder; A. Harel; J. M. Hauptman; J. Hays; T. Head; T. Hebbeker; D. Hedin; H. Hegab; A. P. Heinson; U. Heintz; C. Hensel; I. Heredia-De La Cruz; K. Herner; G. Hesketh; M. D. Hildreth; R. Hirosky; T. Hoang; J. D. Hobbs; B. Hoeneisen; M. Hohlfeld; Z. Hubacek; V. Hynek; I. Iashvili; Y. Ilchenko; R. Illingworth; A. S. Ito; S. Jabeen; M. Jaffre; D. Jamin; A. Jayasinghe; R. Jesik; K. Johns; M. Johnson; A. Jonckheere; P. Jonsson; J. Joshi; A. W. Jung; A. Juste; K. Kaadze; E. Kajfasz; D. Karmanov; P. A. Kasper; I. Katsanos; R. Kehoe; S. Kermiche; N. Khalatyan; A. Khanov; A. Kharchilava; Y. N. Kharzheev; J. M. Kohli; A. V. Kozelov; J. Kraus; S. Kulikov; A. Kumar; A. Kupco; T. Kurca; V. A. Kuzmin; S. Lammers; G. Landsberg; P. Lebrun; H. S. Lee; S. W. Lee; W. M. Lee; J. Lellouch; H. Li; L. Li; Q. Z. Li; S. M. Lietti; J. K. Lim; D. Lincoln; J. Linnemann; V. V. Lipaev; R. Lipton; Y. Liu; A. Lobodenko; M. Lokajicek; R. Lopes de Sa; H. J. Lubatti; R. Luna-Garcia; A. L. Lyon; A. K. A. Maciel; D. Mackin; R. Madar; R. Magana-Villalba; S. Malik; V. L. Malyshev; Y. Maravin; J. Martinez-Ortega; R. McCarthy; C. L. McGivern; M. M. Meijer; A. Melnitchouk; D. Menezes; P. G. Mercadante; M. Merkin; A. Meyer; J. Meyer; F. Miconi; N. K. Mondal; G. S. Muanza; M. Mulhearn; E. Nagy; M. Naimuddin; M. Narain; R. Nayyar; H. A. Neal; J. P. Negret; P. Neustroev; S. F. Novaes; T. Nunnemann; G. Obrant; J. Orduna; N. Osman; J. Osta; G. J. Otero y Garzon; M. Padilla; A. Pal; N. Parashar; V. Parihar; S. K. Park; R. Partridge; N. Parua; A. Patwa; B. Penning; M. Perfilov; Y. Peters; K. Petridis; G. Petrillo; P. Petroff; R. Piegaia; M. -A. Pleier; P. L. M. Podesta-Lerma; V. M. Podstavkov; P. Polozov; A. V. Popov; M. Prewitt; D. Price; N. Prokopenko; J. Qian; A. Quadt; B. Quinn; M. S. Rangel; K. Ranjan; P. N. Ratoff; I. Razumov; P. Renkel; M. Rijssenbeek; I. Ripp-Baudot; F. Rizatdinova; M. Rominsky; A. Ross; C. Royon; P. Rubinov; R. Ruchti; G. Safronov; G. Sajot; P. Salcido; A. Sanchez-Hernandez; M. P. Sanders; B. Sanghi; A. S. Santos; G. Savage; L. Sawyer; T. Scanlon; R. D. Schamberger; Y. Scheglov; H. Schellman; T. Schliephake; S. Schlobohm; C. Schwanenberger; R. Schwienhorst; J. Sekaric; H. Severini; E. Shabalina; V. Shary; A. A. Shchukin; R. K. Shivpuri; V. Simak; V. Sirotenko; P. Skubic; P. Slattery; D. Smirnov; K. J. Smith; G. R. Snow; J. Snow; S. Snyder; S. Soldner-Rembold; L. Sonnenschein; K. Soustruznik; J. Stark; V. Stolin; D. A. Stoyanova; M. Strauss; D. Strom; L. Stutte; L. Suter; P. Svoisky; M. Takahashi; A. Tanasijczuk; M. Titov; V. V. Tokmenin; Y. -T. Tsai; K. Tschann-Grimm; D. Tsybychev; B. Tuchming; C. Tully; L. Uvarov; S. Uvarov; S. Uzunyan; R. Van Kooten; W. M. van Leeuwen; N. Varelas; E. W. Varnes; I. A. Vasilyev; P. Verdier; L. S. Vertogradov; M. Verzocchi; M. Vesterinen; D. Vilanova; P. Vokac

2012-02-09T23:59:59.000Z

88

The Top Quark, Its Discovery, and Subsequent Research  

Office of Scientific and Technical Information (OSTI)

The Top Quark, Its Discovery, and Subsequent Research 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 observed in two experiments at the Tevatron proton-antiproton collider at Fermilab. ... Top Quark Courtesy Fermilab Top is the last of the fundamental constituents of subnuclear matter that theories of the strong, weak, and electromagnetic interactions and a wealth of experimental information had led particle physicists to expect. Theoretically, top's existence was required to make the electroweak theory internally consistent.'1

89

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

NLE Websites -- All DOE Office Websites (Extended Search)

top quark mass are discussed in detail. The associated production of a tE pair and a Higgs boson in either e+e- or hadronic collisions is presented at next-to-leading-order QCD and...

90

Proceedings of the 1992 workshops on high-energy physics with colliding beams. Volume 2, Studies of top quarks at colliding-beam facilities  

Science Conference Proceedings (OSTI)

This report contains brief papers and viewgraphs on studies of top quarks. Topics on productions, decay, mass, symmetry violation all related to top quarks are discussed in these papers.

Rogers, J. [ed.

1992-12-31T23:59:59.000Z

91

Top Quark Production and Properties at the Tevatron  

E-Print Network (OSTI)

The precise measurement of top quark production and properties is one of the primary goals of the Tevatron during Run II. The total top-antitop 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 top-antitop 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 of data, are presented.

Frank Fiedler; for the D0; CDF Collaborations

2005-06-02T23:59:59.000Z

92

Top quark and charged Higgs production at hadron colliders  

Science Conference Proceedings (OSTI)

I present a brief theoretical update on top quark pair production at the Tevatron and give values of the NNLO-NNNLL cross section for both mt = 175 and 178 GeV. I then present a calculation of the cross section for charged Higgs production in association with a top quark at the LHC, including NNLO soft-gluon corrections.

Kidonakis, Nikolaos [Kennesaw State University, Physics no. 1202, 1000 Chastain Rd, Kennesaw, GA 30144-5591 (United States)

2005-10-06T23:59:59.000Z

93

Charged Higgs production with a top quark at the LHC.  

E-Print Network (OSTI)

ar X iv :h ep -p h/ 04 06 17 9v 1 1 6 Ju n 20 04 Cavendish-HEP-04/17 Charged Higgs production with a top quark at the LHC1 Nikolaos Kidonakis Cavendish Laboratory, University of Cambridge Madingley Road, Cambridge CB3 0HE, UK E-mail: kidonaki... @hep.phy.cam.ac.uk Abstract I discuss charged Higgs production via the process bg ? tH? at the LHC. I show that the cross section is dominated by soft-gluon corrections and I provide results for its dependence on the charged Higgs mass and on the scale, including higher...

Kidonakis, Nikolaos

94

A Direct Measurement of the Total Decay Width of the Top Quark  

E-Print Network (OSTI)

We present a measurement of the total decay width of the top quark using events with top-antitop-quark pair candidates reconstructed in the final state with one charged lepton and four or more hadronic jets. We use the full Tevatron Run II data set of $\\sqrt{s} = 1.96$ TeV proton-antiproton collisions recorded by the CDF II detector. The top-quark mass and the mass of the hadronically-decaying $W$ boson are reconstructed for each event and compared with distributions derived from simulated signal and background samples to extract the top-quark width (\\gmt) and the energy scale of the calorimeter jets with {\\it in-situ} calibration. For a top-quark mass $\\mtop = \\gevcc{172.5}$, we find $1.10<\\gmt<\\gev{4.05}$ at 68% confidence level, which is in agreement with the standard-model expectation of \\gev{1.3} and is the most precise direct measurement of the top-quark width to date.

CDF Collaboration; T. Aaltonen; S. Amerio; D. Amidei; A. Anastassov; A. Annovi; J. Antos; G. Apollinari; J. A. Appel; T. Arisawa; A. Artikov; J. Asaadi; W. Ashmanskas; B. Auerbach; A. Aurisano; F. Azfar; W. Badgett; T. Bae; A. Barbaro-Galtieri; V. E. Barnes; B. A. Barnett; P. Barria; P. Bartos; M. Bauce; F. Bedeschi; S. Behari; G. Bellettini; J. Bellinger; D. Benjamin; A. Beretvas; A. Bhatti; K. R. Bland; B. Blumenfeld; A. Bocci; A. Bodek; D. Bortoletto; J. Boudreau; A. Boveia; L. Brigliadori; C. Bromberg; E. Brucken; J. Budagov; H. S. Budd; K. Burkett; G. Busetto; P. Bussey; P. Butti; A. Buzatu; A. Calamba; S. Camarda; M. Campanelli; F. Canelli; B. Carls; D. Carlsmith; R. Carosi; S. Carrillo; B. Casal; M. Casarsa; A. Castro; P. Catastini; D. Cauz; V. Cavaliere; M. Cavalli-Sforza; A. Cerri; L. Cerrito; Y. C. Chen; M. Chertok; G. Chiarelli; G. Chlachidze; K. Cho; D. Chokheli; A. Clark; C. Clarke; M. E. Convery; J. Conway; M. Corbo; M. Cordelli; C. A. Cox; D. J. Cox; M. Cremonesi; D. Cruz; J. Cuevas; R. Culbertson; N. d'Ascenzo; M. Datta; P. de Barbaro; L. Demortier; L. Marchese; M. Deninno; F. Devoto; M. D'Errico; A. Di Canto; B. Di Ruzza; J. R. Dittmann; M. D'Onofrio; S. Donati; M. Dorigo; A. Driutti; K. Ebina; R. Edgar; A. Elagin; R. Erbacher; S. Errede; B. Esham; S. Farrington; J. P. Fernández Ramos; R. Field; G. Flanagan; R. Forrest; M. Franklin; J. C. Freeman; H. Frisch; Y. Funakoshi; C. Galloni; A. F. Garfinkel; P. Garosi; H. Gerberich; E. Gerchtein; S. Giagu; V. Giakoumopoulou; K. Gibson; C. M. Ginsburg; N. Giokaris; P. Giromini; G. Giurgiu; V. Glagolev; D. Glenzinski; M. Gold; D. Goldin; A. Golossanov; G. Gomez; G. Gomez-Ceballos; M. Goncharov; O. González López; I. Gorelov; A. T. Goshaw; K. Goulianos; E. Gramellini; S. Grinstein; C. Grosso-Pilcher; R. C. Group; J. Guimaraes da Costa; S. R. Hahn; J. Y. Han; F. Happacher; K. Hara; M. Hare; R. F. Harr; T. Harrington-Taber; K. Hatakeyama; C. Hays; J. Heinrich; M. Herndon; A. Hocker; Z. Hong; W. Hopkins; S. Hou; R. E. Hughes; U. Husemann; M. Hussein; J. Huston; G. Introzzi; M. Iori; A. Ivanov; E. James; D. Jang; B. Jayatilaka; E. J. Jeon; S. Jindariani; M. Jones; K. K. Joo; S. Y. Jun; T. R. Junk; M. Kambeitz; T. Kamon; P. E. Karchin; A. Kasmi; Y. Kato; W. Ketchum; J. Keung; B. Kilminster; D. H. Kim; H. S. Kim; J. E. Kim; M. J. Kim; S. B. Kim; S. H. Kim; Y. K. Kim; Y. J. Kim; N. Kimura; M. Kirby; K. Knoepfel; K. Kondo; D. J. Kong; J. Konigsberg; A. V. Kotwal; M. Kreps; J. Kroll; M. Kruse; T. Kuhr; M. Kurata; A. T. Laasanen; S. Lammel; M. Lancaster; K. Lannon; G. Latino; H. S. Lee; J. S. Lee; S. Leo; S. Leone; J. D. Lewis; A. Limosani; E. Lipeles; A. Lister; H. Liu; Q. Liu; T. Liu; S. Lockwitz; A. Loginov; A. Lucà; D. Lucchesi; J. Lueck; P. Lujan; P. Lukens; G. Lungu; J. Lys; R. Lysak; R. Madrak; P. Maestro; S. Malik; G. Manca; A. Manousakis-Katsikakis; F. Margaroli; P. Marino; M. Martínez; K. Matera; M. E. Mattson; A. Mazzacane; P. Mazzanti; R. McNulty; A. Mehta; P. Mehtala; C. Mesropian; T. Miao; D. Mietlicki; A. Mitra; H. Miyake; S. Moed; N. Moggi; C. S. Moon; R. Moore; M. J. Morello; A. Mukherjee; Th. Muller; P. Murat; M. Mussini; J. Nachtman; Y. Nagai; J. Naganoma; I. Nakano; A. Napier; J. Nett; C. Neu; T. Nigmanov; L. Nodulman; S. Y. Noh; O. Norniella; L. Oakes; S. H. Oh; Y. D. Oh; I. Oksuzian; T. Okusawa; R. Orava; L. Ortolan; C. Pagliarone; E. Palencia; P. Palni; V. Papadimitriou; W. Parker; G. Pauletta; M. Paulini; C. Paus; T. J. Phillips; G. Piacentino; E. Pianori; J. Pilot; K. Pitts; C. Plager; L. Pondrom; S. Poprocki; K. Potamianos; F. Prokoshin; A. Pranko; F. Ptohos; G. Punzi; N. Ranjan; I. Redondo Fernández; P. Renton; M. Rescigno; F. Rimondi; L. Ristori; A. Robson; T. Rodriguez; S. Rolli; M. Ronzani; R. Roser; J. L. Rosner; F. Ruffini; A. Ruiz; J. Russ; V. Rusu; W. K. Sakumoto; Y. Sakurai; L. Santi; K. Sato; V. Saveliev; A. Savoy-Navarro; P. Schlabach; E. E. Schmidt; T. Schwarz; L. Scodellaro; F. Scuri; S. Seidel; Y. Seiya; A. Semenov; F. Sforza; S. Z. Shalhout; T. Shears; P. F. Shepard; M. Shimojima; M. Shochet; I. Shreyber-Tecker; A. Simonenko; K. Sliwa; J. R. Smith; F. D. Snider; V. Sorin; H. Song; M. Stancari; R. St. Denis; D. Stentz; J. Strologas; Y. Sudo; A. Sukhanov; I. Suslov; K. Takemasa; Y. Takeuchi; J. Tang; M. Tecchio; P. K. Teng; J. Thom; E. Thomson; V. Thukral; D. Toback; S. Tokar; K. Tollefson; T. Tomura; D. Tonelli; S. Torre; D. Torretta; P. Totaro; M. Trovato; F. Ukegawa; S. Uozumi; F. Vázquez; G. Velev; C. Vellidis; C. Vernieri; M. Vidal; R. Vilar; J. Vizán; M. Vogel; G. Volpi; P. Wagner; R. Wallny; S. M. Wang; D. Waters; W. C. Wester III; D. Whiteson; A. B. Wicklund; S. Wilbur; H. H. Williams; J. S. Wilson; P. Wilson; B. L. Winer; P. Wittich; S. Wolbers; H. Wolfe; T. Wright; X. Wu; Z. Wu; K. Yamamoto; D. Yamato; T. Yang; U. K. Yang; Y. C. Yang; W. -M. Yao; G. P. Yeh; K. Yi; J. Yoh; K. Yorita; T. Yoshida; G. B. Yu

2013-08-19T23:59:59.000Z

95

Next-to-next-to-leading-order collinear and soft gluon corrections for t-channel single top quark production  

SciTech Connect

I present the resummation of collinear and soft-gluon corrections to single top quark production in the t channel at next-to-next-to-leading logarithm accuracy using two-loop soft anomalous dimensions. The expansion of the resummed cross section yields approximate next-to-next-to-leading-order cross sections. Numerical results for t-channel single top quark (or single antitop) production at the Tevatron and the LHC are presented, including the dependence of the cross sections on the top quark mass and the uncertainties from scale variation and parton distributions. Combined results for all single top quark production channels are also given.

Kidonakis, Nikolaos [Kennesaw State University, Physics 1202, 1000 Chastain Road, Kennesaw, Georgia 30144-5591 (United States)

2011-05-01T23:59:59.000Z

96

Quark masses : an environmental impact statement  

E-Print Network (OSTI)

We investigate how the requirement that organic chemistry be possible constrains the values of the quark masses. Specifically, we choose a slice through the parameter space of the Standard Model in which quark masses vary ...

Kimchi, Itamar

2008-01-01T23:59:59.000Z

97

Top Turns Ten: Celebrating the Discovery of the Top Quark (Video presentations from Fermilab)  

DOE Data Explorer (OSTI)

The scientific lectures marking the tenth anniversary of the discovery of the Top Quark were given at Fermilab on October 21, 2005. The available videos include: 1) Opening Remarks by Pier Oddone and an Introduction by Alvin Tolestrup; 2) Paving the Road to Top; 3) Pbars and the Road to the Top; 4) Why the Top; 5) Top Importance; 6) CDF Detector and Silicon Vertex Detector (SVX); 7) CDF’s Road to Top; 8) Perspectives of the (then) Young Physicists; 9) The DZero Graduate Student Perspective; 10) A Perspective from the Trenches at DZero (1992 - 1995); 11) DZero Top III (Double Secret Probation); 12) Topping the Top.

98

Exposing the dressed quark's mass  

E-Print Network (OSTI)

This snapshot of recent progress in hadron physics made in connection with QCD's Dyson-Schwinger equations includes: a perspective on confinement and dynamical chiral symmetry breaking (DCSB); a pre'cis on the physics of in-hadron condensates; results on the hadron spectrum, including dressed-quark-core masses for the nucleon and Delta, their first radial excitations, and the parity-partners of these states; an illustration of the impact of DCSB on the electromagnetic pion form factor, thereby exemplifying how data can be used to chart the momentum-dependence of the dressed-quark mass function; and a prediction that F_1^{p,d}/F_1^{p,u} passes through zero at Q^2\\approx 5m_N^2 owing to the presence of nonpointlike scalar and axial-vector diquark correlations in the nucleon.

Roberts, H L L; Cloet, I C; Roberts, C D

2010-01-01T23:59:59.000Z

99

Angular correlations in top quark decays in standard model extensions  

SciTech Connect

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.

Batebi, S. [Science and Research Branch, Islamic Azad University (IAU), Tehran (Iran, Islamic Republic of); Etesami, S. M. [School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Physics Department, Isfahan University of Technology (IUT), P.O. Box 11365-9161, Isfahan (Iran, Islamic Republic of); Mohammadi-Najafabadi, M. [Physics Department, Isfahan University of Technology (IUT), P.O. Box 11365-9161, Isfahan (Iran, Islamic Republic of)

2011-03-01T23:59:59.000Z

100

Top quark spin correlations and polarization at the LHC: standard model predictions and effects of anomalous top chromo moments  

E-Print Network (OSTI)

A number of top-spin observables are computed within the Standard Model (SM), at next-to-leading order in the strong and weak gauge couplings for hadronic top-quark anti-quark (ttbar) production and decay at the LHC for center-of-mass energies 7 and 8 TeV. For dileptonic final states we consider the azimuthal angle correlation, the helicity correlation, and the opening angle distribution; for lepton plus jets final states we determine distributions and asymmetries that trace a longitudinal and transverse polarization, respectively, of the t and t-bar samples. The QCD-induced transverse polarization of the top quarks leads to an asymmetry of about 8 percent that should be detectable with existing data. In addition, we investigate the effects of a non-zero chromo-magnetic and chromo-electric dipole moment of the top quark on these and other top-spin observables and associated asymmetries. These observables allow to disentangle the contributions from the real and imaginary parts of these moments.

Werner Bernreuther; Zong-Guo Si

2013-05-09T23:59:59.000Z

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101

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

SciTech Connect

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.

Naganoma, Junji; /Waseda U.

2008-03-01T23:59:59.000Z

102

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

SciTech Connect

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.

Naganoma, Junji; /Waseda U.

2008-03-01T23:59:59.000Z

103

Next-to-next-to-leading logarithm resummation for s-channel single top quark production  

Science Conference Proceedings (OSTI)

I present the next-to-next-to-leading-logarithm (NNLL) resummation of soft and collinear gluon corrections to single top quark production in the s channel. Attaining NNLL accuracy involves the calculation of the two-loop soft anomalous dimension for the partonic subprocesses. Finite-order expansions of the resummed cross section are calculated through next-to-next-to-leading order. Numerical results are presented for s-channel single top quark production at the Tevatron and the LHC, including the dependence of the cross sections on the top quark mass and the uncertainties in the theoretical prediction. The higher-order corrections are significant for energies at both colliders and they decrease the theoretical uncertainty.

Kidonakis, Nikolaos [Kennesaw State University, Physics 1202, 1000 Chastain Road, Kennesaw, 30144-5591 (Georgia)

2010-03-01T23:59:59.000Z

104

Top quarks at the Tevatron: Measurements of the top quark production and decay with the D0 experiment  

Science Conference Proceedings (OSTI)

This thesis presents two measurements of the to pquark using 230 pb{sup -1} of data recorded with the D0 detector at the Tevatron accelerator. The first measurement determines the top pair production cross section at {radical}s = 1.96 TeV in proton-antiproton collisions. In the standard model of particle physics the top quark decays almost exclusively into a W boson and a b quark. Candidate events are selected by requiring that at least one jet in the event is tagged with the secondary vertex algorithm.

Strandberg, Jonas; /Stockholm U.

2006-04-01T23:59:59.000Z

105

Charged-Higgs-boson search via heavy-top-quark decay at Fermilab Tevatron collider energy  

SciTech Connect

Assuming a top-quark mass of about 150 GeV we analyze the prospects for a charged-Higgs-boson search in top-quark decay at the Fermilab Tevatron upgrade. Universality predicts the relative size of the top decay signal via {ital W} boson in different decay channels, and an observable excess over this prediction can be used as a signature for charged-Higgs-boson production. In the charged-Higgs-boson--fermion coupling scheme suggested by minimal supersymmetry and E{sub 6} string-inspired models one expects to see an observable signal up to a charged-Higgs-boson mass of 100 GeV throughout the allowed range of the coupling parameter tan{beta}. The absence of such a signal would give an unambiguous charged-Higgs-boson mass limit of 100 GeV. This is not possible however in the alternative coupling schemes of two-Higgs-doublet models.

Godbole, R.M. (Department of Physics, University of Bombay, Bombay 400098 (India)); Roy, D.P. (Tata Institute of Fundamental Research, Homi Bhabha Road, Bombay 400005 (India))

1991-06-01T23:59:59.000Z

106

Observation of Electroweak Single Top-Quark Production with the CDF II Experiment  

SciTech Connect

The standard model of elementary particle physics (SM) predicts, besides the top-quark pair production via the strong interaction, also the electroweak production of single top-quarks [19]. Up to now, the Fermilab Tevatron proton-antiproton-collider is the only place to produce and study top quarks emerging from hadron-hadron-collisions. Top quarks were directly observed in 1995 during the Tevatron Run I at a center-of-mass energy of {radical}s = 1.8 TeV simultaneously by the CDF and D0 Collaborations via the strong production of top-quark pairs. Run II of the Tevatron data taking period started 2001 at {radical}s = 1.96 TeV after a five year upgrade of the Tevatron accelerator complex and of both experiments. One main component of its physics program is the determination of the properties of the top quark including its electroweak production. Even though Run II is still ongoing, the study of the top quark is already a successful endeavor, confirmed by dozens of publications from both Tevatron experiments. A comprehensive review of top-quark physics can be found in reference. The reasons for searching for single top-quark production are compelling. As the electroweak top-quark production proceeds via a Wtb vertex, it provides the unique opportunity of the direct measurement of the CKM matrix element |V{sub tb}|, which is expected to be |V{sub tb}| {approx} 1 in the SM. Significant deviations from unity could be an indication of a fourth quark generation, a production mode via flavor-changing neutral currents, and other new phenomena, respectively. There are two dominating electroweak top-quark production modes at the Fermilab Tevatron: the t-channel exchange of a virtual W boson striking a b quark and the s-channel production of a timelike W boson via the fusion of two quarks. In proton-antiproton-collisions the third electroweak production mode, the associated Wt production of an on-shell W boson in conjunction with a top quark has a comparatively negligible small predicted cross section. Therefore, the vast majority of the CDF and D0 single top-quark analyses search for the combined s- and t-channel signal, with the production ratio to be given by the SM. In Tevatron Run I, several limits on the single top-quark production cross section were set by CDF and D0, whereas in Run II, even stronger limits followed by both collaborations. Furthermore, limits on the non-SM production of single top-quarks via flavor-changing neutral currents could be obtained. The electroweak production of single top-quarks has not yet been observed up to the time of this thesis, although the D0 and shortly thereafter the CDF Collaborations found first evidence. The experimental challenge of the search for single top-quark production is the tiny expected signal beneath a large and imprecisely known amount of background processes. The relative fraction of background events is at the order of about ten times higher compared to the top-quark pair production. Consequently, the expected signal amounts to about 5% of the full candidate event sample whose background contribution is only known to a level at the order of 20%. Furthermore, the signal events themselves are expected to be not as distinct from the background as the top-quark pair production since there is only one heavy object present in the event. Thus, experimental methods like simple counting experiments are not sufficiently sensitive and the development of more sophisticated analysis techniques is required to distinguish such small signals from alike and inaccurately known background processes. Neural networks comply with those requirements. They can be used to distinguish between signal and background processes by combining the information contained in several variables into a powerful discriminant, while each variable has a rather low separation capability. The application of those neural network discriminants to collision data provide a method for the extraction of the signal fraction and its significance. This thesis presents a neural network search for combined as well as separate

Lueck, Jan; /KARLSRUHE U., EKP

2009-07-01T23:59:59.000Z

107

Observation of Electroweak Single Top-Quark Production with the CDF II Experiment  

Science Conference Proceedings (OSTI)

The standard model of elementary particle physics (SM) predicts, besides the top-quark pair production via the strong interaction, also the electroweak production of single top-quarks [19]. Up to now, the Fermilab Tevatron proton-antiproton-collider is the only place to produce and study top quarks emerging from hadron-hadron-collisions. Top quarks were directly observed in 1995 during the Tevatron Run I at a center-of-mass energy of {radical}s = 1.8 TeV simultaneously by the CDF and D0 Collaborations via the strong production of top-quark pairs. Run II of the Tevatron data taking period started 2001 at {radical}s = 1.96 TeV after a five year upgrade of the Tevatron accelerator complex and of both experiments. One main component of its physics program is the determination of the properties of the top quark including its electroweak production. Even though Run II is still ongoing, the study of the top quark is already a successful endeavor, confirmed by dozens of publications from both Tevatron experiments. A comprehensive review of top-quark physics can be found in reference. The reasons for searching for single top-quark production are compelling. As the electroweak top-quark production proceeds via a Wtb vertex, it provides the unique opportunity of the direct measurement of the CKM matrix element |V{sub tb}|, which is expected to be |V{sub tb}| {approx} 1 in the SM. Significant deviations from unity could be an indication of a fourth quark generation, a production mode via flavor-changing neutral currents, and other new phenomena, respectively. There are two dominating electroweak top-quark production modes at the Fermilab Tevatron: the t-channel exchange of a virtual W boson striking a b quark and the s-channel production of a timelike W boson via the fusion of two quarks. In proton-antiproton-collisions the third electroweak production mode, the associated Wt production of an on-shell W boson in conjunction with a top quark has a comparatively negligible small predicted cross section. Therefore, the vast majority of the CDF and D0 single top-quark analyses search for the combined s- and t-channel signal, with the production ratio to be given by the SM. In Tevatron Run I, several limits on the single top-quark production cross section were set by CDF and D0, whereas in Run II, even stronger limits followed by both collaborations. Furthermore, limits on the non-SM production of single top-quarks via flavor-changing neutral currents could be obtained. The electroweak production of single top-quarks has not yet been observed up to the time of this thesis, although the D0 and shortly thereafter the CDF Collaborations found first evidence. The experimental challenge of the search for single top-quark production is the tiny expected signal beneath a large and imprecisely known amount of background processes. The relative fraction of background events is at the order of about ten times higher compared to the top-quark pair production. Consequently, the expected signal amounts to about 5% of the full candidate event sample whose background contribution is only known to a level at the order of 20%. Furthermore, the signal events themselves are expected to be not as distinct from the background as the top-quark pair production since there is only one heavy object present in the event. Thus, experimental methods like simple counting experiments are not sufficiently sensitive and the development of more sophisticated analysis techniques is required to distinguish such small signals from alike and inaccurately known background processes. Neural networks comply with those requirements. They can be used to distinguish between signal and background processes by combining the information contained in several variables into a powerful discriminant, while each variable has a rather low separation capability. The application of those neural network discriminants to collision data provide a method for the extraction of the signal fraction and its significance. This thesis presents a neural network search for combined as well as separate

Lueck, Jan; /KARLSRUHE U., EKP

2009-07-01T23:59:59.000Z

108

Investigation of top mass measurements with the ATLAS detector at LHC  

E-Print Network (OSTI)

Several methods for the determination of the mass of the top quark with the ATLAS detector at the LHC are presented. All dominant decay channels of the top quark can be explored. The measurements are in most cases dominated by systematic uncertainties. New methods have been developed to control those related to the detector. The results indicate that a total error on the top mass at the level of 1 GeV should be achievable.

I. Borjanovic; I. Efthymiopoulos; F. Fassi; P. Grenier; P. Homola; V. Kostioukhine; R. Leitner; I. Mendas; D. Pallin; D. Popovic; P. Roy; V. Simak; L. Simic; G. Skoro; J. Valenta

2004-03-15T23:59:59.000Z

109

Determining Top Quark Couplings at the LHC: Snowmass White Paper  

E-Print Network (OSTI)

Top quarks are a prime system for hunting for new physics. Nonetheless, two decades on from their discovery few of their couplings have been measured to high precision. We present an overview of current determinations and the expected sensitivities with 300 fb-1 and 3000 fb-1 of 14 TeV LHC data. In addition to direct limits on the top quark's renormalizable couplings to Standard Model bosons, we also explore what bounds can be set on the coefficients of higher-dimension operators, taking particular four-fermion operators that do not interfere with QCD as a test case. Every coupling we consider will benefit greatly from a dedicated study at the future LHC. Some measurements, like the irrelevant operators, are systematics-limited and will saturate in the near-term. Others, like the important ttbar+Higgs coupling, involve rare processes and thus demand as much data as possible.

Jahred Adelman; Matthew Baumgart; Aran Garcia-Bellido; Andrey Loginov

2013-08-24T23:59:59.000Z

110

Forward-backward asymmetry in top quark-antiquark production  

SciTech Connect

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.

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.

2011-12-12T23:59:59.000Z

111

Single top quark production at the Fermilab Tevatron: Threshold resummation and finite-order soft gluon corrections  

SciTech Connect

I present a calculation of threshold soft-gluon corrections to single top-quark production in pp collisions via all partonic processes in the t and s channels and via associated top quark and W boson production. The soft-gluon corrections are formally resummed to all orders, and finite-order expansions of the resummed cross section are calculated through next-to-next-to-next-to-leading-order (NNNLO) at next-to-leading logarithmic (NLL) accuracy. Numerical results for single top-quark production at the Tevatron are presented, including the dependence of the cross sections on the top-quark mass and on the factorization and renormalization scales. The threshold corrections in the t channel are small while in the s channel they are large and dominant. Associated tW production remains relatively minor due to the small leading-order cross section even though the K factors are large.

Kidonakis, Nikolaos [Kennesaw State University, Physics 1202, 1000 Chastain Rd., Kennesaw, Georgia 30144-5591 (United States)

2006-12-01T23:59:59.000Z

112

Single top quark production cross section at the Tevatron  

E-Print Network (OSTI)

The latest results on the measurements of electroweak top-quark production at the Tevatron are presented with the full RunII dataset. The CDF and D0 Collaborations have performed measurements of the s, t, and s+t channels in both l+jets and MET+jets final states. Evidence for the production of the s channel is presented for the first time.

Aran Garcia-Bellido; for the CDF; D0 Collaborations

2013-10-12T23:59:59.000Z

113

Top quark pair production cross section at the Tevatron  

SciTech Connect

Top quark pair production cross section has been measured at the Tevatron by CDF and D0 collaborations using different channels and methods, in order to test standard model predictions, and to search for new physics hints affecting the t{bar t} production mechanism or decay. Measurements are carried out with an integrated luminosity of 1.0 to 2.0 fb{sup -1}, and are found to be consistent with standard model expectations.

Cortiana, Giorgio; /INFN, Padua /Padua U.

2008-04-01T23:59:59.000Z

114

Study of the top quark electric charge at the CDF experiment  

Science Conference Proceedings (OSTI)

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.

Bartos, Pavol; /Comenius U.

2011-09-01T23:59:59.000Z

115

Constraints on the gluon PDF from top quark pair production at hadron colliders  

E-Print Network (OSTI)

Using the recently derived NNLO cross sections \\cite{Czakon:2013goa}, we provide NNLO+NNLL theoretical predictions for top quark pair production based on all the available NNLO PDF sets, and compare them with the most precise LHC and Tevatron data. In this comparison we study in detail the PDF uncertainty and the scale, $m_t$ and $\\alpha_s$ dependence of the theoretical predictions for each PDF set. Next, we observe that top quark pair production provides a powerful direct constraint on the gluon PDF at large $x$, and include Tevatron and LHC top pair data consistently into a global NNLO PDF fit. We then explore the phenomenological consequences of the reduced gluon PDF uncertainties, by showing how they can improve predictions for Beyond the Standard Model processes at the LHC. Finally, we update to full NNLO+NNLL the theoretical predictions for the ratio of top quark cross sections between different LHC center of mass energies, as well as the cross sections for hypothetical heavy fourth-generation quark production at the LHC.

Michal Czakon; Michelangelo L. Mangano; Alexander Mitov; Juan Rojo

2013-03-28T23:59:59.000Z

116

Measurement of W-Boson Polarization in Top-Quark Decay in pp[over-bar] Collisions at [sqrt]s=1.96 TeV  

E-Print Network (OSTI)

We report measurements of the polarization of W bosons from top-quark decays using 2.7 fb[superscript -1] of pp[over-bar] collisions collected by the CDF II detector. Assuming a top-quark mass of 175??GeV/c[superscript 2], ...

Bauer, Gerry P.

117

Triangular mass matrices for quarks and leptons  

E-Print Network (OSTI)

We assume that all quark and lepton $3 \\times 3$ mass matrices which appear in the standard model lagrangian (after spontaneous symmetry breaking) with neutrinos treated as Dirac patricles have the triangular form. Such matrices have not only less non-zero elements (three of them are equal to zero) but also lead to very asymmetrical decomposition into one diagonal and two unitary matrices for quarks and leptons. We also assume that unitary matrices which transform flavor into definite mass states for right handed components (weakly non-interacting) in the same weak isodoublet are equal. Using all available experimental data on quark and lepton masses and mixing angles, treating in the universal way quarks and leptons, we determine the triangular mass matrices for up and down type quarks, neutrinos and charged leptons and as a consequence mixing matrices for left-handed and right handed components. As the result of the fit we get predictions for the neutrino masses including smallest neutrino mass. The calculations without CP violation and with inclusion of this effect in quark sector are also presented.

S. Tatur; J. Bartelski

2006-05-24T23:59:59.000Z

118

Quark masses from lattice QCD and the study of textures  

E-Print Network (OSTI)

I review how the determination of quark masses from lattice QCD can be used to study textures in quark mass matrices. This type of theory relates quark masses to CKM matrix elements. I demonstrate how the recent precision results from the HPQCD and MILC collaborations for quark masses can be used to test some of these ideas.

Craig McNeile

2010-04-28T23:59:59.000Z

119

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

SciTech Connect

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.

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.

2012-04-20T23:59:59.000Z

120

Evidence for single top quark production using Bayesian neural networks  

SciTech Connect

We present results of a search for single top quark production in p{bar p} collisions using a dataset of approximately 1 fb{sup -1} collected with the D0 detector. This analysis considers the muon+jets and electron+jets final states and makes use of Bayesian neural networks to separate the expected signals from backgrounds. The observed excess is associated with a p-value of 0.081%, assuming the background-only hypothesis, which corresponds to an excess over background of 3.2 standard deviations for a Gaussian density. The p-value computed using the SM signal cross section of 2.9 pb is 1.6%, corresponding to an expected significance of 2.2 standard deviations. Assuming the observed excess is due to single top production, we measure a single top quark production cross section of {sigma}(p{bar p} {yields} tb + X, tqb + X) = 4.4 {+-} 1.5 pb.

Kau, Daekwang; /Florida State U.

2007-08-01T23:59:59.000Z

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121

Top quark production at the Tevatron at NNLO.  

E-Print Network (OSTI)

of Nuclear Physics of the Office of High Energy and Nuclear Physics of the U.S. Department of Energy under Contract No. DE-AC-03-76SF00098. References [1] N. Kidonakis and R. Vogt, hep-ph/0308222. [2] N. Kidonakis, hep-ph/0303186. [3] N. Kidonakis and G... , UK bNuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA and Physics Department, University of California at Davis, Davis, CA 95616, USA Abstract We present results for top quark production at the Tevatron including...

Kidonakis, Nikolaos; Vogt, Ramona

122

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

DOE Data Explorer (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.

123

Search for Charged Higgs Boson Decays of the Top Quark Using Hadronic tau Decays  

SciTech Connect

We present the result of a search for charged Higgs boson decays of the top quark, produced in p{bar p} collisions at {radical}s = 1.8 TeV. When the charged Higgs boson is heavy and decays to a {tau} lepton, which subsequently decays hadronically, the resulting events have a unique signature: large missing transverse energy and the low-charged-multiplicity {tau}. Data collected in 1992 and 1993 at the Collider Detector at Fermilab, corresponding to 18.7 {+-} 0.7 pb{sup -1}, exclude new regions of combined top quark and charged Higgs boson mass, in extensions to the standard model with two Higgs doublets.

Abe, F.

1996-01-01T23:59:59.000Z

124

Top Quark Anomalous Couplings at the International Linear Collider  

SciTech Connect

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 quark to the photon, the Z and the W bosons at a level of precision that is difficult to achieve at hadron colliders. Measurement of the forward-backward asymmetry requires excellent b quark identification and determination of the quark charge. The study reported here is performed in the most challenging all-hadronic channel e{sup +}e{sup -} {yields} b{bar b}q{bar q}q{bar q}. It includes realistic details of the experimental environment, a full Monte Carlo simulation of the detector, based on the Silicon Detector concept, and realistic event reconstruction. The forward-backward asymmetries are determined to a precision of approximately 1% for each of two choices of beam polarization. We analyze the implications for the determination of the t{bar t}Z and Wt{bar b} couplings.

Devetak, Erik; Nomerotski, Andrei; /Oxford U.; Peskin, Michael; /SLAC

2011-08-15T23:59:59.000Z

125

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

SciTech Connect

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.

Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U. /Fermilab; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Arisawa, T.; /Waseda U.; Artikov, A.; /Dubna, JINR /Texas A-M

2012-03-01T23:59:59.000Z

126

Improved Wilson QCD simulations with light quark masses  

E-Print Network (OSTI)

We present results from simulations using 2 flavours of O(a)-improved Wilson quarks whose masses are about 1/3 of the physical strange quark mass. We present new data on the mass of the singlet pseudoscalar meson and evidence of the onset of chiral logarithms in the pion decay constant. The previously observed suppression of the topological susceptibility at lighter quark masses is confirmed. We report on the performance of the hybrid Monte Carlo algorithm at light quark masses.

CR Allton; A Hart; D Hepburn; AC Irving; B Joo; C McNeile; C Michael; SV Wright

2004-03-04T23:59:59.000Z

127

Quark mass thresholds in QCD thermodynamics  

E-Print Network (OSTI)

We discuss radiative corrections to how quark mass thresholds are crossed, as a function of the temperature, in basic thermodynamic observables such as the pressure, the energy and entropy densities, and the heat capacity of high temperature QCD. The indication from leading order that the charm quark plays a visible role at surprisingly low temperatures, is confirmed. We also sketch a way to obtain phenomenological estimates relevant for generic expansion rate computations at temperatures between the QCD and electroweak scales, pointing out where improvements over the current knowledge are particularly welcome.

M. Laine; Y. Schroder

2006-03-06T23:59:59.000Z

128

Searches for flavor-changing neutral currents and single top quarks at D0  

SciTech Connect

I present brief descriptions of two top quark analyses performed using D0 data from p{bar p} collisions at {radical}s = 1.96 TeV: the search for flavor-changing neutral-current couplings (FCNC) of the top quark with a charm or an up quark with the exchange of a gluon, and the search for the standard model production of single top quarks. The search for FCNC couplings of a gluon to the top quark is the first such analysis at hadron colliders. I describe the application of the Bayesian approach for comparing our physics models to the observed data in both analyses and, in one of them, to separate small signals from large backgrounds.

Jain, Supriya; /Oklahoma U.

2008-05-01T23:59:59.000Z

129

Measurement of the top-quark pair production cross-section in events with two leptons and bottom-quark jets using the full CDF data set  

E-Print Network (OSTI)

We present a measurement of the top-quark pair production cross-section in proton-antiproton collisions at $\\sqrt{s}$=1.96 TeV. The data were collected at the Fermilab Tevatron by the CDF II detector and correspond to an integrated luminosity of 8.8 fb$^{-1}$, representing the complete CDF Run II data set. We select events consistent with the production of top-quark pairs by requiring the presence of two reconstructed leptons, an imbalance in the total event transverse momentum, and jets. At least one jet is required to be identified as consistent with the fragmentation of a bottom quark using a secondary-vertex-finding algorithm. The 246 candidate events are estimated to have a signal purity of 91%. We measure a cross section of $\\sigma_{\\ttbar}$ = 7.09 $\\pm$ 0.84 pb, assuming a top-quark mass of 172.5 GeV/$c^{2}$. The results are consistent with the standard model as predicted by next-to-leading-order calculations.

CDF Collaboration

2013-04-30T23:59:59.000Z

130

Top pair production cross section at s**(1/2) = 1.96 TeV and a search for v + a current in top quark decay  

SciTech Connect

Possible effects from physics beyond the Standard Model have been investigated in top quark decays from a data sample enriched in t{bar t} events produced in p{bar p} collisions at {radical}s = 1.96 TeV with an integrated luminosity of approximately 700 pb{sup -1} and collected with the CDF II detector. The combined t{bar t} production cross section measurement 7.3 {+-} 0.9 pb agrees with the QCD NLO predictions: 6.7 {+-} 0.8 pb assuming m{sub top} = 175 GeV/c{sup 2}. The fraction of the V + A current in top quark decay, f{sub V+A}, is determined using the invariant mass of the charged lepton and the bottom quark jet in the decay chain t {yields} Wb {yields} {ell}{nu}b (where {ell} = e or {mu}). The measured value f{sub V+A} = - 0.06 {+-} 0.25 under the assumption m{sub top} = 175 GeV/c{sup 2} is in agreement with the Standard Model. They set an upper limit on f{sub V+A} of 0.29 at the 95% confidence level.

Cabrera, S.; /Valencia U., IFIC

2006-09-01T23:59:59.000Z

131

Quark-antiquark potential to order 1/m and heavy quark masses  

SciTech Connect

An updated heavy quark-antiquark potential is constructed by matching the short-distance perturbative part to long-distance lattice QCD results at an intermediate r scale. The static potential and the order 1/m potential are both analyzed in this way. Effects of order 1/m in charmonium and bottomonium spectra are discussed in comparison. Charm and bottom quark masses are deduced from the spectra and related to the quark masses of other schemes.

Laschka, Alexander; Kaiser, Norbert; Weise, Wolfram [Physik Department, Technische Universitaet Muenchen, D-85747 Garching (Germany)

2011-05-01T23:59:59.000Z

132

QCD Thermodynamics with an almost realistic quark mass spectrum  

E-Print Network (OSTI)

We will report on the status of a new large scale calculation of thermodynamic quantities in QCD with light up and down quarks corresponding to an almost physical light quark mass value and a heavier strange quark mass. These calculations are currently being performed on the QCDOC Teraflops computers at BNL. We will present new lattice calculations of the transition temperature and various susceptibilities reflecting properties of the chiral transition. All these quantities are of immediate interest for heavy ion phenomenology.

C. Schmidt

2006-01-25T23:59:59.000Z

133

Search for electroweak single top quark production in 1.96-TeV proton-antiproton collisions  

SciTech Connect

This thesis describes the first search for electroweak single top quark production in proton-antiproton collisions at a center of mass energy of 1.96 TeV. The data sample used for this analysis corresponds to 162 pb{sup -1} recorded by the upgraded Collider Detector at Fermilab. The search is performed by doing a classic maximum likelihood fit to the H{sub T} distribution in data. The kinematic variable H{sub T} is the scalar sum of transverse energies of all final state particles in the event. This variable has the advantage that its distribution looks very similar for both contributing (s-channel and t-channel) single top processes, but is different for background processes. The combination of both channels to one signal improves the sensitivity of the search. No significant evidence for electroweak single top quark production is found and we set an upper limit at the 95% confidence level on the combined single top quark production cross section of 17.8 pb.

Stelzer, Bernd; /Toronto U.

2005-01-01T23:59:59.000Z

134

Twisted mass QCD and the FNAL heavy quark formalism  

E-Print Network (OSTI)

At tree level, I discuss modifying the FNAL heavy quark formalism to include a twisted mass term. I find that at maximal twist the so called KLM factor is independent of the heavy mass.

Craig McNeile

2008-10-21T23:59:59.000Z

135

Top physics results at CDF  

SciTech Connect

The most recent results on top quark physics at CDF are reported. Measurements of cross-section and mass are presented, and the status of single top quark production searches are discussed. The results obtained from probing various top quark properties are also presented.

Vickey, Trevor; /Illinois U., Urbana

2005-05-01T23:59:59.000Z

136

Electroweak production of the top quark in the Run II of the D0 experiment  

SciTech Connect

The work exposed in this thesis deals with the search for electroweak production of top quark (single top) in proton-antiproton collisions at {radical}s = 1.96 TeV. This production mode has not been observed yet. Analyzed data have been collected during the Run II of the D0 experiment at the Fermilab Tevatron collider. These data correspond to an integrated luminosity of 370 pb{sup -1}. In the Standard Model, the decay of a top quark always produce a high momentum bottom quark. Therefore bottom quark jets identification plays a major role in this analysis. The large lifetime of b hadrons and the subsequent large impact parameters relative to the interaction vertex of charged particle tracks are used to tag bottom quark jets. Impact parameters of tracks attached to a jet are converted into the probability for the jet to originate from the primary vertex. This algorithm has a 45% tagging efficiency for a 0.5% mistag rate. Two processes (s and t channels) dominate single top production with slightly different final states. The searched signature consists in 2 to 4 jets with at least one bottom quark jet, one charged lepton (electron or muon) and missing energy accounting for a neutrino. This final state is background dominated and multivariate techniques are needed to separate the signal from the two main backgrounds: associated production of a W boson and jets and top quarks pair production. The achieved sensitivity is not enough to reach observation and we computed upper limits at the 95% confidence level at 5 pb (s-channel) and 4.3 pb (t-channel) on single top production cross-sections.

Clement, Benoit; /Strasbourg, IReS

2006-04-01T23:59:59.000Z

137

Measurement of electroweak single top quark production in proton-antiproton collisions at 1.96 TeV  

Science Conference Proceedings (OSTI)

The top quark is an extremely massive fundamental particle that is predominantly produced in pairs at particle collider experiments. The Standard Model of particle physics predicts that top quarks can also be produced singly by the electroweak force; however, this process is more difficult to detect because it occurs at a smaller rate and is more difficult to distinguish from background processes. The cross section of this process is related to the Cabbibo-Kobayashi-Maskawa matrix element |V{sub tb}|, and measurement of the single top quark production cross section is currently the only method to directly measure this quantity without assuming the number of generations of fermions. This thesis describes a measurement of the cross section of electroweak single top quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. This analysis uses 2.2 fb{sup -1} of integrated luminosity recorded by the Collider Detector at Fermilab. The search is performed using a matrix element method which calculates the differential cross section for each event for several signal and background hypotheses. These numbers are combined into a single discriminant and used to construct templates from Monte Carlo simulation. A maximum likelihood fit to the data distribution gives a measurement of the cross section. This analysis measures a value of 2.2{sub -0.7}{sup +0.8} pb, which corresponds to a value of |V{sub tb}| = 0.88{sub -0.14}{sup +0.16}experimental{+-}0.7(theoretical). The probability that this result originates from a background fluctuation in the absence of single top production (p-value) is 0.0003, which is equivalent to 3.4 standard deviations in Gaussian statistics. The expected (median) p-value as estimated from pseudo-experiments for this analysis is 0.000003, which corresponds to 4.5 standard deviations in Gaussian statistics.

Dong, Peter Joseph; /UCLA

2008-05-01T23:59:59.000Z

138

Measurement of the electroweak top quark production cross section and the CKM matrix element Vtb with the D0 experiment  

SciTech Connect

At particle accelerators the Standard Model has been tested and will be tested further to a great precision. The data analyzed in this thesis have been collected at the world's highest energetic-collider, the Tevatron, located at the Fermi National Accelerator Laboratory (FNAL) in the vicinity of Chicago, IL, USA. There, protons and antiprotons are collided at a center-of-mass energy of {radical}s = 1.96 TeV. The discovery of the top quark was one of the remarkable results not only for the CDF and D0 experiments at the Tevatron collider, but also for the Standard Model, which had predicted the existence of the top quark because of symmetry arguments long before already. Still, the Tevatron is the only facility able to produce top quarks. The predominant production mechanism of top quarks is the production of a top-antitop quark pair via the strong force. However, the Standard Model also allows the production of single top quarks via the electroweak interaction. This process features the unique opportunity to measure the |V{sub tb}| matrix element of the Cabbibo-Kobayashi-Maskawa (CKM) matrix directly, without assuming unitarity of the matrix or assuming that the number of quark generations is three. Hence, the measurement of the cross section of electroweak top quark production is more than the technical challenge to extract a physics process that only occurs one out of ten billion collisions. It is also an important test of the V-A structure of the electroweak interaction and a potential window to physics beyond the Standard Model in the case where the measurement of |V{sub tb}| would result in a value significantly different from 1, the value predicted by the Standard Model. At the Tevatron two production processes contribute significantly to the production of single top quarks: the production via the t-channel, also called W-gluon fusion, and the production via the s-channel, known as well as W* process. This analysis searches for the combined s+t channel production cross section, assuming the ratio of s-channel production over t-channel production is realized in nature as predicted by the Standard Model. A data set of approximately 1 fb{sup -1} is analyzed, the data set used by the D0 collaboration to claim evidence for single top quark production. Events with two, three, and four jets are used in the analysis if they contain one or two jets that were tagged as originating from the decay of a b hadron, an isolated muon or electron, and a significant amount of missing transverse energy. This selection of events follows the signature that the single top quark events are expected to show in the detector. In the meantime, both collaborations D0 and CDF have analyzed a larger data set and have celebrated the joint observation of single top quark production. The novelty of the analysis presented here is the way discriminating observables are determined. A so-called Multi-Process Factory evaluates each event under several hypotheses. A common analysis technique for example in top quark properties studies is to reconstruct the intermediate particles in the decay chain of the signal process from the final state objects measured in the various subdetectors. An essential part of such a method is to resolve the ambiguities that arise in the assignment of the final state objects to the partons of the decay chain. In a Multi-Process Factory this approach is extended and not only the decay chain of the signal process is reconstructed, but also the decay chains of the most important background processes. From the numerous possible event configurations for each of the signal and background decay chains the most probable configuration is selected based on a likelihood measure. Properties of this configuration, such as mass of the reconstructed top quark, are then used in a multivariate analysis technique to separate the expected signal contribution from the background processes. The technique which is used is called Boosted Decision Trees and has only recently been introduced in high energy physics analyses. A Bayesian approach is use

Kirsch, Matthias; /Aachen, Tech. Hochsch.

2009-06-01T23:59:59.000Z

139

Investigation of Electroweak Production of the Top Quark at the LHC  

E-Print Network (OSTI)

This thesis presents a study of the prospects of measuring electroweak production of the top quark at the LHC. The study of the top quark is a highly topical subject as we expect significant numbers of top quarks at the LHC which will enable us to conduct precision measurements of the properties of the top. The t-channel "single top" is a relatively rare mode of top production but with it we can probe the spin structure of the Wtb vertex in the weak interaction at an unprecedented energy scale through the measurement of the top polarisation. Analysis strategies and computing tools were developed and tested extensively. The study was performed using the signal and background events modelled with Monte Carlo generators, many of which have been newly developed for the LHC analyses. Full and fast simulation of the ATLAS detector was performed to obtain realistic estimates of the sensitivity of the measurements. A new fully fledged analysis framework, "EventView" was developed for the ATLAS collaboration to process these data at the first level of analysis. Parameterised vertex tagging was developed to estimate the level of background for this analysis and a maximum likelihood fit was used for the precise extraction of the top polarisation. In the high energy hadronic environment at the LHC, the estimation of possible systematic errors, both experimental and theoretical, needs to be carefully considered. Important elements of the systematic errors were investigated and the main contributions were evaluated.

Akira Shibata

2008-04-23T23:59:59.000Z

140

Higher-order soft gluon corrections in single top quark production at the CERN LHC  

SciTech Connect

I present a calculation of soft-gluon corrections to single top-quark production in pp collisions at the LHC via the standard model partonic processes in the t and s channels and associated top quark and W boson production. Higher-order soft-gluon corrections through next-to-next-to-next-to-leading order (NNNLO) are calculated at next-to-leading logarithmic (NLL) accuracy. The soft-gluon corrections in the s channel and in tW production are large and dominant, while in the t channel they are not a good approximation of the complete QCD corrections.

Kidonakis, Nikolaos [Kennesaw State University, Physics 1202, 1000 Chastain Road, Kennesaw, Georgia 30144-5591 (United States)

2007-04-01T23:59:59.000Z

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141

Investigation of Electroweak Production of the Top Quark at the LHC  

E-Print Network (OSTI)

This thesis presents a study of the prospects of measuring electroweak production of the top quark at the LHC. The study of the top quark is a highly topical subject as we expect significant numbers of top quarks at the LHC which will enable us to conduct precision measurements of the properties of the top. The t-channel ``single top'' is a relatively rare mode of top production but with it we can probe the spin structure of the Wtb vertex in the weak interaction at an unprecedented energy scale through the measurement of the top polarisation. Analysis strategies and computing tools were developed and tested extensively. The study was done using the signal and background events modelled with Monte Carlo generators, many of which have been newly developed for the LHC analysis. Full and fast simulation of the \\ATLAS\\ detector were performed to obtain realistic estimates of the sensitivity of the measurements. A new fully fledged analysis framework, ``\\EventView'' was developed for the \\ATLAS\\ collaboration to p...

Shibata, Akira; Thompson, Graham

2007-01-01T23:59:59.000Z

142

Search for pair production of scalar top quarks in jets and missing transverse energy channel with the D0 detector  

SciTech Connect

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.

Shamim, Mansoora; /Kansas State U.

2008-05-01T23:59:59.000Z

143

Debye mass and heavy quark potential in a PNJL quark plasma  

SciTech Connect

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.

Jankowski, J., E-mail: jakubj@ift.uni.wroc.pl; Blaschke, D., E-mail: blaschke@ift.uni.wroc.pl [University of Wroclaw, Institute for Theoretical Physics (Poland)

2012-07-15T23:59:59.000Z

144

ttbar+large missing energy from top-quark partners: a comprehensive study at NLO QCD  

E-Print Network (OSTI)

We perform a detailed study of top-quark partner production in the ttbar plus large missing energy final-state at the LHC, presenting results for both scalar and fermionic top-quark partners in the semi-leptonic and dileptonic decay modes of the top quarks. We compare the results of several simulation tools: leading-order matrix elements, next-to-leading order matrix elements, leading-order plus parton shower simulations, and merged samples that contain the signal process with an additional hard jet radiated. We find that predictions from leading-order plus parton shower simulations can significantly deviate from NLO QCD or LO merged samples and do not correctly model the kinematics of the ttbar + ETmiss signature. They are therefore not a good framework for modeling this new physics signature. On the other hand, the acceptances obtained with a merged sample of the leading-order process together with the radiation of an additional hard jet are in agreement with the NLO predictions. We also demonstrate that the scale variation of the inclusive cross section, plus that of the acceptance, does not accurately reflect the uncertainty of the cross section after cuts, which is typically larger. We show the importance of including higher-order QCD corrections when using kinematic distributions to determine the spin of the top-quark partner.

Radja Boughezal; Markus Schulze

2013-09-09T23:59:59.000Z

145

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

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.

Aaltonen, T.; /Helsinki Inst. of Phys.; Adelman, J.; /Chicago U., EFI; Alvarez Gonzalez, B.; /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U.; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.; /Fermilab; Apresyan, A.; /Purdue U. /Waseda U.

2010-01-01T23:59:59.000Z

146

Measurement of top quark polarization in top-antitop events from proton-proton collisions at ?s = 7 TeV using the ATLAS detector  

E-Print Network (OSTI)

This Letter presents measurements of the polarization of the top quark in top–antitop quark pair events, using 4.7 fb$^{¯1}$ of proton–proton collision data recorded with the ATLAS detector at the Large Hadron Collider at ?s = 7 TeV. Final states containing one or two isolated leptons (electrons or muons) and jets are considered. Two measurements of $\\alpha_l P$, the product of the leptonic spin-analyzing power and the top quark polarization, are performed assuming that the polarization is introduced by either a CP conserving (CPC) or a CP violating (CPV) production process. The measurements obtained, $\\alpha_l P_{CPC} = ?0.035± 0.014(stat) ± 0.037(syst)$ and $\\alpha_l P_{CPV} = 0.020 ± 0.016(stat)^{+0.013} _{-0.017}(syst)$, are in good agreement with the Standard Model prediction of negligible top quark polarization.

Aad, Georges; Abbott, Brad; Abdallah, Jalal; Abdel Khalek, Samah; Abdinov, Ovsat; Aben, Rosemarie; Abi, Babak; Abolins, Maris; AbouZeid, Ossama; Abramowicz, Halina; Abreu, Henso; Abulaiti, Yiming; Acharya, Bobby Samir; Adamczyk, Leszek; Adams, David; Addy, Tetteh; Adelman, Jahred; Adomeit, Stefanie; Adye, Tim; Aefsky, Scott; Agatonovic-Jovin, Tatjana; Aguilar-Saavedra, Juan Antonio; Agustoni, Marco; Ahlen, Steven; Ahmad, Ashfaq; Ahsan, Mahsana; Aielli, Giulio; Åkesson, Torsten Paul Ake; Akimoto, Ginga; Akimov, Andrei; Alam, Muhammad Aftab; Albert, Justin; Albrand, Solveig; Alconada Verzini, Maria Josefina; Aleksa, Martin; Aleksandrov, Igor; Alessandria, Franco; Alexa, Calin; Alexander, Gideon; Alexandre, Gauthier; Alexopoulos, Theodoros; Alhroob, Muhammad; Aliev, Malik; Alimonti, Gianluca; Alio, Lion; Alison, John; Allbrooke, Benedict; Allison, Lee John; Allport, Phillip; Allwood-Spiers, Sarah; Almond, John; Aloisio, Alberto; Alon, Raz; Alonso, Alejandro; Alonso, Francisco; Altheimer, Andrew David; Alvarez Gonzalez, Barbara; Alviggi, Mariagrazia; Amako, Katsuya; Amaral Coutinho, Yara; Amelung, Christoph; Ammosov, Vladimir; Amor Dos Santos, Susana Patricia; Amorim, Antonio; Amoroso, Simone; Amram, Nir; Anastopoulos, Christos; Ancu, Lucian Stefan; Andari, Nansi; Andeen, Timothy; Anders, Christoph Falk; Anders, Gabriel; Anderson, Kelby; Andreazza, Attilio; Andrei, George Victor; Anduaga, Xabier; Angelidakis, Stylianos; Anger, Philipp; Angerami, Aaron; Anghinolfi, Francis; Anisenkov, Alexey; Anjos, Nuno; Annovi, Alberto; Antonaki, Ariadni; Antonelli, Mario; Antonov, Alexey; Antos, Jaroslav; Anulli, Fabio; Aoki, Masato; Aperio Bella, Ludovica; Apolle, Rudi; Arabidze, Giorgi; Aracena, Ignacio; Arai, Yasuo; Arce, Ayana; Arfaoui, Samir; Arguin, Jean-Francois; Argyropoulos, Spyridon; Arik, Engin; Arik, Metin; Armbruster, Aaron James; Arnaez, Olivier; Arnal, Vanessa; Arslan, Ozan; Artamonov, Andrei; Artoni, Giacomo; Asai, Shoji; Asbah, Nedaa; Ask, Stefan; Åsman, Barbro; Asquith, Lily; Assamagan, Ketevi; Astalos, Robert; Astbury, Alan; Atkinson, Markus; Atlay, Naim Bora; Auerbach, Benjamin; Auge, Etienne; Augsten, Kamil; Aurousseau, Mathieu; Avolio, Giuseppe; Axen, David; Azuelos, Georges; Azuma, Yuya; Baak, Max; Bacci, Cesare; Bach, Andre; Bachacou, Henri; Bachas, Konstantinos; Backes, Moritz; Backhaus, Malte; Backus Mayes, John; Badescu, Elisabeta; Bagiacchi, Paolo; Bagnaia, Paolo; Bai, Yu; Bailey, David; Bain, Travis; Baines, John; Baker, Oliver Keith; Baker, Sarah; Balek, Petr; Balli, Fabrice; Banas, Elzbieta; Banerjee, Swagato; Banfi, Danilo; Bangert, Andrea Michelle; Bansal, Vikas; Bansil, Hardeep Singh; Barak, Liron; Baranov, Sergei; Barber, Tom; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Bardin, Dmitri; Barillari, Teresa; Barisonzi, Marcello; Barklow, Timothy; Barlow, Nick; Barnett, Bruce; Barnett, Michael; Baroncelli, Antonio; Barone, Gaetano; Barr, Alan; Barreiro, Fernando; Barreiro Guimarães da Costa, João; Bartoldus, Rainer; Barton, Adam Edward; Bartsch, Valeria; Bassalat, Ahmed; Basye, Austin; Bates, Richard; Batkova, Lucia; Batley, Richard; Battistin, Michele; Bauer, Florian; Bawa, Harinder Singh; Beale, Steven; Beau, Tristan; Beauchemin, Pierre-Hugues; Beccherle, Roberto; Bechtle, Philip; Beck, Hans Peter; Becker, Anne Kathrin; Becker, Sebastian; Beckingham, Matthew; Becks, Karl-Heinz; Beddall, Andrew; Beddall, Ayda; Bedikian, Sourpouhi; Bednyakov, Vadim; Bee, Christopher; Beemster, Lars; Beermann, Thomas; Begel, Michael; Belanger-Champagne, Camille; Bell, Paul; Bell, William; Bella, Gideon; Bellagamba, Lorenzo; Bellerive, Alain; Bellomo, Massimiliano; Belloni, Alberto; Beloborodova, Olga; Belotskiy, Konstantin; Beltramello, Olga; Benary, Odette; Benchekroun, Driss; Bendtz, Katarina; Benekos, Nektarios; Benhammou, Yan; Benhar Noccioli, Eleonora; Benitez Garcia, Jorge-Armando; Benjamin, Douglas; Bensinger, James; Benslama, Kamal; Bentvelsen, Stan; Berge, David; Bergeaas Kuutmann, Elin; Berger, Nicolas; Berghaus, Frank; Berglund, Elina; Beringer, Jürg; Bernard, Clare; Bernat, Pauline; Bernhard, Ralf; Bernius, Catrin; Bernlochner, Florian Urs; Berry, Tracey; Bertella, Claudia; Bertolucci, Federico; Besana, Maria Ilaria; Besjes, Geert-Jan; Bessidskaia, Olga; Besson, Nathalie; Bethke, Siegfried; Bhimji, Wahid; Bianchi, Riccardo-Maria; Bianchini, Louis; Bianco, Michele; Biebel, Otmar; Bieniek, Stephen Paul; Bierwagen, Katharina; Biesiada, Jed; Biglietti, Michela; Bilbao De Mendizabal, Javier; Bilokon, Halina; Bindi, Marcello; Binet, Sebastien; Bingul, Ahmet; Bini, Cesare; Bittner, Bernhard

2013-01-01T23:59:59.000Z

147

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

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.

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

2008-05-01T23:59:59.000Z

148

Top Quark Produced Through the Electroweak Force: Discovery Using the Matrix Element Analysis and Search for Heavy Gauge Bosons Using Boosted Decision Trees  

Science Conference Proceedings (OSTI)

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}| 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.

Pangilinan, Monica; /Brown U.

2010-02-01T23:59:59.000Z

149

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

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.

Pangilinan, Monica; /Brown U.

2010-02-01T23:59:59.000Z

150

Model-independent extraction of $|V_{tq}|$ matrix elements from top-quark measurements at hadron colliders  

E-Print Network (OSTI)

Current methods to extract the quark-mixing matrix element $|V_{tb}|$ from single-top production measurements assume that $|V_{tb}|\\gg |V_{td}|, |V_{ts}|$: top quarks decay into $b$ quarks with 100% branching fraction, s-channel single-top production is always accompanied by a $b$ quark and initial-state contributions from $d$ and $s$ quarks in the $t$-channel production of single top quarks are neglected. Triggered by a recent measurement of the ratio $R=\\frac{|V_{tb}|^{2}}{|V_{td}|^{2}+|V_{ts}|^{2}+|V_{tb}|^{2}}=0.90 \\pm 0.04$ performed by the D0 collaboration, we consider a $|V_{tb}|$ extraction method that takes into account non zero d- and s-quark contributions both in production and decay. We propose a strategy that allows to extract consistently and in a model-independent way the quark mixing matrix elements $|V_{td}|$, $|V_{ts}|$, and $|V_{tb}|$ from the measurement of $R$ and from single-top measured event yields. As an illustration, we apply our method to the Tevatron data using a CDF analysis of the measured single-top event yield with two jets in the final state one of which is identified as a $b$-quark jet. We constrain the $|V_{tq}|$ matrix elements within a four-generation scenario by combining the results with those obtained from direct measurements in flavor physics and determine the preferred range for the top-quark decay width within different scenarios.

H. Lacker; A. Menzel; F. Spettel; D. Hirschbühl; J. Lück; F. Maltoni; W. Wagner; M. Zaro

2012-02-21T23:59:59.000Z

151

Tracking Down the Top Quark Forward-Backward Asymmetry with Monotops  

E-Print Network (OSTI)

We revisit the possibility that the top quark forward-backward asymmetry arises from the on-shell production and decay of scalar top partners to top-antitop pairs with missing transverse energy. Although the asymmetry is produced by t-channel exchange of a light mediator, the model remains unconstrained by low energy atomic parity violation tests. An interesting connection to the active neutrino sector through a Type-I seesaw operator helps to evade stringent monojet constraints and opens up a richer collider phenomenology. After performing a global fit to top data from both the Tevatron and the LHC, we obtain a viable region of parameter space consistent with all phenomenological and collider constraints. We also discuss the discovery potential of a predicted monotop signal and related lepton charge asymmetry at the LHC.

Abhishek Kumar; John N. Ng; Andrew Spray; Peter T. Winslow

2013-08-16T23:59:59.000Z

152

Quark mass variation constraints from Big Bang nucleosynthesis  

SciTech Connect

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 model-independent way we use lattice QCD data and an hierarchy of effective field theories. We find that the measured {sup 4}He abundances put a bound of {delta}-1% {approx}< m{sub q}/m{sub 1} {approx}< 0.7%. The effect of quark mass variations on the deuterium abundances can be largely compensated by changes of the baryon-to-photon ratio {eta}. Including the bounds on the variation of {eta} coming from WMAP results and some additional assumptions narrows the range of allowed values of {delta}m{sub q}/m{sub q} somewhat.

Bedaque, P; Luu, T; Platter, L

2010-12-13T23:59:59.000Z

153

Search for the Standard Model Higgs Boson Produced in Association with Top Quarks Using the Full CDF Data Set  

E-Print Network (OSTI)

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[superscript -1], collected by the ...

Gomez-Ceballos, Guillelmo

154

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

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.

Aaltonen, T.; /Helsinki Inst. of Phys.; Adelman, J.; /Yale U.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U. /Fermilab; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Arisawa, T.; /Waseda U. /Dubna, JINR

2012-03-01T23:59:59.000Z

155

Top Event  

NLE Websites -- All DOE Office Websites (Extended Search)

evento Top Volver Principal ESTOY PERDIDO El quark top --> un quark bottom y un bosn W; luego el W+ --> e+ ms un neutrino, y el quark bottom (que emerge como un antimesn B...

156

The mass distribution of quark matter  

E-Print Network (OSTI)

We analyze lattice QCD results on the equation of state in terms of infinitely many non-interacting massive ideal gas components. We find that the entire pressure-temperature curve can be described by a temperature independent mass distribution at vanishing chemical potential. We collect strong indications for a mass gap in this distribution, conjectured to be related confinement.

Biro, T S; Van, P; Zimányi, J

2006-01-01T23:59:59.000Z

157

Quarks  

NLE Websites -- All DOE Office Websites (Extended Search)

zusammengesetzt sind. Es gibt sechs Quarks, aber die Physiker reden lieber von drei Quark-paaren: updown, charmstrange, and topbottom. (Zu jedem Quark existiert ein...

158

Measurement of the charge asymmetry in top-quark pair production in proton-proton collisions at sqrt(s) = 7 TeV  

SciTech Connect

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.

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.

2011-12-01T23:59:59.000Z

159

SUSY-induced FCNC top-quark processes at the Large Hadron Collider  

E-Print Network (OSTI)

We systematically calculate various flavor-changing neutral-current top-quark processes induced by supersymmetry at the Large Hadron Collider, which include five decay modes and six production channels. To reveal the characteristics of these processes, we first compare the dependence of the rates for these channels on the relevant supersymmetric parameters, then we scan the whole parameter space to find their maximal rates, including all the direct and indirect current experimental constraints on the scharm-stop flavor mixings. We find that, under all these constraints, only a few channels, through cg->t at parton-level and t-> ch, may be observable at the Large Hadron Collider.

J. J. Cao; G. Eilam; M. Frank; K. Hikasa; G. L. Liu; I. Turan; J. M. Yang

2007-02-26T23:59:59.000Z

160

Search for the standard model Higgs boson produced in association with top quarks using the full CDF data set  

E-Print Network (OSTI)

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 inverse fb, 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 --> lepton + missing transverse energy + jets). For a Higgs boson mass of 125 GeV, 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.

The CDF Collaboration

2012-08-13T23:59:59.000Z

Note: This page contains sample records for the topic "top quark mass" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Search for the standard model Higgs boson produced in association with top quarks using the full CDF data set  

Science Conference Proceedings (OSTI)

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.

Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U. /Fermilab; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Arisawa, T.; /Waseda U.; Artikov, A.; /Dubna, JINR /Texas A-M

2012-08-01T23:59:59.000Z

162

Top Physics at CDF  

Science Conference Proceedings (OSTI)

We present the recent results of top-quark physics using up to 6 fb{sup -1} of p{bar p} collisions at a center of mass energy of {radical}s = 1.96 TeV analyzed by the CDF collaboration. Thanks to this large data sample, precision top quark measurements are now a reality at the Tevatron. Further, several new physics signals could appear in this large dataset. We will present the latest measurements of top quark intrinsic properties as well as direct searches for new physics in the top sector.

Moon, Chang-Seong

2011-06-01T23:59:59.000Z

163

Measurement of the W-boson helicity fractions in top-quark decays at CDF  

SciTech Connect

We present a measurement of the fractions F{sub 0} and F{sub +} of longitudinally polarized and right-handed W bosons in top-quark decays using data collected with the CDF II detector. The data set used in the analysis corresponds to an integrated luminosity of approximately 955 pb{sup -1}. We select t{bar t} candidate events with one lepton, at least four jets, and missing transverse energy. Our helicity measurement uses the decay angle {theta}*, which is defined as the angle between the momentum of the charged lepton in the W boson rest-frame and the W momentum in the top-quark rest-frame. The cos{theta}* distribution in the data is determined by full kinematic reconstruction of the t{bar t} candidates. We find F{sub 0}= 0.59 {+-} 0.12(stat){sup +0.07}{sub -0.06}(syst) and F{sub +}=-0.03 {+-} 0.06(stat){sup +0.04}{sub -0.03}(syst), which is consistent with the standard model prediction. We set an upper limit on the fraction of right-handed W bosons of F{sub +} {le} 0.10 at the 95% confidence level.

Chwalek, Thorsten; /Karlsruhe U., EKP

2007-05-01T23:59:59.000Z

164

Searches for New Physics in Top Decays at D0  

Science Conference Proceedings (OSTI)

The Tevatron proton-antiproton collider at Fermilab with its centre of mass energy of 1.96 TeV allows for pair production of top quarks and the study of top quark decay properties. This report reflects the current status of measurements of the W boson helicity in top quark decays and the ratio of top quark branching fractions as well as searches for neutral current top quark decays and pair production of fourth generation t' quarks, performed by the D0 Collaboration utilising datasets of up to 5.4 fb{sup -1}.

Pleier, Marc-Andre; /Brookhaven

2011-08-01T23:59:59.000Z

165

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

DOE Data Explorer (OSTI)

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. In addition, the user can see live event displays from the current Run II for both CDF and DZero experiments at http://www.fnal.gov/pub/now/live_events/index.html. Another interesting offering from the D0 groups at Fermilab is the large collection of "Plain English Summaries" of their published reports and papers. These Summaries are excellent for layman's understanding of the high energy physics research done at Fermilab and can serve as introductions to the published papers themselves. The Summaries are at http://www-d0.fnal.gov/public/pubs/d0_physics_summaries.html for Run I and http://www-d0.fnal.gov/Run2Physics/WWW/results/summary.htm for Run II.

None

166

Theoretical top quark cross section at the Fermilab Tevatron and the CERN LHC  

Science Conference Proceedings (OSTI)

We present results for the top quark pair cross section at the Tevatron and the LHC. We use the resummed double differential cross section, employing the fully kinematics-dependent soft-anomalous-dimension matrices, to calculate the soft-gluon contributions at next-to-next-to-leading order (NNLO). We improve and update our previous estimates by refining our methods, including further subleading terms, and employing the most recent parton distribution function sets. The NNLO soft corrections significantly enhance the NLO cross section while considerably reducing the scale dependence. We provide a detailed discussion of all theoretical uncertainties in our calculation, including kinematics, scale, and parton distribution uncertainties, and clarify the differences between our work and other approaches in the literature.

Kidonakis, Nikolaos [Kennesaw State University, Physics 1202, 1000 Chastain Road, Kennesaw, Georgia 30144-5591 (United States); Vogt, Ramona [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Physics Department, University of California at Davis, Davis, California 95616 (United States)

2008-10-01T23:59:59.000Z

167

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

SciTech Connect

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.

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.

2012-06-27T23:59:59.000Z

168

Production of single top-quark final states at the LHC from supersymmetric FCNC interactions  

E-Print Network (OSTI)

We discuss the production of single top-quark final states by direct supersymmetric flavor-changing interactions at the LHC. The total cross section pp(gg)->t\\bar{c}+\\bar{t}c is computed at the 1-loop order within the unconstrained MSSM. We prove that SUSY-QCD effects may furnish sizeable production rates amounting up to barely 10^5 t\\bar{c}(c\\bar{t}) events per 100 fb^{-1} of integrated luminosity, in full compliance with the stringent low-energy constraints from b->s gamma. Furthermore, we show that the cooperative SUSY-EW effects can be sizeable on their own, regardless of the SUSY-QCD contribution, with maximum production rates of the order of 10^3 events per 100 fb^{-1}. Owing to the fact that FCNC production of electrically neutral heavy-quark pairs is virtually absent within the SM, we conclude that the observation of such pp(gg)->t\\bar{c}+\\bar{t}c processes at the LHC could lead to evidence of new physics - of likely supersymmetric nature.

David Lopez-Val; Jaume Guasch; Joan Sola

2008-01-16T23:59:59.000Z

169

Measurements of the top quark pair production cross section and an estimate of the D0 silicon detector lifetime  

SciTech Connect

This thesis presents two measurements of the top quark pair production cross section at {radical}s = 1:96 TeV using data from the D0 experiment. Both measurements are performed in the dilepton final state and make use of secondary vertex b-tagging.

Strandberg, Sara; /Stockholm U.

2007-03-01T23:59:59.000Z

170

Top Production  

NLE Websites -- All DOE Office Websites (Extended Search)

Top Principal ESTOY PERDIDO!!! Top Principal ESTOY PERDIDO!!! Protón + Antiprotón --> Top + Antitop Un quark (perteneciente a un protón) y un antiquark (perteneciente a un antiprotón), colisionando a alta energía, pueden aniquilarse para producir un quark top y un antiquark top, los cuales decaen luego hacia otras partículas. Cuadro 1: un quark de un protón y un antiquark de un antiprotón se precipitan uno al encuentro del otro. Cuadro 2: los quarks colisionan y se aniquilan.... Cuadro 3: ...en gluones virtuales. Cuadro 4: de la nube de gluones emergen un quark top y un antiquark top. Cuadro 5: los quarks comienzan separarse, estirando el campo de fuerza de color (campo de gluones) entre ambos. Cuadro 6: antes de que el quark top y el antiquark top se hayan separado mucho, ambos decaen hacia un quark bottom y un antiquark bottom

171

QCD sum rule determination of the charm-quark mass  

Science Conference Proceedings (OSTI)

QCD sum rules involving mixed inverse moment integration kernels are used in order to determine the running charm-quark mass in the MS scheme. Both the high and the low energy expansion of the vector current correlator are involved in this determination. The optimal integration kernel turns out to be of the form p(s)=1-(s{sub 0}/s){sup 2}, where s{sub 0} is the onset of perturbative QCD. This kernel enhances the contribution of the well known narrow resonances, and reduces the impact of the data in the range s{approx_equal}20-25 GeV{sup 2}. This feature leads to a substantial reduction in the sensitivity of the results to changes in s{sub 0}, as well as to a much reduced impact of the experimental uncertainties in the higher resonance region. The value obtained for the charm-quark mass in the MS scheme at a scale of 3 GeV is m{sub c}(3 GeV)=987{+-}9 MeV, where the error includes all sources of uncertainties added in quadrature.

Bodenstein, S. [Centre for Theoretical and Mathematical Physics, University of Cape Town, Rondebosch 7700 (South Africa); Bordes, J.; Penarrocha, J. [Departamento de Fisica Teorica, Universitat de Valencia, and Instituto de Fisica Corpuscular, Centro Mixto Universitat de Valencia-CSIC (Spain); Dominguez, C. A. [Centre for Theoretical and Mathematical Physics, University of Cape Town, Rondebosch 7700 (South Africa); Department of Physics, Stellenbosch University, Stellenbosch 7600 (South Africa); Schilcher, K. [Institut fuer Physik, Johannes Gutenberg-Universitaet Staudingerweg 7, D-55099 Mainz (Germany)

2011-04-01T23:59:59.000Z

172

A "Muon Mass Tree" with alpha-quantized Lepton, Quark and Hadron Masses  

E-Print Network (OSTI)

A "muon mass tree" is displayed that contains the excitation systematics for accurately reproducing the masses of the six Standard Model quarks (u,d,s,c,b,t); the heavy leptons; the proton; the phi, J/Psi and Upsilon vector meson thrshold states; the Bc meson; and the mass-averaged W and Z gauge bosons, using a unified mass formalism based on the electron ground state. Multiples of an alpha-quantized 105.04 MeV fermion mass quantum reproduce the states below 12 GeV, and multiples of a doubly-alpha-quantized 14,394 Mev fermion mass quantum reproduce the W-Z and t states above 12 GeV, where alpha ~ 1/137 is the fine structure constant. Masses are additive, and the overall mass accuracy for these states is in the 1% range. A similar "pion mass tree" based on an alpha-quantized 70.03 MeV boson mass quantum accurately reproduces the pseudoscalar meson masses. The mass alpha-quantization follows from a corresponding experimental alpha-spacing of the long-lived particle lifetimes, which occur in well-defined lifetime groups that are each determined by a dominant Standard Model quark substate.

Malcolm H. Mac Gregor

2006-07-20T23:59:59.000Z

173

Top Produktion  

NLE Websites -- All DOE Office Websites (Extended Search)

Teilchenzerfall und -vernichtung Top Produktion Ein Quark (in einem Proton) und ein Antiquark (in einem Antiproton), welche mit grosser Energie zusammenstossen, knnen in ein top...

174

Quark  

NLE Websites -- All DOE Office Websites (Extended Search)

DeGrand (University of Colorado, Boulder) and B. Krusche (University of Basel). 14.1. Quantum numbers of the quarks Quarks are strongly interacting fermions with spin 12 and, by...

175

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

SciTech Connect

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.

Liu, Zhiyi; /Simon Fraser U.

2009-12-01T23:59:59.000Z

176

Model-independent measurement of t-channel single top quark production in p(p)over-bar collisions at,root s=1.96 TeV  

SciTech Connect

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.

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.

2011-11-17T23:59:59.000Z

177

Combination of CDF and D0 measurements of the W boson helicity in top quark decays  

E-Print Network (OSTI)

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^-1 of ppbar collisions collected during Run II of the Fermilab Tevatron Collider. Combining measurements that simultaneously determine the fractions of W bosons with longitudinal (f0) and right-handed (f+) helicities, we find f0 = 0.722 \\pm 0.081 [\\pm 0.062 (stat.) \\pm 0.052 (syst.)] and f+ = -0.033 \\pm 0.046 [\\pm 0.034 (stat.) \\pm 0.031 (syst.)]. Combining measurements where one of the helicity fractions is fixed to the value expected in the standard model, we find f0 = 0.682 \\pm 0.057 [\\pm 0.035 (stat.) \\pm 0.046 (syst.)] and f+ = -0.015\\pm0.035 [\\pm 0.018 (stat.) \\pm 0.030 (syst.)]. The results are consistent with standard model expectations.

Aaltonen, T; Abbott, B; Acharya, B S; Adams, M; Adams, T; Alexeev, G D; Alkhazov, G; Alton, A; González, B Álvarez; Alverson, G; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Appel, J A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Askew, A; Åsman, B; Atkins, S; Atramentov, O; Auerbach, B; Augsten, K; Aurisano, A; Avila, C; Azfar, F; Badaud, F; Badgett, W; Bae, T; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, S; Barbaro-Galtieri, A; Barberis, E; Baringer, P; Barnes, V E; Barnett, B A; Barreto, J; Barria, P; Bartlett, J F; Bartos, P; Bassler, U; Bauce, M; Bazterra, V; Bean, A; Bedeschi, F; Begalli, M; Behari, S; Belanger-Champagne, C; Bellantoni, L; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Beri, S B; Bernardi, G; Bernhard, R; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhatia, S; Bhatnagar, V; Bhatti, A; Bhat, P C; Bisello, D; Bizjak, I; Bland, K R; Blazey, G; Blessing, S; Bloom, K; Blumenfeld, B; Bocci, A; Bodek, A; Boehnlein, A; Boline, D; Boos, E E; Borissov, G; Bortoletto, D; Bose, T; Boudreau, J; Boveia, A; Brandt, A; Brandt, O; Brigliadori, L; Brock, R; Bromberg, C; Brooijmans, G; Bross, A; Brown, D; Brown, J; Brucken, E; Bu, X B; Budagov, J; Budd, H S; Buehler, M; Buescher, V; Bunichev, V; Burdin, S; Burkett, K; Bussey, P; Buszello, C P; Buzatu, A; Calamba, A; Calancha, C; Camacho-Pérez, E; Camarda, S; Campanelli, M; Campbell, M; Canelli, F; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Casey, B C K; Castilla-Valdez, H; Castro, A; Catastini, P; Caughron, S; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chakrabarti, S; Chakraborty, D; Chan, K M; Chandra, A; Chapon, E; Chen, Y C; Chen, G; Chertok, M; Chevalier-Théry, S; Chiarelli, G; Chlachidze, G; Chlebana, F; Choi, S; Chokheli, D; Choudhary, B; Cho, D K; Cho, K; Cho, S W; Chung, W H; Chung, Y S; Cihangir, S; Ciocci, M A; Claes, D; Clarke, C; Clark, A; Clutter, J; Compostella, G; Convery, M E; Conway, J; Cooke, M; Cooper, W E; Corbo, M; Corcoran, M; Cordelli, M; Couderc, F; Cousinou, M -C; Cox, C A; Cox, D J; Crescioli, F; Croc, A; Cuevas, J; Culbertson, R; Cutts, D; d'Ascenzo, N; d'Errico, M; D'Onofrio, M; Dagenhart, D; Das, A; Datta, M; Davies, G; Déliot, F; Dell'Orso, M; Demina, R; Demortier, L; Deninno, M; Denisov, D; Denisov, S P; Desai, S; Deterre, C; DeVaughan, K; Devoto, F; de Barbaro, P; de Jong, S J; De La Cruz-Burelo, E; Diehl, H T; Diesburg, M; Ding, P F; Dittmann, J R; Di Canto, A; Di Ruzza, B; Dominguez, A; Donati, S; Dong, P; Dorigo, M; Dorigo, T; Dorland, T; Dubey, A; Dudko, L V; Duggan, D; Duperrin, A; Dutt, S; Dyshkant, A; Eads, M; Ebina, K; Edmunds, D; Elagin, A; Ellison, J; Elvira, V D; Enari, Y; Eppig, A; Erbacher, R; Errede, S; Ershaidat, N; Eusebi, R; Evans, H; Evdokimov, A; Evdokimov, V N; Facini, G; Farrington, S; Feindt, M; Ferbel, T; Feng, L; Fernandez, J P; Fiedler, F; Field, R; Filthaut, F; Fisher, W; Fisk, H E; Flanagan, G; Forrest, R; Fortner, M; Fox, H; Franklin, M; Frank, M J; Freeman, J C; Fuess, S; Funakoshi, Y; Furic, I; Gallinaro, M; Garcia, J E; Garcia-Bellido, A; García-Guerra, G A; Garfinkel, A F; Garosi, P; Gavrilov, V; Gay, P; Geng, W; Gerbaudo, D; Gerber, C E; Gerberich, H; Gerchtein, E; Gershtein, Y; Giagu, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Ginsburg, C M; Ginther, G; Giokaris, N; Giromini, P; Giurgiu, G; Glagolev, V; Glenzinski, D; Goldin, D; Gold, M; Goldschmidt, N; Golossanov, A; Golovanov, G; Gomez-Ceballos, G; Gomez, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Goussiou, A; Grannis, P D; Greder, S; Greenlee, H; Grenier, G; Grinstein, S; Gris, Ph; Grivaz, J -F; Grohsjean, A; Grosso-Pilcher, C; Grünendahl, S; Grünewald, M W; Guillemin, T; da Costa, J Guimaraes; Guo, F; Gutierrez, G; Gutierrez, P; Haas, A; Hagopian, S; Hahn, S R; Haley, J; Halkiadakis, E; Hamaguchi, A; Han, J Y; Han, L; Happacher, F; Hara, K; Harder, K; Hare, D; Hare, M; Harel, A; Harr, R F; Hatakeyama, K; Hauptman, J M; Hays, C; Hays, J; Head, T; Hebbeker, T; Heck, M; Hedin, D; Hegab, H; Heinrich, J; Heinson, A P; Heintz, U; Hensel, C; La Cruz, I Heredia-De; Herndon, M; Herner, K; Hesketh, G; Hewamanage, S; Hildreth, M D; Hirosky, R; Hoang, T; Hobbs, J D; Hocker, A; Hoeneisen, B; Hohlfeld, M; Hopkins, W; Horn, D; Hou, S; Howley, I; Hubacek, Z; Hughes, R E; Hurwitz, M; Husemann, U; Hussain, N; Hussein, M; Huston, J; Hynek, V; Iashvili, I; Ilchenko, Y; Illingworth, R; Introzzi, G; Iori, M; Ito, A S; Ivanov, A; Jabeen, S; Jaffré, M; James, E; Jamin, D; Jang, D; Jayasinghe, A; Jayatilaka, B; Jeon, E J; Jesik, R; Jindariani, S; Johns, K; Johnson, M; Jonckheere, A; Jones, M; Jonsson, P; Joo, K K; Joshi, J; Jun, S Y; Jung, A W; Junk, T R; Juste, A; Kaadze, K; Kajfasz, E; Kamon, T; Karchin, P E; Karmanov, D; Kasmi, A; Kasper, P A; Kato, Y; Katsanos, I; Kehoe, R

2012-01-01T23:59:59.000Z

178

Combination of CDF and D0 measurements of the $W$ boson helicity in top quark decays  

Science Conference Proceedings (OSTI)

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.

Aaltonen, T.; /Helsinki Inst. of Phys.; Abazov, V.M.; /Dubna, JINR; Abbott, B.; /Oklahoma U.; Acharya, B.S.; /Tata Inst.; Adams, M.; /Illinois U., Chicago; Adams, T.; /Florida State U.; Alexeev, G.D.; /Dubna, JINR; Alkhazov, G.; /St. Petersburg, INP; Alton, A.; /Augustana Coll., Sioux Falls /Michigan U.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Alverson, G.; /Northeastern U. /INFN, Padua

2012-02-01T23:59:59.000Z

179

QCD THERMODYNAMICS WITH NF=2+1 NEAR THE CONTINUUM LIMIT AT REALISTIC QUARK MASSES.  

Science Conference Proceedings (OSTI)

We report on our study of QCD thermodynamics with 2 + 1 flavors of dynamical quarks. In this proceeding we present several thermodynamic quantities and our recent calculation of the critical temperature. In order to investigate the thermodynamic properties of QCD near the continuum limit we adopt improved staggered (p4) quarks coupled with tree-level Symanzik improved glue on N{sub t} = 4 and 6 lattices. The simulations are performed with a physical value of the strange quark mass and light quark masses which are in the range of m{sub q}/m{sub s} = 0.05 - 0.4. The lightest quark mass corresponds to a pion mass of about 150 MeV.

UMEDA, T.

2006-07-23T23:59:59.000Z

180

Heavy flavour physics from top to bottom  

SciTech Connect

We review the status of heavy flavour physics at the Fermilab Tevatron collider by summarizing recent top quark and B physics results from CDF and D0. In particular we discuss the measurement of the top quark mass and top production cross section as well as B meson lifetimes and time dependent B{anti B} mixing results. An outlook of perspectives for top and B physics in Run II starting in 1999 is also given.

Paulini, M. [Lawrence Berkeley National Lab., CA (United States); CDF and D0 Collaboration

1998-02-01T23:59:59.000Z

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181

Quark-mass dependence of three-flavor QCD at zero and imaginary chemical potential  

E-Print Network (OSTI)

We draw the three-flavor phase diagram as a function of light and strange quark masses for both zero and imaginary quark-number chemical potential, using the Polyakov-loop extended Nambu--Jona-Lasinio model with an effective four-quark vertex depending on the Polyakov loop. The model prediction is consistent with 2+1 flavor lattice QCD prediction at zero chemical potential and with degenerate three-flavor lattice QCD prediction at imaginary chemical potential.

Sasaki, Takahiro; Kouno, Hiroaki; Yahiro, Masanobu

2011-01-01T23:59:59.000Z

182

Measurement of R = B(t?Wb)/B(t?Wq) in top-quark-pair decays using lepton+jets events and the full CDF run II dataset  

E-Print Network (OSTI)

We present a measurement of the ratio of the top-quark branching fractions R=B(t?Wb)/ B(t?Wq), where q represents quarks of type b, s, or d, in the final state with a lepton and hadronic jets. The measurement uses ?s=1.96??TeV ...

Gomez-Ceballos, Guillelmo

183

Combination of searches for anomalous top quark couplings with 5.4 fb(-1) of p(p)over-bar collisions  

SciTech Connect

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}.

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.

2012-07-09T23:59:59.000Z

184

Search for the Charged Higgs Boson in the Decays of Top Quark Pairs in the e? and ?? at ?s = 1.8 TeV  

E-Print Network (OSTI)

Top quark production offers the unique opportunity to search for a charged Higgs boson (H \\Sigma ), as the contribution from t ! H + b ! + b can be large in extensions of the Standard Model. We use results from a search for top quark pair production by the Collider Detector at Fermilab (CDF) in the e+E / T +jets and + E / T +jets signatures to set an upper limit on the branching ratio of B(t ! H + b). The upper limit is in the range 0.5 to 0.6 at 95% C.L. for H + masses in the range 60 to 160 GeV, assuming the branching ratio for H + ! 5 is 100% . The lepton is detected through its 1-prong and 3-prong hadronic decays. Typeset using REVT E X 6 Many extensions of the Standard Model (SM) include a Higgs sector with two Higgs doublets, resulting in the existence of charged (H \\Sigma ) as well as neutral (h, H 0 , A) Higgs bosons. The simplest extensions are the TwoHiggs Doublet Models (2HDMs) [1], in which the extension consists only of the extra doublet. In Type ...

T. Affolder; H. Akimoto; A. Akopian; M. G. Albrow; P. Amaral; S. R. Amendolia; D. Amidei; J. Antos; G. Apollinari; T. Arisawa; T. Asakawa; W. Ashmanskas; M. Atac

1999-01-01T23:59:59.000Z

185

Measurement of W-Boson Polarization in Top-quark Decay in ppbar Collisions at sqrt(s) = 1.96 TeV  

SciTech Connect

We report measurements of the polarization of W bosons from top-quark decays using 2.7 fb{sup -1} of p{bar p} collisions collected by the CDF II detector. Assuming a top-quark mass of 175 GeV/c{sup 2}, three measurements are performed. A simultaneous measurement of the fraction of longitudinal (f{sub 0}) and right-handed (f{sub +}) W bosons yields the model-independent results f{sub 0} = 0.88 {+-} 0.11(stat) {+-} 0.06(syst) and f{sub +} = -0.15 {+-} 0.07(stat) {+-} 0.06(syst) with a correlation coefficient of -0.59. A measurement of f{sub 0} (f{sub +}) constraining f{sub +} (f{sub 0}) to its standard model value of 0.0 (0.7) yields f{sub 0} = 0.70 {+-} 0.07(stat) {+-} 0.04(syst) (f{sub +} = 0.01 {+-} 0.02(stat) {+-} 0.05(syst)). All these results are consistent with standard model expectations.

Aaltonen, T.; /Helsinki Inst. of Phys.; Adelman, J.; /Chicago U., EFI; Alvarez Gonzalez, B.; /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U.; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.; /Fermilab; Apresyan, A.; /Purdue U. /Waseda U.

2010-03-01T23:59:59.000Z

186

Proteomics by FTICR Mass Spectrometry: Top Down and Bottom Up  

SciTech Connect

This review offers a broad overview of recent FTICR applications and technological developments in the field of proteomics, directed to a variety of people with different expertise and interests. Both the ''bottom-up'' (peptide level) and ''top-down'' (intact protein level) approaches will be covered and various related aspects will be discussed and illustrated with examples that are among the best available references in the literature. ''Bottom-up topics include peptide fragmentation, the AMT approach and DREAMS technology, quantitative proteomics, post-translational modifications, and special FTICR software focused on peptide and protein identification. Topics in the ''top-down'' part include various aspects of high-mass measurements, protein tandem mass spectrometry, protein confirmations, protein-protein complexes, as well as some esoteric applications that may become more practical in the coming years. Finally, examples of integrating both approaches and medical proteomics applications using FTICR will be provided, closing with an outlook of what may be coming our way sooner than later.

Bogdanov, Bogdan; Smith, Richard D.

2005-03-31T23:59:59.000Z

187

Masses of mesons with charm valence quarks from 2+1+1 flavor twisted mass lattice QCD  

E-Print Network (OSTI)

We present preliminary results of an ongoing lattice QCD computation of the spectrum of $D$ mesons and $D_s$ mesons and of charmonium using 2+1+1 flavors of twisted mass sea and valence quarks.

Martin Kalinowski; Marc Wagner

2013-04-30T23:59:59.000Z

188

Constraining a fourth generation of quarks: non-perturbative Higgs boson mass bounds  

E-Print Network (OSTI)

We present a non-perturbative determination of the upper and lower Higgs boson mass bounds with a heavy fourth generation of quarks from numerical lattice computations in a chirally symmetric Higgs-Yukawa model. We find that the upper bound only moderately rises with the quark mass while the lower bound increases significantly, providing additional constraints on the existence of a straight-forward fourth quark generation. We examine the stability of the lower bound under the addition of a higher dimensional operator to the scalar field potential using perturbation theory, demonstrating that it is not significantly altered for small values of the coupling of this operator. For a Higgs boson mass of $\\sim125\\mathrm{GeV}$ we find that the maximum value of the fourth generation quark mass is $\\sim300\\mathrm{GeV}$, which is already in conflict with bounds from direct searches.

John Bulava; Karl Jansen; Attila Nagy

2013-01-15T23:59:59.000Z

189

Stability window and mass-radius relation for magnetized strange quark stars  

E-Print Network (OSTI)

The stability of magnetized strange quark matter (MSQM) is investigated within the phenomenological MIT bag model, taking into account the variation of the relevant input parameters, namely, the strange quark mass, baryon density, magnetic field and bag parameter. We obtain that the energy per baryon decreases as the magnetic field increases, and its minimum value at vanishing pressure is lower than the value found for SQM. This implies that MSQM is more stable than non-magnetized SQM. Furthermore, the stability window of MSQM is found to be wider than the corresponding one of SQM. The mass-radius relation for magnetized strange quark stars is also derived in this framework.

R. Gonzalez Felipe; A. Perez Martinez

2008-12-01T23:59:59.000Z

190

Top Physics Review and Outlook  

E-Print Network (OSTI)

I review the status of the top quark, and look forward to three topics relevant to future top-quark physics; spin correlation, single-top-quark production, and unification.

S. Willenbrock

1996-08-22T23:59:59.000Z

191

CDF Top Physics  

DOE R&D Accomplishments (OSTI)

The authors present the latest results about top physics obtained by the CDF experiment at the Fermilab Tevatron collider. The data sample used for these analysis (about 110 pb{sup{minus}1}) represents almost the entire statistics collected by CDF during four years (1992--95) of data taking. This large data size has allowed detailed studies of top production and decay properties. The results discussed here include the determination of the top quark mass, the measurement of the production cross section, the study of the kinematics of the top events and a look at top decays.

Tartarelli, G. F.; CDF Collaboration

1996-05-00T23:59:59.000Z

192

Multilepton Signatures of the Higgs Boson through its Production in Association with a Top-quark Pair  

E-Print Network (OSTI)

We consider the possible production of the Higgs Boson in association with a top-quark pair and its subsequent decay into a tau-lepton pair or a W-boson pair. This process can give rise to many signatures of the Higgs boson. These signatures can have electrons, muons, tau jets, bottom jets and/or light flavour jets. We analyze the viability of some of these signatures. We will look at those signatures where the background is minimal. In particular, we explore the viability of the signatures "isolated 4 electron/muon" and "isolated 3 electron/muon + a jet" The jet can be due to a light flavour quark/gluon, a bottom quark, or a tau lepton. Of all these signatures, we find that "isolated 3 electron/muon + a tau jet", with an extra bottom jet, can be an excellent signature of this mode of the Higgs boson production. We show that this signature may be visible within a year, once the Large Hadron Collider (LHC) restarts. Some of the other signatures would also be observable after the LHC accumulates sufficient luminosity.

Pankaj Agrawal; Somnath Bandyopadhyay; Siba Prasad Das

2013-08-14T23:59:59.000Z

193

Search for a heavy top t' to Wq in top events  

SciTech Connect

We present a search for a massive quark (t{prime}) decaying to Wq and thus mimicking the top quark decay signature in data collected by the CDF II detector corresponding to 2.8 fb{sup -1}. We use the reconstructed mass of the t{prime} quark and the scalar sum of the transverse energies in the event to discriminate possible new physics from Standard Model processes, and set limits on a standard 4th generation t{prime} quark.

Cox, David

2009-10-01T23:59:59.000Z

194

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  

Science Conference Proceedings (OSTI)

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.

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

2012-04-01T23:59:59.000Z

195

Measurement of W-Boson Polarization in Top-quark Decay using the Full CDF Run II Data Set  

E-Print Network (OSTI)

We measure the polarization of W bosons from top-quark (t) decays into final states with a charged lepton and jets, tt --> WbWb --> lvbqqb, using the full Run II data set collected by the CDF II detector. A model-independent method simultaneously determines the fraction of longitudinal (f_0) and right-handed (f_+) W bosons to yield f_0 = 0.726 +/- 0.066 (stat) +/- 0.067 (syst) and f_+ = -0.045 +/- 0.044 (stat) +/- 0.058 (syst) with a correlation coefficient of -0.69. Additional results are presented under various standard model assumptions. No significant discrepencies with the standard model are observed.

CDF Collaboration

2012-11-19T23:59:59.000Z

196

Measurement of the W boson helicity in top quark decays using 5.4 fb^-1 of ppbar collision data  

E-Print Network (OSTI)

We present a measurement of the helicity of the W boson produced in top quark decays using ttbar 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 ppbar collider. We measure the fractions of longitudinal and right-handed W bosons to be f_0 = 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 f_0 fixed to the value from the standard model yields f_+ = 0.010 +- 0.037 [+- 0.022 (stat.) +- 0.030 (syst.) ].

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

2010-11-30T23:59:59.000Z

197

Quark-antiquark composite systems:the Bethe--Salpeter equation in the spectral-integration technique in the case of the different quark masses  

E-Print Network (OSTI)

The Bethe--Salpeter equations for the quark-antiquark composite systems with different quark masses, such as $q\\bar s$ (with $q=u$,$d$), $q\\bar Q$ and $s \\bar Q$ (with $Q=c$,$b$), are written in terms of spectral integrals. For the mesons characterized by the mass $M$, spin $J$ and radial quantum number $n$, the equations are presented for the $(n,M^2)$-trajectories with fixed $J$. In the spectral-integral technique one can use the energy-dependent forces and get beyond instantaneous approximation. The mixing between states with different quark spin $S$ and angular momentum $L$ are also discussed.

A. V. Anisovich; V. V. Anisovich; V. N. Markov; M. A. Matveev; A. V. Sarantsev

2004-01-28T23:59:59.000Z

198

P-wave contribution to third-order top-quark pair production near threshold  

E-Print Network (OSTI)

The next-to-leading order (NLO) P-wave Coulomb Green function contributes at third-order to top-pair production in e+ e- collisions near threshold. In this paper we compute the NLO P-wave Green function in dimensional regularization, as required for a consistent combination with non-resonant production of the W+ W- b\\bar{b} final state, and present a phenomenological analysis of the P-wave contribution. We further briefly discuss squark production near threshold and top-pair production in gamma gamma collisions, where no S-wave contribution is present, and the P-wave thus constitutes the dominant production process.

M. Beneke; J. Piclum; T. Rauh

2013-12-17T23:59:59.000Z

199

Equation of State for Nucleonic Matter and its Quark Mass Dependence from the Nuclear Force in Lattice QCD  

E-Print Network (OSTI)

Quark mass dependence of the equation of state (EOS) for nucleonic matter is investigated, on the basis of the Brueckner-Hartree-Fock method with the nucleon-nucleon interaction extracted from lattice QCD simulations. We observe saturation of nuclear matter at the lightest available quark mass corresponding to the pseudoscalar meson mass ~ 469 MeV. Mass-radius relation of the neutron stars is also studied with the EOS for neutron-star matter from the same nuclear force in lattice QCD. We observe that the EOS becomes stiffer and thus the maximum mass of neutron star increases as the quark mass decreases toward the physical point.

Takashi Inoue; Sinya Aoki; Takumi Doi; Tetsuo Hatsuda; Yoichi Ikeda; Noriyoshi Ishii; Keiko Murano; Hidekatsu Nemura; Kenji Sasaki

2013-07-01T23:59:59.000Z

200

Thermodynamics with density and temperature dependent particle masses and properties of bulk strange quark matter and strangelets  

E-Print Network (OSTI)

Thermodynamic formulas for investigating systems with density and/or temperature dependent particle masses are generally derived from the fundamental derivation equality of thermodynamics. Various problems in the previous treatments are discussed and modified. Properties of strange quark matter in bulk and strangelets at both zero and finite temperature are then calculated based on the new thermodynamic formulas with a new quark mass scaling, which indicates that low mass strangelets near beta equilibrium are multi-quark states with an anti-strange quark, such as the pentaquark (u^2d^2\\bar{s}) for baryon nmber 1 and the octaquark (u^4d^3\\bar{s}) for dibaryon etc.

X. J. Wen; X. H. Zhong; G. X. Peng; P. N. Shen; P. Z. Ning

2005-06-06T23:59:59.000Z

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201

Top Physics Results from CDF  

E-Print Network (OSTI)

The top quark is by far the most massive fundamental particle observed so far, and the study of its properties is interesting for several reasons ranging from its possible special role in electroweak symmetry breaking to its sensitivity to physics beyond the Standard Model. We present recent top physics results from CDF based on 160-320 inverse pb of ppbar collision data at a center-of-mass energy of 1.96 TeV. The ttbar cross section and the top mass have been measured in different decay channels and using different methods. We have searched for evidence of single top production, setting upper limits on its production rate. Other results shown in this conference include studies of the polarization of W bosons from top decays, a search for charged Higgs decaying from top, and a search for additional heavy t' quarks.

Gervasio Gomez

2005-05-30T23:59:59.000Z

202

Heavy-Quark Free Energy, Debye Mass, and Spatial String Tension at Finite Temperature in Two Flavor Lattice QCD with Wilson Quark Action  

E-Print Network (OSTI)

We study Polyakov loop correlations and spatial Wilson loop at finite Temperature in two-flavor QCD simulations with the RG-improved gluon action and the clover-improved Wilson quark action on a $ 16^3 \\times 4$ lattice. From the line of constant physics at $m_{\\rm PS}/m_{\\rm V}=0.65$ and 0.80, we extract the heavy-quark free energies, the effective running coupling $g_{\\rm eff}(T)$ and the Debye screening mass $m_D(T)$ for various color channels of heavy quark--quark and quark--anti-quark pairs above the critical temperature. The free energies are well approximated by the screened Coulomb form with the appropriate Casimir factors at high temperature. The magnitude and the temperature dependence of the Debye mass are compared to those of the next-to-leading order thermal perturbation theory and to a phenomenological formula in terms of $g_{\\rm eff}(T)$. We make a comparison between our results with the Wilson quark action and the previous results with the staggered quark action. The spatial string tension is also studied in the high temperature phase and is compared to the next-to-next-leading order prediction in an effective theory with dimensional reduction.

WHOT-QCD Collaboration; :; Y. Maezawa; N. Ukita; S. Aoki; S. Ejiri; T. Hatsuda; N. Ishii; K. Kanaya

2007-02-02T23:59:59.000Z

203

Higgs boson mass bounds in the presence of a heavy fourth quark family  

E-Print Network (OSTI)

We present Higgs boson mass bounds in a lattice regularization allowing thus for non-perturbative investigations. In particular, we employ a lattice modified chiral invariant Higgs-Yukawa model using the overlap operator. We show results for the upper and lower Higgs boson mass bounds in the presence of a heavy mass-degenerate quark doublet with masses ranging up to 700 GeV. We perform infinite volume extrapolations in most cases, and examine several values of the lattice cutoff. Furthermore, we argue that the lower Higgs boson mass bound is stable with respect to the addition of higher dimensional operators to the scalar field potential. Our results have severe consequences for the phenomenology of a fourth generation of quarks if a light Higgs boson is discovered at the LHC.

John Bulava; Philipp Gerhold; Karl Jansen; Jim Kallarackal; Attila Nagy

2013-01-16T23:59:59.000Z

204

Glossary Item - Quark  

NLE Websites -- All DOE Office Websites (Extended Search)

family consists of Top and Bottom quarks and only exist at very high energies. The Top quark was finally discovered in 1995 at the Fermi National Accelerator Laboratory. Particle...

205

QCD thermodynamics with $N_f=2+1$ near the continuum limit at realistic quark masses  

E-Print Network (OSTI)

We report on our study of QCD thermodynamics with 2+1 flavors of dynamical quarks. In this proceeding we present several thermodynamic quantities and our recent calculation of the critical temperature. In order to investigate the thermodynamic properties of QCD near the continuum limit we adopt improved staggered (p4) quarks coupled with tree-level Symanzik improved glue on $N_t=4$ and 6 lattices. The simulations are performed with a physical value of the strange quark mass and light quark masses which are in the range of $m_q/m_s=0.05-0.4$. The lightest quark mass corresponds to a pion mass of about 150 MeV.

Takashi Umeda

2006-10-03T23:59:59.000Z

206

Quark-mass dependence of the three-flavor QCD phase diagram at zero and imaginary chemical potential: Model prediction  

Science Conference Proceedings (OSTI)

We draw the three-flavor phase diagram as a function of light- and strange-quark masses for both zero and imaginary quark-number chemical potential, using the Polyakov-loop extended Nambu-Jona-Lasinio model with an effective four-quark vertex depending on the Polyakov loop. The model prediction is qualitatively consistent with 2+1 flavor lattice QCD prediction at zero chemical potential and with degenerate three-flavor lattice QCD prediction at imaginary chemical potential.

Sasaki, Takahiro; Sakai, Yuji; Yahiro, Masanobu [Department of Physics, Graduate School of Sciences, Kyushu University, Fukuoka 812-8581 (Japan); Kouno, Hiroaki [Department of Physics, Saga University, Saga 840-8502 (Japan)

2011-11-01T23:59:59.000Z

207

Dependence of hadronic properties on Quark Masses and Constraints on their Cosmological Variation  

E-Print Network (OSTI)

We follow our previous paper on possible cosmological variation of weak scale (quark masses) and strong scale, inspired by data on cosmological variation of the electromagnetic fine structure constant from distant quasar (QSO) absorption spectra. In this work we identify the {\\em strange quark mass} $m_s$ as the most important quantity, and the {\\em sigma meson mass} as the ingredient of the nuclear forces most sensitive to it. As a result, we claim significantly stronger limits on ratio of weak/strong scale ($W=m_s/\\Lambda_{QCD}$) variation following from our previous discussion of primordial Big-Bang Nucleosynthesis ($|\\delta W/W|nuclear reactor ($|\\delta W/W|<1.2 \\cdot 10^{-10}$; there is also a non-zero solution $\\delta W/W=(-0.56 \\pm 0.05) \\cdot 10^{-9}$) .

V. V. Flambaum; E. V. Shuryak

2002-12-31T23:59:59.000Z

208

Top decay physics at CDF and measurement of the CKM element V{sub tb}  

SciTech Connect

Now that the top quark`s existence has been firmly established by the CDF and D0 experiments{sup 1,2)}, we begin to measure its properties. Branching fractions are of particular interest in the case of the t quark, since they probe the couplings of the top quark to gauge bosons and other quarks, and because ``the top quark is the only quark with reasonable mass``{sup 3)}. Because the top quark is the only quark with mass comparable to the electroweak scale, its decays, particularly non-standard decays, might shed some light on what makes the top quark different from lighter quarks, and the role it plays in electroweak symmetry breaking. This paper describes some recent measurements on the decay of the top quark using the CDF detector, a general purpose detector designed to study p{bar p} collisions at {radical}s=1.8 TeV; it has been described in detail elsewhere{sup 4,1)}. The analyses presented use 100-110 pb{minus}{sup 1} of data collected between 1992 and 1995 at the Fermilab TeVatron.

LeCompte, T.J.

1995-12-31T23:59:59.000Z

209

Search for electroweak single top quark production with cdf in proton - anti-proton collisions at s**(1/2) = 1.96-TeV  

Science Conference Proceedings (OSTI)

In this thesis two searches for electroweak single top quark production with the CDF experiment have been presented, a cutbased search and an iterated discriminant analysis. Both searches find no significant evidence for electroweak single top production using a data set corresponding to an integrated luminosity of 162 pb{sup -1} collected with CDF. Therefore limits on s- and t-channel single top production are determined using a likelihood technique. For the cutbased search a likelihood function based on lepton charge times pseudorapidity of the non-bottom jet was used if exactly one bottom jet was identified in the event. In case of two identified bottom jets a likelihood function based on the total number of observed events was used. The systematic uncertainties have been treated in a Bayesian approach, all sources of systematic uncertainties have been integrated out. An improved signal modeling using the MadEvent Monte Carlo program matched to NLO calculations has been used. The obtained limits for the s- and t-channel single top production cross sections are 13.6 pb and 10.1 pb, respectively. To date, these are most stringent limits published for the s- and the t-channel single top quark production modes.

Walter, Thorsten; /Karlsruhe U., EKP

2005-06-01T23:59:59.000Z

210

Finite volume effects and quark mass dependence of the N(1535) and N(1650)  

E-Print Network (OSTI)

For resonances decaying in a finite volume, the simple identification of state and eigenvalue is lost. The extraction of the scattering amplitude is a major challenge as we demonstrate by extrapolating the physical S_{11} amplitude of pion-nucleon scattering to the finite volume and unphysical quark masses, using a unitarized chiral framework including all next-to-leading order contact terms. We show that the pole movement of the resonances N(1535)1/2^- and N(1650)1/2^- with varying quark masses is non-trivial. In addition, there are several strongly coupled S-wave thresholds that induce a similar avoided level crossing as narrow resonances. The level spectrum is predicted for two typical lattice setups, and ways to extract the amplitude from upcoming lattice data are discussed.

Michael Döring; Maxim Mai; Ulf-G. Meißner

2013-02-17T23:59:59.000Z

211

Higgs boson mass bounds in the presence of a very heavy fourth quark generation  

E-Print Network (OSTI)

We study the effect of a potential fourth quark generation on the upper and lower Higgs boson mass bounds. This investigation is based on the numerical evaluation of a chirally invariant lattice Higgs-Yukawa model emulating the same Higgs-fermion coupling structure as in the Higgs sector of the electroweak Standard Model. In particular, the considered model obeys a Ginsparg-Wilson version of the underlying ${SU}(2)_L\\times {U}(1)_Y$ symmetry, being a global symmetry here due to the neglection of gauge fields in this model. We present our results on the modification of the upper and lower Higgs boson mass bounds induced by the presence of a hypothetical very heavy fourth quark doublet. Finally, we compare these findings to the standard scenario of three fermion generations.

P. Gerhold; K. Jansen; J. Kallarackal

2010-11-07T23:59:59.000Z

212

Quark-gluon vertex dressing and meson masses beyond ladder-rainbow truncation  

Science Conference Proceedings (OSTI)

We include a generalized infinite class of quark-gluon vertex dressing diagrams in a study of how dynamics beyond the ladder-rainbow truncation influences the Bethe-Salpeter description of light-quark pseudoscalar and vector mesons. The diagrammatic specification of the vertex is mapped into a corresponding specification of the Bethe-Salpeter kernel, which preserves chiral symmetry. This study adopts the algebraic format afforded by the simple interaction kernel used in previous work on this topic. The new feature of the present work is that in every diagram summed for the vertex and the corresponding Bethe-Salpeter kernel, each quark-gluon vertex is required to be the self-consistent vertex solution. We also adopt from previous work the effective accounting for the role of the explicitly non-Abelian three-gluon coupling in a global manner through one parameter determined from recent lattice-QCD data for the vertex. Within the current model, the more consistent dressed vertex limits the ladder-rainbow truncation error for vector mesons to be never more than 10% as the current quark mass is varied from the u/d region to the b region.

Matevosyan, Hrayr H. [Louisiana State University, Department of Physics and Astronomy, 202 Nicholson Hall, Tower Dr., Louisiana 70803 (United States); Thomas Jefferson National Accelerator Facility, 12000 Jefferson Ave., Newport News, Virginia 23606 (United States); Laboratory of Theoretical Physics, JINR, Dubna (Russian Federation); Thomas, Anthony W. [Thomas Jefferson National Accelerator Facility, 12000 Jefferson Ave., Newport News, Virginia 23606 (United States); Tandy, Peter C. [Center for Nuclear Research, Department of Physics, Kent State University, Kent, Ohio 44242 (United States)

2007-04-15T23:59:59.000Z

213

Enhancing the Sensitivity to New Physics in the top-antitop Invariant Mass Distribution  

Science Conference Proceedings (OSTI)

We propose selection cuts on the LHC t{bar t} production sample which should enhance the sensitivity to New Physics signals in the study of the t{bar t} invariant mass distribution. We show that selecting events in which the t{bar t} object has little transverse and large longitudinal momentum enlarges the quark-fusion fraction of the sample and therefore increases its sensitivity to New Physics which couples to quarks and not to gluons. We find that systematic error bars play a fundamental role and assume a simple model for them. We check how a non-visible new particle would become visible after the selection cuts enhance its resonance bump. A final realistic analysis should be done by the experimental groups with a correct evaluation of the systematic error bars.

Alvarez, Ezequiel; /Univ. Nacional San Luis /SLAC

2012-06-14T23:59:59.000Z

214

Sensitivity to the Single Production of Vector-Like Quarks at an Upgraded Large Hadron Collider  

E-Print Network (OSTI)

In this note we consider the sensitivity of the Large Hadron Collider (LHC) to the single production of new heavy vector-like quarks. We consider a model with large mixing with the standard model top quark with electroweak production of single heavy top quarks. We consider center of mass energies of 14, 33, and 100 TeV with various pileup scenarios and present the expected sensitivity and exclusion limits.

Tim Andeen; Clare Bernard; Kevin Black; Taylor Childres; Lidia Dell'Asta; Natascia Vignaroli

2013-09-07T23:59:59.000Z

215

Quark Matter  

NLE Websites -- All DOE Office Websites (Extended Search)

Quark Quark Matter in Neutron Stars Prashanth Jaikumar Argonne National Laboratory, (PHY) September 7th, 2006 . - p.1/29 Outline * Neutron stars: observations by a theorist . - p.2/29 Outline * Neutron stars: observations by a theorist * Mass-Radius constraints on Equation of State (EoS) . - p.2/29 Outline * Neutron stars: observations by a theorist * Mass-Radius constraints on Equation of State (EoS) * Is quark matter inside neutron stars ruled out? . - p.2/29 Outline * Neutron stars: observations by a theorist * Mass-Radius constraints on Equation of State (EoS) * Is quark matter inside neutron stars ruled out? ------------------------ * Strange Quark stars: Features and "Findings" . - p.2/29 Outline * Neutron stars: observations by a theorist * Mass-Radius constraints on Equation of State (EoS) * Is quark matter inside neutron stars ruled out? ------------------------

216

Ginzburg-Landau phase diagram for dense matter with axial anomaly, strange quark mass, and meson condensation  

SciTech Connect

We discuss the phase structure of dense matter, in particular, the nature of the transition between hadronic and quark matter. Calculations within a Ginzburg-Landau approach show that the axial anomaly can induce a critical point in this transition region. This is possible because in three-flavor quark matter with instanton effects a chiral condensate can be added to the color-flavor locked phase without changing the symmetries of the ground state. In (massless) two-flavor quark matter such a critical point is not possible since the corresponding color superconductor (2SC) does not break chiral symmetry. We study the effects of a nonzero but finite strange quark mass which interpolates between these two cases. Since at ultrahigh density the first reaction of the color-flavor locked phase to a nonzero strange quark mass is to develop a kaon condensate, we extend previous Ginzburg-Landau studies by including such a condensate. We discuss the fate of the critical point systematically and show that the continuity between hadronic and quark matter can be disrupted by the onset of a kaon condensate. Moreover, we identify the mass terms in the Ginzburg-Landau potential which are needed for the 2SC phase to occur in the phase diagram.

Schmitt, Andreas; Stetina, Stephan [Institut fuer Theoretische Physik, Technische Universitaet Wien, 1040 Vienna (Austria); Tachibana, Motoi [Department of Physics, Saga University, Saga 840-8502 (Japan)

2011-02-15T23:59:59.000Z

217

Search for the single top quarks produced in s-channel via electroweak interactions at s = 1-96 at the Tevatron  

SciTech Connect

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.

Jabeen, Shabnam; /Kansas U.

2006-01-01T23:59:59.000Z

218

CP violating anomalous top-quark coupling in p$\\bar{p}$ collision at $\\sqrt{s}=1.96$ TeV  

SciTech Connect

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.

Lee, Sehwook; /Iowa State U.

2011-04-01T23:59:59.000Z

219

Two-loop soft anomalous dimensions for single top quark associated production with a W{sup -} or H{sup -}  

SciTech Connect

I present results for the two-loop soft anomalous dimensions for associated production of a single top quark with a W boson or a charged Higgs boson. The calculation uses expressions for the massive cusp anomalous dimension, which are presented in different forms, and it allows soft-gluon resummation at next-to-next-to-leading-logarithm (NNLL) accuracy. From the NNLL resummed cross section I derive approximate NNLO cross sections for bg{yields}tW{sup -} and bg{yields}tH{sup -} at LHC energies of 7, 10, and 14 TeV.

Kidonakis, Nikolaos [Kennesaw State University, Physics no. 1202, 1000 Chastain Road, Kennesaw, Georgia 30144-5591 (United States)

2010-09-01T23:59:59.000Z

220

Search for the pair production of scalar top quarks in the acoplanar charm jet final state in p anti-p collisions at s**(1/2) = 1.96-TeV  

SciTech Connect

A search for the pair production of scalar top quarks, {bar t}, has been performed in 360 pb{sup -1} of data from p{bar p} collisions at a center-of-mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron collider. The {bar t} decay mode considered is {bar t} {yields} c{bar {chi}}{sub 1}{sup 0}, where {bar {chi}}{sub 1}{sup 0} is the lightest supersymmetric particle. The topology analyzed therefore consists of a pair of acoplanar heavy-flavor jets with missing transverse energy. The data show good agreement with the standard model expectation, and a 95% C.L. exclusion domain in the (m{sub {tilde t}}, m{sub {tilde {chi}}{sub 1}{sup 0}}) plane has been determined, extending the domain excluded by previous experiments.

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.; /Buenos Aires U. /Rio de Janeiro, CBPF /Rio de Janeiro State U. /Sao Paulo, IFT /Alberta U. /Simon Fraser U. /York U., Canada /McGill U. /Hefei, CUST /Andes U., Bogota /Charles U.

2006-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "top quark mass" from the National Library of EnergyBeta (NLEBeta).
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221

Towards thermodynamics with $N_f=2+1+1$ twisted mass quarks  

E-Print Network (OSTI)

We present preliminary results achieved within a recently started project dealing with QCD thermodynamics in the presence of a fully dynamical second quark family. We are employing the Wilson twisted mass discretization. To reduce the amount of zero temperature simulations and the cost of analysis we have chosen the fixed-scale approach. We show a variety of basic thermodynamic observables for temperatures ranging from 158 to 633 MeV. Simulations were performed for three lattice spacings below 0.1 fm each and at a single value of the pion mass which allows a comparison with previously obtained $N_f=2$ results. We determine the chiral crossover temperature from the bare chiral susceptibility and show results for the gauge part of the trace anomaly.

Florian Burger; Grit Hotzel; Michael Müller-Preussker; Ernst-Michael Ilgenfritz; Maria Paola Lombardo

2013-11-07T23:59:59.000Z

222

Top differential cross section measurements (Tevatron)  

SciTech Connect

Differential cross sections in the top quark sector measured at the Fermilab Tevatron collider are presented. CDF used 2.7 fb{sup -1} of data and measured the differential cross section as a function of the invariant mass of the t{bar t} system. The measurement shows good agreement with the standard model and furthermore is used to derive limits on the ratio {kappa}/M{sub Pl} for gravitons which decay to top quarks in the Randall-Sundrum model. D0 used 1.0 fb{sup -1} of data to measure the differential cross section as a function of the transverse momentum of the top-quark. The measurement shows a good agreement to the next-to-leading order perturbative QCD prediction and various other standard model predictions.

Jung, Andreas W.

2012-01-01T23:59:59.000Z

223

Tevatron-for-LHC Report: Top and Electroweak Physics  

E-Print Network (OSTI)

The top quark and electroweak bosons (W and Z) represent the most massive fundamental particles yet discovered, and as such refer directly to the Standard Model's greatest remaining mystery: the mechanism by which all particles gained mass. This report summarizes the work done within the top-ew group of the Tevatron-for-LHC workshop. It represents a collection of both Tevatron results, and LHC predictions. The hope is that by considering and comparing both machines, the LHC program can be improved and aided by knowledge from the Tevatron, and that particle physics as a whole can be enriched. The report includes measurements of the top quark mass, searches for single top quark production, and physics of the electroweak bosons at hadron colliders.

C. E. Gerber; P. Murat; T. M. P. Tait; D. Wackeroth; A. Arbuzov; D. Bardin; U. Baur; J. A. Benitez; S. Berge; S. Bondarenko; E. E. Boos; M. T. Bowen; R. Brock; V. E. Bunichev; J. Campbell; F. Canelli; Q. -H. Cao; C. M. Carloni Calame; F. Chevallier; P. Christova; C. Ciobanu; S. Dittmaier; L. V. Dudko; S. D. Ellis; A. I. Etienvre; F. Fiedler; A. Garcia-Bellido; A. Giammanco; D. Glenzinski; P. Golonka; C. Hays; S. Jadach; S. Jain; L. Kalinovskaya; M. Kramer; A. Lleres; J. Luck; A. Lucotte; A. Markina; G. Montagna; P. M. Nadolsky; O. Nicrosini; F. I. Olness; W. Placzek; R. Sadykov; V. I. Savrin; R. Schwienhorst; A. V. Sherstnev; S. Slabospitsky; B. Stelzer; M. J. Strassler; Z. Sullivan; F. Tramontano; A. Vicini; W. Wagner; Z. Was; G. Watts; M. Weber; S. Willenbrock; U. K. Yang; C-P. Yuan; J. Zhu

2007-05-22T23:59:59.000Z

224

Search for a Very Light CP-Odd Higgs Boson in Top Quark Decays from pp[over-bar] Collisions at [sqrt]s=1.96??TeV  

E-Print Network (OSTI)

We present the results of a search for a very light CP-odd Higgs boson a10 originating from top quark decays t-->H±b-->W±[superscript (*)]a10b, and subsequently decaying into tau+tau-. Using a data sample corresponding to ...

Bauer, Gerry P.

225

Determination of W boson helicity fractions in top quark decays in p anti-p collisions at CDF Run II and production of endcap modules for the ATLAS Silicon Tracker  

SciTech Connect

The thesis presented here includes two parts. The first part discusses the production of endcap modules for the ATLAS SemiConductor Tracker at the University of Geneva. The ATLAS experiment is one of the two multi-purpose experiments being built at the LHC at CERN. The University of Geneva invested extensive efforts to create an excellent and efficient module production site, in which 655 endcap outer modules were constructed. The complexity and extreme requirements for 10 years of LHC operation with a high resolution, high efficiency, low noise tracking system resulted in an extremely careful, time consuming production and quality assurance of every single module. At design luminosity about 1000 particles will pass through the tracking system each 25 ns. In addition to requiring fast tracking techniques, the high particle flux causes significant radiation damage. Therefore, modules have to be constructed within tight and accurate mechanical and electrical specification. A description of the ATLAS experiment and the ATLAS Semiconductor tracker is presented, followed by a detailed overview of the module production at the University of Geneva. My personal contribution to the endcap module production at the University of Geneva was taking part, together with other physicists, in selecting components to be assembled to a module, including hybrid reception tests, measuring the I-V curve of the sensors and the modules at different stages of the production, thermal cycling the modules and performing electrical readout tests as an initial quality assurance of the modules before they were shipped to CERN. An elaborated description of all of these activities is given in this thesis. At the beginning of the production period the author developed a statistics package which enabled us to monitor the rate and quality of the module production. This package was then used widely by the ATLAS SCT institutes that built endcap modules of any type, and kept being improved and updated. The production monitoring and summary using this package is shown in this thesis. The second part of the thesis reports a measurement of the fraction of longitudinal and right-handed helicity states of W bosons in top quark decays. This measurement was done using 955 pb{sup -1} of data collected with the CDF detector at the TEvatron, where protons and anti-protons are collided with a center-of-mass energy of 1.96 TeV. the helicity fraction measurements take advantage of the fact that the angular distribution of the W boson decay products depends on the helicity state of the W which they originate from. They analyze t{bar t} events in the 'lepton+jets' channel and look at the leptonic side of decay. They construct templates for the distribution of cos{theta}*, the angle between the charged lepton and the W flight direction in the rest frame of the top quark. Using Monte Carlo techniques, they construct probability distributions ('templates') for cos{theta}* in the case of left-handed, longitudinal and right-handed Ws and a template for the background model. They extract the W helicity fractions using an unbinned likelihood fitter based on the information of these templates. The Standard Model predicts the W helicity fractions to be about 70% longitudinal and 30% left-handed, while the fraction of right-handed W bosons in top decays is highly suppressed and vanishes when neglecting the mass of the b quark.

Moed, Shulamit; /Geneva U.

2007-01-01T23:59:59.000Z

226

Limits on Cosmological Variation of Strong Interaction and Quark Masses from Big Bang Nucleosynthesis, Cosmic, Laboratory and Oklo Data  

E-Print Network (OSTI)

Recent data on cosmological variation of the electromagnetic fine structure constant from distant quasar (QSO) absorption spectra have inspired a more general discussion of possible variation of other constants. We discuss variation of strong scale and quark masses. We derive the limits on their relative change from (i) primordial Big-Bang Nucleosynthesis (BBN); (ii) Oklo natural nuclear reactor, (iii) quasar absorption spectra, and (iv) laboratory measurements of hyperfine intervals.

V. V. Flambaum; E. V. Shuryak

2002-01-31T23:59:59.000Z

227

Top Physics at the LHC  

E-Print Network (OSTI)

Top quark physics will be a prominent topic in Standard Model physics at the LHC. The enormous amount of top quarks expected to be produced will allow to perform a wide range of precision measurements. An overview of the planned top physics programme of the ATLAS and CMS experiments at the LHC is given.

Christian Weiser

2005-06-10T23:59:59.000Z

228

Enhanced effect of quark mass variation in 229Th and limits from Oklo data  

E-Print Network (OSTI)

The effects of the variation of the dimensionless strong interaction parameter Xq=mq/Lambda{QCD} (mq is the quark mass, Lambda{QCD} is the QCD scale) are enhanced about 1.5 x 10**5 times in the 7.6 eV "nuclear clock" transition between the ground and first excited states in the 229Th nucleus and about 1 x 10**8 times in the relative shift of the 0.1 eV compound resonance in 150Sm.The best terrestrial limit on the temporal variation of the fundamental constants, |delta(Xq)/Xq| nuclear reactor data. The results for 229Th and 150Sm are obtained by extrapolation from light nuclei where the many-body calculations can be performed more accurately. The errors produced by such extrapolation may be smaller than the errors of direct calculations in heavy nuclei. The extrapolation results are compared with the "direct" estimates obtained using the Walecka model. A number of numerical relations needed for the calculations of the variation effects in nuclear physics and atomic spectroscopy have been obtained: for the nuclear binding energy delta(E)/E ~ -1.45 delta(mq)/mq, for the spin-orbit intervals delta(Eso)/Eso ~ -0.22 delta(mq)/mq, for the nuclear radius delta(r)/r ~ 0.3 delta(mq)/mq (in units of Lambda{QCD}); for the shifts of nuclear resonances and weakly bound energy levels delta(Er) ~ 10 delta(Xq)/Xq MeV.

V. V. Flambaum; R. B. Wiringa

2008-07-30T23:59:59.000Z

229

Higgs boson discovery through top-partners decays using jet substructure  

SciTech Connect

Top partners--vectorlike quarks which mix predominantly with the top quark, are simple extensions of the standard model present in many theories of new physics such as little Higgs models, topcolor models, and extra dimensions. Through renormalizable mixing with the top quark, these top partners inherit couplings to the Higgs boson. Higgs bosons produced from the decay of top partners are often highly boosted and ideal candidates for analyses based on jet substructure. Using substructure methods, we show that light Higgs bosons decaying to bb can be discovered at the 14 TeV LHC with less than 10 fb{sup -1} for top-partner masses up to 1 TeV.

Kribs, Graham D. [Theoretical Physics Department, Fermilab, Batavia, Illinois 60510 (United States); Department of Physics, University of Oregon, Eugene, Oregon 97403 (United States); Martin, Adam [Theoretical Physics Department, Fermilab, Batavia, Illinois 60510 (United States); Roy, Tuhin S. [Department of Physics, University of Washington, Seattle, Washington 98195 (United States)

2011-11-01T23:59:59.000Z

230

Measurement of the Differential Cross Section d?/d(cos ?t) for Top-Quark Pair Production in p-pbar Collisions at sqrt{s} = 1.96 TeV  

E-Print Network (OSTI)

We report a measurement of the differential cross section, d{\\sigma}/d(cos {\\theta}t), for top-quark-pair production as a function of the top-quark production angle in proton-antiproton collisions at sqrt{s} = 1.96 TeV. This measurement is performed using data collected with the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.4/fb. We employ the Legendre polynomials to characterize the shape of the differential cross section at the parton level. The observed Legendre coefficients are in good agreement with the prediction of the next-to-leading-order standard-model calculation, with the exception of an excess linear-term coefficient, a1 = 0.40 +- 0.12, compared to the standard-model prediction of a1 = 0.15^{+0.07}_{-0.03}.

CDF Collaboration; T. Aaltonen; S. Amerio; D. Amidei; A. Anastassov; A. Annovi; J. Antos; G. Apollinari; J. A. Appel; T. Arisawa; A. Artikov; J. Asaadi; W. Ashmanskas; B. Auerbach; A. Aurisano; F. Azfar; W. Badgett; T. Bae; A. Barbaro-Galtieri; V. E. Barnes; B. A. Barnett; P. Barria; P. Bartos; M. Bauce; F. Bedeschi; S. Behari; G. Bellettini; J. Bellinger; D. Benjamin; A. Beretvas; A. Bhatti; K. R. Bland; B. Blumenfeld; A. Bocci; A. Bodek; D. Bortoletto; J. Boudreau; A. Boveia; L. Brigliadori; C. Bromberg; E. Brucken; J. Budagov; H. S. Budd; K. Burkett; G. Busetto; P. Bussey; P. Butti; A. Buzatu; A. Calamba; S. Camarda; M. Campanelli; F. Canelli; B. Carls; D. Carlsmith; R. Carosi; S. Carrillo; B. Casal; M. Casarsa; A. Castro; P. Catastini; D. Cauz; V. Cavaliere; M. Cavalli-Sforza; A. Cerri; L. Cerrito; Y. C. Chen; M. Chertok; G. Chiarelli; G. Chlachidze; K. Cho; D. Chokheli; A. Clark; C. Clarke; M. E. Convery; J. Conway; M. Corbo; M. Cordelli; C. A. Cox; D. J. Cox; M. Cremonesi; D. Cruz; J. Cuevas; R. Culbertson; N. d'Ascenzo; M. Datta; P. de Barbaro; L. Demortier; M. Deninno; M. D'Errico; F. Devoto; A. Di Canto; B. Di Ruzza; J. R. Dittmann; S. Donati; M. D'Onofrio; M. Dorigo; A. Driutti; K. Ebina; R. Edgar; A. Elagin; R. Erbacher; S. Errede; B. Esham; S. Farrington; J. P. Fernández Ramos; R. Field; G. Flanagan; R. Forrest; M. Franklin; J. C. Freeman; H. Frisch; Y. Funakoshi; C. Galloni; A. F. Garfinkel; P. Garosi; H. Gerberich; E. Gerchtein; S. Giagu; V. Giakoumopoulou; K. Gibson; C. M. Ginsburg; N. Giokaris; P. Giromini; G. Giurgiu; V. Glagolev; D. Glenzinski; M. Gold; D. Goldin; A. Golossanov; G. Gomez; G. Gomez-Ceballos; M. Goncharov; O. González López; I. Gorelov; A. T. Goshaw; K. Goulianos; E. Gramellini; S. Grinstein; C. Grosso-Pilcher; R. C. Group; J. Guimaraes da Costa; S. R. Hahn; J. Y. Han; F. Happacher; K. Hara; M. Hare; R. F. Harr; T. Harrington-Taber; K. Hatakeyama; C. Hays; J. Heinrich; M. Herndon; A. Hocker; Z. Hong; W. Hopkins; S. Hou; R. E. Hughes; U. Husemann; M. Hussein; J. Huston; G. Introzzi; M. Iori; A. Ivanov; E. James; D. Jang; B. Jayatilaka; E. J. Jeon; S. Jindariani; M. Jones; K. K. Joo; S. Y. Jun; T. R. Junk; M. Kambeitz; T. Kamon; P. E. Karchin; A. Kasmi; Y. Kato; W. Ketchum; J. Keung; B. Kilminster; D. H. Kim; H. S. Kim; J. E. Kim; M. J. Kim; S. H. Kim; S. B. Kim; Y. J. Kim; Y. K. Kim; N. Kimura; M. Kirby; K. Knoepfel; K. Kondo; D. J. Kong; J. Konigsberg; A. V. Kotwal; M. Kreps; J. Kroll; M. Kruse; T. Kuhr; M. Kurata; A. T. Laasanen; S. Lammel; M. Lancaster; K. Lannon; G. Latino; H. S. Lee; J. S. Lee; S. Leo; S. Leone; J. D. Lewis; A. Limosani; E. Lipeles; A. Lister; H. Liu; Q. Liu; T. Liu; S. Lockwitz; A. Loginov; D. Lucchesi; A. Lucà; J. Lueck; P. Lujan; P. Lukens; G. Lungu; J. Lys; R. Lysak; R. Madrak; P. Maestro; S. Malik; G. Manca; A. Manousakis-Katsikakis; L. Marchese; F. Margaroli; P. Marino; M. Martínez; K. Matera; M. E. Mattson; A. Mazzacane; P. Mazzanti; R. McNulty; A. Mehta; P. Mehtala; C. Mesropian; T. Miao; D. Mietlicki; A. Mitra; H. Miyake; S. Moed; N. Moggi; C. S. Moon; R. Moore; M. J. Morello; A. Mukherjee; Th. Muller; P. Murat; M. Mussini; J. Nachtman; Y. Nagai; J. Naganoma; I. Nakano; A. Napier; J. Nett; C. Neu; T. Nigmanov; L. Nodulman; S. Y. Noh; O. Norniella; L. Oakes; S. H. Oh; Y. D. Oh; I. Oksuzian; T. Okusawa; R. Orava; L. Ortolan; C. Pagliarone; E. Palencia; P. Palni; V. Papadimitriou; W. Parker; G. Pauletta; M. Paulini; C. Paus; T. J. Phillips; G. Piacentino; E. Pianori; J. Pilot; K. Pitts; C. Plager; L. Pondrom; S. Poprocki; K. Potamianos; A. Pranko; F. Prokoshin; F. Ptohos; G. Punzi; N. Ranjan; I. Redondo Fernández; P. Renton; M. Rescigno; F. Rimondi; L. Ristori; A. Robson; T. Rodriguez; S. Rolli; M. Ronzani; R. Roser; J. L. Rosner; F. Ruffini; A. Ruiz; J. Russ; V. Rusu; W. K. Sakumoto; Y. Sakurai; L. Santi; K. Sato; V. Saveliev; A. Savoy-Navarro; P. Schlabach; E. E. Schmidt; T. Schwarz; L. Scodellaro; F. Scuri; S. Seidel; Y. Seiya; A. Semenov; F. Sforza; S. Z. Shalhout; T. Shears; P. F. Shepard; M. Shimojima; M. Shochet; I. Shreyber-Tecker; A. Simonenko; K. Sliwa; J. R. Smith; F. D. Snider; H. Song; V. Sorin; R. St. Denis; M. Stancari; D. Stentz; J. Strologas; Y. Sudo; A. Sukhanov; I. Suslov; K. Takemasa; Y. Takeuchi; J. Tang; M. Tecchio; P. K. Teng; J. Thom; E. Thomson; V. Thukral; D. Toback; S. Tokar; K. Tollefson; T. Tomura; D. Tonelli; S. Torre; D. Torretta; P. Totaro; M. Trovato; F. Ukegawa; S. Uozumi; G. Velev; C. Vellidis; C. Vernieri; M. Vidal; R. Vilar; J. Vizán; M. Vogel; G. Volpi; F. Vázquez; P. Wagner; R. Wallny; S. M. Wang; D. Waters; W. C. Wester III; D. Whiteson; A. B. Wicklund; S. Wilbur; H. H. Williams; J. S. Wilson; P. Wilson; B. L. Winer; P. Wittich; S. Wolbers; H. Wolfe; T. Wright; X. Wu; Z. Wu; K. Yamamoto; D. Yamato; T. Yang; U. K. Yang; Y. C. Yang; W. -M. Yao; G. P. Yeh; K. Yi; J. Yoh; K. Yorita; T. Yoshida; G. B. Yu

2013-06-10T23:59:59.000Z

231

Search for Single Top Production at the Tevatron  

SciTech Connect

The authors 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. The authors use a data sample corresponding to 0.7 fb{sup -1} recorded by the upgraded Collider Detector at Fermilab (CDFII) and a data sample corresponding to 370 pb{sup -1} recorded by D0. Both CDF and D0 find no significant evidence for electroweak top quark production and set upper limits at the 95% confidence level on the production cross section.

Gresele, Ambra; /INFN, Trento

2006-05-01T23:59:59.000Z

232

Top Polarization in Stop Production at the LHC  

E-Print Network (OSTI)

We survey the expected polarization of the top produced in the decay of a scalar top quark, $\\tilde t \\rightarrow {\\tilde t}\\chi_i^0, i =1-2$. The phenomenology is quite interesting, since the expected polarization depends both on the mixing in the stop and neutralino sectors and on the mass differences between the stop and the neutralino. We find that a mixed stop behaves almost like a right-handed stop due to the larger hypercharge that enters the stop/top/gaugino coupling and that these polarisation effects disappear, when $m_{\\tilde t_1} \\approx m_t+m_{\\tilde\\chi^0_i}$. After a discussion on the expected top polarization from the decay of a scalar top quark, we focus on the interplay of polarization and kinematics at the LHC. We discuss different probes of the top polarization in terms of lab-frame observables. We find that these observables faithfully reflect the polarization of the parent top-quark, but also have a non-trivial dependence on the kinematics of the stop production and decay process. In addition, we illustrate the effect of top polarization on the energy and transverse momentum of the decay lepton in the laboratory frame. Our results show that both spectra are softened substantially in case of a negatively polarized top, particularly for a large mass difference between the stop and the neutralino. Thus, the search strategies, and the conclusions that can be drawn from them, depends not just on the mass difference $m_{\\tilde t} - m_{\\tilde\\chi_{i}^{0}}$ due to the usual kinematic effects but also on the effects of top polarization on the decay kinematics the extent of which depends in turn on the said mass difference.

G. Belanger; R. M. Godbole; L. Hartgring; I. Niessen

2012-12-14T23:59:59.000Z

233

Looking for the Top Quark  

NLE Websites -- All DOE Office Websites (Extended Search)

Graphing is an important tool used by scientists to interpret data. Students can practice their graphing skills while playing this game. Teacher Overview VA State Standards of...

234

Eingeschlossene Quarks  

NLE Websites -- All DOE Office Websites (Extended Search)

Quarks sind - zusammen mit andern Quarks - immer in Gruppen (Hadronen) gebunden (engl. quark confinement). Diese zusammengesetzten Zustnde sind farbneutral. Im Verlauf der...

235

Cold quark matter in compact stars  

Science Conference Proceedings (OSTI)

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.

Franzon, B.; Fogaca, D. A.; Navarra, F. S. [Instituto de Fisica, Universidade de Sao Paulo Rua do Matao, Travessa R, 187, 05508-090 Sao Paulo, SP (Brazil); Horvath, J. E. [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao, 1226, 05508-090, Sao Paulo, SP (Brazil)

2013-03-25T23:59:59.000Z

236

Search for New Physics in Single Top Channel at the LHC  

E-Print Network (OSTI)

At the seventh International Workshop on the CKM Unitarity Triangle, a talk on the search for new physics in single top quark production at the LHC experiments was presented. Three analysis were shown: the search for single top quark production through FCNC processes performed by the ATLAS \\cite{Aad:2008zzm}, the search for $W^{'}$ boson by ATLAS using the $tb$ resonance using the invariant mass distribution of the $tb$ system and the search for $W^{'}$ boson done by CMS \\cite{Chatrchyan:2008aa} using boosted decision tree and the invariant mass distribution of the $tb$ system.

Alhroob, Muhammad

2012-01-01T23:59:59.000Z

237

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

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}.

Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U.; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Apresyan, A.; /Purdue U.; Arisawa, T.; /Waseda U. /Dubna, JINR

2011-03-01T23:59:59.000Z

238

Implications of the measurement of pulsars with two solar masses for quark matter in compact stars and HIC. A NJL model case study  

E-Print Network (OSTI)

The precise measurement of the high masses of the pulsars PSR J1614-2230 (M_{1614}=1.97 +- 0.04 solar masses) and PSR J0348-0432 (M_{0348}=2.01 +- 0.04 solar masses) provides an important constraint for the equation of state of cold, dense matter and is suited to give interesting insights regarding the nature and existence of the possible phase transition to deconfined quark matter in the cores of neutron stars. We analyze the stability and composition of compact star sequences for a class of hybrid nuclear - quark-matter equations of state. The quark matter phase is described in the framework of a standard color superconducting 3-flavor Nambu-Jona-Lasinio model and the hadronic phase is given by the Dirac-Brueckner-Hartree-Fock equation of state for the Bonn-A potential. The phase transition is obtained by a Maxwell construction. Within this model setup we aim to constrain otherwise not strictly fixed parameters of the NJL model, namely the coupling strengths in the vector meson and diquark interaction channels. We perform this investigation for two different parameterizations characterized by a different scalar coupling constant. The analysis of flow data obtained in heavy-ion collisions resulted in a further constraint which we account for in our discussion. Massive hybrid stars with extended quark matter cores can be obtained in accordance with all of the considered constraints.

T. Klahn; D. B. Blaschke; R. ?astowiecki

2013-07-26T23:59:59.000Z

239

quarks_q000.dvi  

NLE Websites -- All DOE Office Websites (Extended Search)

- 1- QUARK MASSES Written by A. Manohar (University of California, San Diego). A. Introduction This note discusses some of the theoretical issues involved in the determination of...

240

Top anti-top forward-backward asymmetry in the economical 331 model  

Science Conference Proceedings (OSTI)

Within the economical 331 model the top-antitop asymmetry at the Tevatron where the quark-antiquark annihilation subprocess dominates is calculated. The results are also discussed.

Mekahlia, A.; Mebarki, N.; Haouchine, M. [Laboratoire de Physique Mathematique et Subatomique, Mentouri University, Constantine (Algeria)

2012-06-27T23:59:59.000Z

Note: This page contains sample records for the topic "top quark mass" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

quarks-web.dvi  

NLE Websites -- All DOE Office Websites (Extended Search)

and and 2013 update for the 2014 edition (URL: http://pdg.lbl.gov) December 18, 2013 12:00 - 2- the introduction of a dimensionful scale parameter µ. The mass parameters in the QCD Lagrangian Eq. (1) depend on the renor- malization scheme used to define the theory, and also on the scale parameter µ. The most commonly used renormalization scheme for QCD perturbation theory is the MS scheme. The QCD Lagrangian has a chiral symmetry in the limit that the quark masses vanish. This symmetry is spontaneously broken by dynamical chiral symmetry breaking, and explicitly broken by the quark masses. The nonperturbative scale of dynamical chiral symmetry breaking, Λ χ , is around 1 GeV [2]. It is conventional to call quarks heavy if m > Λ χ , so that explicit chiral symmetry breaking dominates (c, b, and t quarks are heavy), and light if m < Λ χ , so that spontaneous chiral symmetry breaking

242

Status of the DO top search  

Science Conference Proceedings (OSTI)

Preliminary new results on the top quark search with the DO experiment in {bar p}p collisions at {radical}s = 1.8 TeV for an integrated luminosity of 15.2 {plus_minus} 1.8 pb{sup {minus}1} are reported. In this new analysis, which is optimized for high mass top search, a total of seven candidate events in the electron and muon dilepton decay channels (t{bar t} {yields} e{mu}, ee and {mu}{mu}), single lepton decay channels (t{bar t} {yields} e + jets and t{bar t} {yields} {mu} + jets) without b tagging and single electron decay channel (t{bar t} {yields} e + jets) with b tagging have been observed. The estimated background is 4.7 {plus_minus} 1.0 events. If we assume the top quark has a mass of 180 GeV/c{sup 2}, a t{bar t} production cross section of 3.2 {plus_minus} 3.9 pb with upper limit of 13 pb at 95% C.L. is obtained.

Li-Demarteau, Q.; DO Collaboration

1994-09-01T23:59:59.000Z

243

NNLL threshold resummation for top-pair and single-top production  

E-Print Network (OSTI)

I discuss threshold resummation at NNLL accuracy in the standard moment-space approach in perturbative QCD for top-pair and single-top production. For top quark pair production I present new approximate NNLO results for the total cross section and for the top quark transverse momentum and rapidity distributions at 8 TeV LHC energy. I discuss the accuracy of the soft-gluon approximation and show that the NLO and NNLO approximate results from resummation are practically indistinguishable from exact NLO and partial NNLO results. For single top production I present new approximate NNLO results for the total cross sections in all three channels at the LHC and also for the top quark transverse momentum distributions in t-channel production and in top-quark associated production with a W boson. For both ttbar and single-top production the agreement of theoretical results with LHC and Tevatron data is excellent.

Nikolaos Kidonakis

2012-10-29T23:59:59.000Z

244

Single top and Higgs associated production at the LHC.  

SciTech Connect

We study the production of a standard model (SM) Higgs boson in association with a single top quark and either a light jet or W boson at the LHC with a center of mass energy of 14 TeV. Because of the destructive interference of the contributing SM diagrams, the value of the top Yukawa coupling and the sign of the WWh coupling may be probed for Higgs masses above 150 GeV, where WW and ZZ are the dominant Higgs decays. We consider Higgs masses of m{sub h} = 120, 150, 180, and 200 GeV and devise experimental cuts to extract the signal from SM backgrounds and measure the top Yukawa coupling.

Barger, V.; McCaskey, M.; Shaughnessy, G.; High Energy Physics; Univ. of Wisconsin at Madison; Northwestern Univ.

2010-02-01T23:59:59.000Z

245

Quark Interactions  

NLE Websites -- All DOE Office Websites (Extended Search)

Interacciones del quark Interacciones del quark Volver Principal ESTOY PERDIDO!!! Los quarks tienen carga eléctrica, por lo que sufren interacciones electromagnéticas. Los quarks tienen carga de color, de modo que sufren las interacciones fuertes. Las interacciones fuertes causan que los quarks se combinen formando hadrones. Las interacciones fuertes residuales mantienen a los hadrones juntos, para formar núcleos. Los diferentes tipos de quark (u, d, c, ...) se denominan sabores. El sabor sólo se altera por medio de interacciones debiles cargadas. Por ejemplo: Todos los quarks del lado izquierdo también aparecen del lado derecho . Sin embargo, cuando un quark emite un bosón ( virtual) W+ o W-, debe cambiar su carga eléctrica y, por lo tanto, su sabor. El proceso débil predominante es el que involucra transiciones entre quarks de la misma

246

Searches for new quarks and leptons in Z boson decays  

SciTech Connect

Searches for the decay of Z bosons into pairs of new quarks and leptons in a data sample including 455 hadronic Z decays are presented. The Z bosons were produced in electon-positron annihilations at the SLAC Linear Collider operating in the center-of-mass energy range from 89.2 to 93.0 GeV. The Standard Model provides no prediction for fermion masses and does not exclude new generations of fermions. The existence and masses of these new particles may provide valuable information to help understand the pattern of fermion masses, and physics beyond the Standard Model. Specific searches for top quarks and sequential fourth generation charge--1/3(b{prime}) quarks are made considering a variety of possible standard and non-standard decay modes. In addition, searches for sequential fourth generation massive neutrinos {nu}{sub 4} and their charged lepton partners L{sup {minus}} are pursued. The {nu}{sub 4} may be stable or decay through mixing to the lighter generations. The data sample is examined for new particle topologies of events with high-momentum isolated tracks, high-energy isolated photons, spherical event shapes, and detached vertices. No evidence is observed for the production of new quarks and leptons. 95% confidence lower mass limits of 40.7 GeV/c{sup 2} for the top quark and 42.0 GeV/c{sup 2} for the b{prime}-quark mass are obtained regardless of the branching fractions to the considered decay modes. A significant range of mixing matrix elements of {nu}{sub 4} to other generation neutrinos for a {nu}{sub 4} mass from 1 GeV/c{sup 2} to 43 GeV/c{sup 2} is excluded at 95% confidence level. Measurements of the upper limit of the invisible width of the Z exclude additional values of the {nu}{sub 4} mass and mixing matrix elements, and also permit the exclusion of a region in the L{sup {minus}} mass versus {nu}{sub 4} mass plane.

Van Kooten, R.J.

1990-06-01T23:59:59.000Z

247

Quark Chart  

NLE Websites -- All DOE Office Websites (Extended Search)

Es muy difcil determinar la masa, o incluso definir qu se entiende por masa de un quark, dado que un quark no se puede aislar. sto es especialmente cierto para la...

248

Singlet Free Energies of a Static Quark-Antiquark Pair  

E-Print Network (OSTI)

We study the singlet part of the free energy of a static quark anti-quark pair at finite temperature in three flavor QCD with degenerate quark masses using $N_{\\tau}=4$ and 6 lattices with Asqtad staggered fermion action. We look at thermodynamics of the system around phase transition and study its scaling with lattice spacing and quark masses.

Konstantin Petrov

2004-09-01T23:59:59.000Z

249

Funny Quarks  

NLE Websites -- All DOE Office Websites (Extended Search)

graciosos quarks graciosos quarks Volver Principal ESTOY PERDIDO!!! Un poco de la historia del quark: En 1964 Murray Gell-Mann y George Zweig sugirieron que cientos de las partículas conocidas hasta el momento, podrían ser explicadas como una combinación de sólo 3 partículas fundamentales. Gell-Mann eligió el nombre caprichoso de "quarks" para estos constituyentes. Esta palabra aparece en la frase "three quarks for Muster Mark" en la novela de James Joyce, Finnegan's Wake. La parte revolucionaria de la idea era que ellos debieron asignarle a los quarks cargas eléctricas de 2/3 y -1/3 (en unidades de la carga del protón): nunca habían sido observadas cargas como esas. Primero los quarks fueron considerados como un truco matemático, pero los experimentos

250

Kinematical evidence for top pairs at the Tevatron  

SciTech Connect

We present a top search analysis of W+jet events which combines a study of the kinematic features of the events with a search for bottom quarks.

Grassmann, H. [Fermi National Accelerator Lab., Batavia, IL (United States)]|[Duke Univ., Durham, NC (United States); CDF Collaboration

1994-09-01T23:59:59.000Z

251

Analyzing the scalar top co-annihilation region at the ILC  

SciTech Connect

The Minimal Supersymmetric Standard Model opens the possibility of electroweak baryogenesis provided that the light scalar top quark (stop) is lighter than the top quark. In addition, the lightest neutralino is an ideal candidate to explain the existence of dark matter. For a light stop with mass close to the lightest neutralino, the stop-neutralino co-annihilation mechanism becomes efficient, thus rendering the predicted dark matter density compatible with observations. Such a stop may however remain elusive at hadron colliders. Here it is shown that a future linear collider provides a unique opportunity to detect and study the light stop. The production of stops with small stop-neutralino mass differences is studied in a detailed experimental analysis with a realistic detector simulation including a CCD vertex detector for flavor tagging. Furthermore, the linear collider, by precision measurements of superpartner masses and mixing angles, also allows to determine the dark matter relic density with an accuracy comparable to recent astrophysical observations.

Carena, M.; /Fermilab; Finch, A.; /Lancaster U.; Freitas, A.; Milstene, C.; /Fermilab; Nowak, H.; /DESY, Zeuthen; Sopczak, A.; /Lancaster U.

2005-08-01T23:59:59.000Z

252

A study of the ultrahigh-energy cosmic ray mass composition with the MACRO and EAS-TOP experiments  

SciTech Connect

Two components of cosmic-ray-induced air showers are measured simultaneously at the Gran Sasso Laboratory: the electromagnetic shower at the ground surface by the EAS-TOP extensive air shower array, and the deep-underground muons by the MACRO experiment. The two independent data sets collected during 96.3 days of simultaneous running are combined, and underground muon multiplicity distributions are obtained for anticoincident events (no surface trigger) and high-energy, coincident events. These categories correspond to ranges in primary energy from about 2 x 10{sup 3} GeV to a few times 10{sup 5} GeV, and from 1.5 x 10{sup 5} GeV to about 10{sup 7} GeV, respectively. The experimental shower size and muon multiplicity distributions, as well as the distribution of mean muon multiplicity as a function of shower size (N{sub mu} - log(N{sub mu}) relation), are compared to the ones obtained with Monte Carlo calculations using various trial compositions as input. This is done in an effort to discriminate between these models of primary cosmic-ray mass composition at and above the `kneel` in the all-particle spectrum, where contradictory experimental evidence exists and where a knowledge of the composition would bear upon possible mechanisms for cosmic-ray acceleration and propagation. Detailed studies of simulated anticoincident event rates uncover problems with generator used, with between 25 and 40% too few high-energy muons created. This, combined with the dependence of absolute event rates on the assumed differential primary energy spectra, hampers the interpretation in terms of composition of underground muon or surface air shower data taken separately. However, the N{sub mu} - log(N{sub e}) relation is independent of the spectra or overall Monte Carlo normalization problems. The simulated N{sub mu} - log (N{sub e}) relation for coincident events is found to be inconsistent with the possibility that the cosmic ray flux becomes proton-dominated at and above the knee.

Coutu, S.

1993-12-31T23:59:59.000Z

253

Quark Charge  

NLE Websites -- All DOE Office Websites (Extended Search)

Bruchteile von 23 und 13 der elektrischen Ladung. Sie werden aber immer nur in Teilchen gefunden, die eine ganzzahlige elektrische Ladung haben. Isolierte Quarks knnen nicht...

254

Jet quenching and heavy quarks  

E-Print Network (OSTI)

Jet quenching and more generally physics at high transverse momentum P_T scales is a cornerstone of the heavy-ion physics program at the LHC. In this work, the current understanding of jet quenching in terms of a QCD shower evolution being modified by the surrounding medium is reviewed along with the evidence for this picture from light parton high P_T observables. Conceptually, the same QCD shower description should also be relevant for heavy quarks, but with several important modifications introduced by the quark masses. Thus especially in the limit of small jet energy over quark mass E_jet/m_q, the relevant physics may be rather different from light quark jets, and several attempts to explain the observed phenomenology of heavy quarks at high P_T are discussed here.

Thorsten Renk

2013-09-12T23:59:59.000Z

255

Single Top Production at the Tevatron  

SciTech Connect

We present recent results of single top quark production in the lepton plus jet final state, performed by the CDF and D0 collaborations based on 7.5 and 5.4 fb{sup -1} of p{bar p} collision data collected at {radical}s = 1.96 TeV from the Fermilab Tevatron collider. Multivariate techniques are used to separate the single top signal from the backgrounds. Both collaborations present measurements of the single top quark cross section and the CKM matrix element |V{sub tb}|. A search for anomalous Wtb coupling from D0 is also presented.

Wu, Zhenbin; /Baylor U.

2012-05-01T23:59:59.000Z

256

W Transverse Mass  

NLE Websites -- All DOE Office Websites (Extended Search)

Some Data Analysis Some Data Analysis The Tevatron produces millions of collisions each second in CDF and DZero. The detectors have hardware triggers to decide if a collision is "interesting," that is it contains a candidate event for any one of a number studies. Our dataset contains 48,844 candidate events for a W mass study. There are other datasets to study Z mass, top and b quarks, QCD, etc. Why don't all the W decays give exactly the same mass? Are all these candidates really Ws? What if we chose only some of these data. How would our choice effect the value of the transverse mass? Work with your classmates. Test the data to see what you can learn. Help with data analysis. Record the best estimate of the W transverse mass from your data analysis. Explain which data you used and why. Check with your classmates and explain any differences between your estimate and theirs.

257

Quark Lepton Similarity  

E-Print Network (OSTI)

We propose the lepton mixing matrix at high energy scale to be connected to quark mixing matrix by the similar transformation. The similarity between CKM and PMNS significantly narrows down the ranges in physical parameters. The condition requires $\\sin\\theta_{13}$ not to be larger than 0.15, masses to be of quasi-degenerate normal ordering, and $\\tan\\beta$ to be large.

Seungsu Hwang; Kim Siyeon

2010-08-20T23:59:59.000Z

258

Static quark free energies at finite temperature with two flavors of improved Wilson quarks  

E-Print Network (OSTI)

Polyakov loop correlations at finite temperature in two-flavor QCD are studied in lattice simulations with the RG-improved gluon action and the clover-improved Wilson quark action. From the simulations on a $16^3 \\times 4$ lattice, we extract the free energies, the effective running coupling $g_{\\rm eff}(T)$ and the Debye screening mass $m_D(T)$ for various color channels of heavy quark--quark and quark--anti-quark pairs above the critical temperature. The free energies are well approximated by the screened Coulomb form with the appropriate Casimir factors. The magnitude and the temperature dependence of the Debye mass are compared to those of the next-to-leading order thermal perturbation theory and to a phenomenological formula given in terms of $g_{\\rm eff}(T)$. Also we made a comparison between our results with the Wilson quark and those with the staggered quark previously reported.

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

2006-10-02T23:59:59.000Z

259

Measurement of the top-antitop production cross section in the tau+jets channel in pp collisions at sqrt(s) = 7 TeV  

E-Print Network (OSTI)

The top-quark pair production cross section in 7 TeV center-of-mass energy proton-proton collisions is measured using data collected by the CMS detector at the LHC. The measurement uses events with one jet identified as a hadronically decaying tau lepton and at least four additional energetic jets, at least one of which is identified as coming from a b quark. The analyzed data sample corresponds to an integrated luminosity of 3.9 inverse femtobarns recorded by a dedicated multijet plus hadronically decaying tau trigger. A neural network has been developed to separate the top-quark pairs from the W+jets and multijet backgrounds. The measured value of sigma(ttbar) = 152 +/- 12 (stat.) +/- 32 (syst.) +/- 3 (lum.) pb is consistent with the standard model predictions.

CMS Collaboration

2013-01-24T23:59:59.000Z

260

Bounds on the Higgs Mass in the Standard Model and Minimal Supersymmetric Standard Model  

E-Print Network (OSTI)

We present bounds on the Higgs mass in the Standard Model and in the Minimal Supersymmetric Standard Model using the effective potential with next-to-leading logarithms resummed by the renormalization group equations, and physical (pole) masses for the top quark and Higgs boson. In the Standard Model we obtain lower bounds from stability requirements: they depend on the top mass and the cutoff scale. In the Minimal Supersymmetric Standard Model we obtain upper bounds which depend on the top mass and the scale of supersymmetry breaking. A Higgs mass measurement could discriminate, depending on the top mass, between the two models. Higgs discovery at LEP-200 can put an upper bound on the scale of new physics.

Mariano Quirós

1994-11-26T23:59:59.000Z

Note: This page contains sample records for the topic "top quark mass" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

QuarkNet  

NLE Websites -- All DOE Office Websites (Extended Search)

QuarkNet: The science connection you've been waiting for! QuarkNet: The science connection you've been waiting for! The Opportunity: "Your program rejuvenates my soul. It connects me with a cadre of intelligent and excited educators. It reinvigorates my teaching and provides me avenues to extend and enliven the projects that I can offer my students. Without the Quarknet program I am sure that I would have left teaching years ago." The Players: High school students, teachers and physicsts working together on physics research projects exploring the hidden nature of matter, energy, space and time. The Questions: What are the origins of mass? Can the basic forces of nature be unified? How did the universe begin? How will it evolve? LHC & Fermilab Links For Teachers For Students CERN Homepage ATLAS Experiment

262

q007.dvi  

NLE Websites -- All DOE Office Websites (Extended Search)

Top +1 A REVIEW GOES HERE - Check our WWW List of Reviews t-QUARK MASS t-QUARK MASS t-QUARK MASS t-QUARK MASS We first list the direct measurements of the top quark mass which...

263

Quark flavour mixing and the exponential form of the Kobayashi ...  

Science Conference Proceedings (OSTI)

At present the Higgs boson remains the only one missing piece of the standard model to be confirmed experimentally. The quark mass eigenstates differ from ...

264

quarks_q000-web.dvi  

NLE Websites -- All DOE Office Websites (Extended Search)

- 1- QUARK MASSES Updated Jan 2012 by A.V. Manohar (University of California, San Diego) and C.T. Sachrajda (University of Southampton) A. Introduction This note discusses some of...

265

The Top Window for dark matter  

E-Print Network (OSTI)

We investigate a scenario that the top quark is the only window to the dark matter particle. We use the effective Lagrangian approach to write down the interaction between the top quark and the dark matter particle. Requiring the dark matter satisfying the relic density we obtain the size of the effective interaction. We show that the scenario can be made consistent with the direct and indirect detection experiments by adjusting the size of the effective coupling. Finally, we calculate the production cross section for $t\\bar t + \\chi \\bar \\chi$ at the Large Hadron Collider (LHC), which will give rise to an interesting signature of a top-pair plus large missing energy.

Kingman Cheung; Kentarou Mawatari; Eibun Senaha; Po-Yan Tseng; Tzu-Chiang Yuan

2010-09-03T23:59:59.000Z

266

quark_s027-web.dvi  

NLE Websites -- All DOE Office Websites (Extended Search)

FREE QUARK SEARCHES The basis for much of the theory of particle scattering and hadron spectroscopy is the construction of the hadrons from a set of fractionally charged...

267

QUARK MATTER IN MASSIVE COMPACT STARS  

SciTech Connect

The recent observation of the pulsar PSR J1614-2230 with a mass of 1.97 {+-} 0.04 M{sub sun} gives a strong constraint on the quark and nuclear matter equations of state (EoS). We explore the parameter ranges for a parameterized EoS for quark stars. We find that strange stars, made of absolutely stable strange quark matter, comply with the new constraint only if effects from the strong coupling constant and color-superconductivity are taken into account. Hybrid stars, compact stars with a quark matter core and a hadronic outer layer, can be as massive as 2 M{sub sun}, but only for a significantly limited range of parameters. We demonstrate that the appearance of quark matter in massive stars crucially depends on the stiffness of the nuclear matter EoS. We show that the masses of hybrid stars stay below the ones of hadronic and pure quark stars, due to the softening of the EoS at the quark-hadron phase transition.

Weissenborn, Simon; Pagliara, Giuseppe; Schaffner-Bielich, Juergen [Institute for Theoretical Physics, Ruprecht-Karls University, 69120 Heidelberg (Germany); Sagert, Irina [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Hempel, Matthias [Department of Physics, University of Basel, 4056 Basel (Switzerland)

2011-10-10T23:59:59.000Z

268

Stability windows for proto-quark stars  

E-Print Network (OSTI)

We investigate the existence of possible stable strange matter and related stability windows at finite temperature for different models that are generally applied to describe quark stars, namely, the quark-mass density dependent model, the MIT bag model and the Nambu-Jona-Lasinio model. We emphasize that, although the limits for stable strange matter depend on a comparison with the ground state of 56Fe, which is a zero temperature state, the quantity that has to be used in the search for strange matter in proto-quark stars is the free energy and we analyze stability windows up to temperatures of the order of 40 MeV. The effects of strong magnetic fields on stability windows are computed and the resulting mass-radius relations for different stages of the proto-quark star are analyzed.

V. Dexheimer; J. R. Torres; D. P. Menezes

2013-03-20T23:59:59.000Z

269

QCD Thermodynamics with Three Flavors of Improved Staggered Quarks  

E-Print Network (OSTI)

We report on a study of QCD thermodynamics with three flavors of quarks, using a Symanzik improved gauge action and the Asqtad O(a^2) improved staggered quark action. Simulations were carried out with lattice spacings 1/4T, 1/6T and 1/8T both for three degenerate quarks with masses less than or equal to the strange quark mass, m_s, and for degenerate up and down quarks with masses in the range 0.1 m_s \\leq m_{u,d} \\leq 0.6 m_s, and the strange quark mass fixed near its physical value. We present results for standard thermodynamics quantities, such as the Polyakov loop, the chiral order parameter and its susceptibility. For the quark masses studied to date we find a rapid crossover rather than a bona fide phase transition. We have carried out the first calculations of quark number susceptibilities with three flavors of sea quarks. These quantities are of physical interest because they are related to event-by-event fluctuations in heavy ion collision experiments. Comparison of susceptibilities at different lattice spacings show that our results are close to the continuum values.

The MILC Collaboration; C. Bernard; T. Burch; C. DeTar; Steven Gottlieb; E. B. Gregory; U. M. Heller; J. Osborn; R. Sugar; D. Toussaint

2004-05-27T23:59:59.000Z

270

Light quark physics from lattice QCD  

E-Print Network (OSTI)

I review lattice calculations of quantities that involve light quarks, including light quark masses, the vector form factor f_+(0) needed for semileptonic kaon decays, and kaon mixing. Results for most of these quantities are now available from multiple groups. Averages of these results are presented, along with a discussion of the methodology behind the averaging procedure. Recent progress in calculations of K->pi pi matrix elements is also reviewed.

Jack Laiho

2011-06-02T23:59:59.000Z

271

Light front approach to correlations in hot quark matter  

E-Print Network (OSTI)

We investigate two-quark correlations in hot and dense quark matter. To this end we use the light front field theory extended to finite temperature $T$ and chemical potential $\\mu$. Therefore it is necessary to develop quantum statistics formulated on the light front plane. As a test case for light front quantization at finite $T$ and $\\mu$ we consider the NJL model. The solution of the in-medium gap equation leads to a constituent quark mass which depends on $T$ and $\\mu$. Two-quark systems are considered in the pionic and diquark channel. We compute the masses of the two-body system using a $T$-matrix approach.

S. Strauss; M. Beyer; S. Mattiello

2005-11-01T23:59:59.000Z

272

Free energies of heavy quarks in full-QCD lattice simulations with Wilson-type quark action  

E-Print Network (OSTI)

The free energy between a static quark and an antiquark is studied by using the color-singlet Polyakov-line correlation at finite temperature in lattice QCD with 2+1 flavors of improved Wilson quarks. From the simulations on $32^3 \\times 12$, 10, 8, 6, 4 lattices in the high temperature phase, based on the fixed scale approach, we find that, the heavy-quark free energies at short distance converge to the heavy-quark potential evaluated from the Wilson loop at zero temperature, in accordance with the expected insensitivity of short distance physics to the temperature. At long distance, the heavy-quark free energies approach to twice the single-quark free energies, implying that the interaction between heavy quarks is screened. The Debye screening mass obtained from the long range behavior of the free energy is compared with the results of thermal perturbation theory.

Y. Maezawa; S. Aoki; S. Ejiri; T. Hatsuda; N. Ishii; K. Kanaya; H. Ohno; T. Umeda

2009-07-24T23:59:59.000Z

273

Dragging Heavy Quarks in Quark Gluon Plasma at the Large Hadron Collider  

E-Print Network (OSTI)

The drag and diffusion coefficients of charm and bottom quarks propagating through quark gluon plasma (QGP) have been evaluated for conditions relevant to nuclear collisions at Large Hadron Collider (LHC). The dead cone and Landau-Pomeronchuk-Migdal (LPM) effects on radiative energy loss of heavy quarks have been considered. Both radiative and collisional processes of energy loss are included in the {\\it effective} drag and diffusion coefficients. With these effective transport coefficients we solve the Fokker Plank (FP) equation for the heavy quarks executing Brownian motion in the QGP. The solution of the FP equation has been used to evaluate the nuclear suppression factor, $R_{\\mathrm AA}$ for the non-photonic single electron spectra resulting from the semi-leptonic decays of hadrons containing charm and bottom quarks. The effects of mass on $R_{\\mathrm AA}$ has also been highlighted.

Santosh K Das; Jan-e Alam; Payal Mohanty

2010-03-29T23:59:59.000Z

274

Report of the Quark Flavor Physics Working Group  

E-Print Network (OSTI)

This report represents the response of the Intensity Frontier Quark Flavor Physics Working Group to the Snowmass charge. We summarize the current status of quark flavor physics and identify many exciting future opportunities for studying the properties of strange, charm, and bottom quarks. The ability of these studies to reveal the effects of new physics at high mass scales make them an essential ingredient in a well-balanced experimental particle physics program.

J. N. Butler; Z. Ligeti; J. L. Ritchie; V. Cirigliano; S. Kettell; R. Briere; A. A. Petrov; A. Schwartz; T. Skwarnicki; J. Zupan; N. Christ; S. R. Sharpe; R. S. Van de Water; W. Altmannshofer; N. Arkani-Hamed; M. Artuso; D. M. Asner; C. Bernard; A. J. Bevan; M. Blanke; G. Bonvicini; T. E. Browder; D. A. Bryman; P. Campana; R. Cenci; D. Cline; J. Comfort; D. Cronin-Hennessy; A. Datta; S. Dobbs; M. Duraisamy; A. X. El-Khadra; J. E. Fast; R. Forty; K. T. Flood; T. Gershon; Y. Grossman; B. Hamilton; C. T. Hill; R. J. Hill; D. G. Hitlin; D. E. Jaffe; A. Jawahery; C. P. Jessop; A. L. Kagan; D. M. Kaplan; M. Kohl; P. Krizan; A. S. Kronfeld; K. Lee; L. S. Littenberg; D. B. MacFarlane; P. B. Mackenzie; B. T. Meadows; J. Olsen; M. Papucci; Z. Parsa; G. Paz; G. Perez; L. E. Piilonen; K. Pitts; M. V. Purohit; B. Quinn; B. N. Ratcliff; D. A. Roberts; J. L. Rosner; P. Rubin; J. Seeman; K. K. Seth; B. Schmidt; A. Schopper; M. D. Sokoloff; A. Soni; K. Stenson; S. Stone; R. Sundrum; R. Tschirhart; A. Vainshtein; Y. W. Wah; G. Wilkinson; M. B. Wise; E. Worcester; J. Xu; T. Yamanaka

2013-11-05T23:59:59.000Z

275

The Onset of Quark-Hadron Duality in Pion Electroproduction  

DOE Green Energy (OSTI)

A large data set of charged-pion electroproduction from both hydrogen and deuterium targets has been obtained spanning the low-energy residual-mass region. These data conclusively show the onset of the quark-hadron duality phenomenon, as predicted for high-energy hadron electroproduction. We construct several ratios from these data to exhibit the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark-to- pion production mechanisms.

Tigran Navasardyan; Gary Adams; Abdellah Ahmidouch; Tatiana Angelescu; John Arrington; Razmik Asaturyan; O. Baker; Nawal Benmouna; Crystal Bertoncini; Henk Blok; Werner Boeglin; Peter Bosted; Herbert Breuer; Michael Christy; Simon Connell; Yonggang Cui; Mark Dalton; Samuel Danagoulian; Donal Day; T. Dodario; James Dunne; Dipangkar Dutta; Najib Elkhayari; Rolf Ent; Howard Fenker; Valera Frolov; Liping Gan; David Gaskell; Kawtar Hafidi; Wendy Hinton; Roy Holt; Tanja Horn; Garth Huber; Ed Hungerford; Xiaodong Jiang; Mark Jones; Kyungseon Joo; Narbe Kalantarians; James Kelly; Cynthia Keppel; Edward Kinney; V. Kubarovski; Ya Li; Yongguang Liang; Simona Malace; Pete Markowitz; Erin McGrath; Daniella Mckee; David Meekins; Hamlet Mkrtchyan; Brian Moziak; Gabriel Niculescu; Maria-Ioana Niculescu; Allena Opper; Tanya Ostapenko; Paul Reimer; Joerg Reinhold; Julie Roche; Stephen Rock; Elaine Schulte; Edwin Segbefia; C. Smith; G.R. Smith; Paul Stoler; Vardan Tadevosyan; Liguang Tang; Maurizio Ungaro; Alicia Uzzle; Sandra Vidakovic; Anthony Villano; William Vulcan; Miao Wang; Glen Warren; Frank Wesselmann; Bogdan Wojtsekhowski; Stephen Wood; Chuncheng Xu; Lulin Yuan; Xiaochao Zheng; Hong Guo Zhu

2006-08-29T23:59:59.000Z

276

B-meson decay constants with domain-wall light quarks and nonperturbatively tuned relativistic b-quarks  

E-Print Network (OSTI)

We report on our progress to obtain the decay constants f_B and f_Bs from lattice-QCD simulations on the RBC-UKQCD Collaborations 2+1 flavor domain-wall Iwasaki lattices. Using domain-wall light quarks and relativistic b-quarks we analyze data with several partially quenched light-quark masses at two lattice spacings of a approx 0.11 fm and a approx 0.08 fm.

Oliver Witzel

2013-11-01T23:59:59.000Z

277

Cooling of Neutron Stars with Color Superconducting Quark Cores  

E-Print Network (OSTI)

We show that within a recently developed nonlocal chiral quark model the critical density for a phase transition to color superconducting quark matter under neutron star conditions can be low enough for these phases to occur in compact star configurations with masses below 1.3 M_solar. We study the cooling of these objects in isolation for different values of the gravitational mass. Our equation of state (EoS) allows for 2SC quark matter with a large quark gap \\~100 MeV for u and d quarks of two colors that coexists with normal quark matter within a mixed phase in the hybrid star interior. We argue that, if the phases with unpaired quarks were allowed, the corresponding hybrid stars would cool too fast. If they occured for M cooling data existing by today. We discuss a "2SC+X" phase, as a possibility to have all quarks paired in two-flavor quark matter under neutron star constraints, where the X-gap is of the order of 10 keV - 1 MeV. Density independent gaps do not allow to fit the cooling data. Only the presence of an X-gap that decreases with increase of the density could allow to appropriately fit the data in a similar compact star mass interval to that following from a purely hadronic model. This scenario is suggested as an alternative explanation of the cooling data in the framework of a hybrid star model.

Hovik Grigorian; David Blaschke; Dmitri Voskresensky

2004-11-22T23:59:59.000Z

278

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

Science Conference Proceedings (OSTI)

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.

Gomez Dumm, D., E-mail: dumm@fisica.unlp.edu.ar [UNLP, IFLP, Departamento de Fisica (Argentina); Contrera, G. A., E-mail: contrera@tandar.cnea.gov.ar [CONICET (Argentina)

2012-06-15T23:59:59.000Z

279

Combined search for the quarks of a sequential fourth generation  

E-Print Network (OSTI)

Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up- and down-type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant CKM matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. This result significantly reduces the allowed parameter space for a fourt...

Chatrchyan, Serguei; Sirunyan, Albert M; Tumasyan, Armen; Adam, Wolfgang; Aguilo, Ernest; Bergauer, Thomas; Dragicevic, Marko; Erö, Janos; Fabjan, Christian; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hammer, Josef; Hörmann, Natascha; Hrubec, Josef; Jeitler, Manfred; Kiesenhofer, Wolfgang; Knünz, Valentin; Krammer, Manfred; Krätschmer, Ilse; Liko, Dietrich; Mikulec, Ivan; Pernicka, Manfred; Rahbaran, Babak; Rohringer, Christine; Rohringer, Herbert; Schöfbeck, Robert; Strauss, Josef; Taurok, Anton; Waltenberger, Wolfgang; Walzel, Gerhard; Widl, Edmund; Wulz, Claudia-Elisabeth; Mossolov, Vladimir; Shumeiko, Nikolai; Suarez Gonzalez, Juan; Bansal, Monika; Bansal, Sunil; Cornelis, Tom; De Wolf, Eddi A; Janssen, Xavier; Luyckx, Sten; Mucibello, Luca; Ochesanu, Silvia; Roland, Benoit; Rougny, Romain; Selvaggi, Michele; Staykova, Zlatka; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Van Spilbeeck, Alex; Blekman, Freya; Blyweert, Stijn; D'Hondt, Jorgen; Gonzalez Suarez, Rebeca; Kalogeropoulos, Alexis; Maes, Michael; Olbrechts, Annik; Van Doninck, Walter; Van Mulders, Petra; Van Onsem, Gerrit Patrick; Villella, Ilaria; Clerbaux, Barbara; De Lentdecker, Gilles; Dero, Vincent; Gay, Arnaud; Hreus, Tomas; Léonard, Alexandre; Marage, Pierre Edouard; Mohammadi, Abdollah; Reis, Thomas; Thomas, Laurent; Vander Marcken, Gil; Vander Velde, Catherine; Vanlaer, Pascal; Wang, Jian; Adler, Volker; Beernaert, Kelly; Cimmino, Anna; Costantini, Silvia; Garcia, Guillaume; Grunewald, Martin; Klein, Benjamin; Lellouch, Jérémie; Marinov, Andrey; Mccartin, Joseph; Ocampo Rios, Alberto Andres; Ryckbosch, Dirk; Strobbe, Nadja; Thyssen, Filip; Tytgat, Michael; Verwilligen, Piet; Walsh, Sinead; Yazgan, Efe; Zaganidis, Nicolas; Basegmez, Suzan; Bruno, Giacomo; Castello, Roberto; Ceard, Ludivine; Delaere, Christophe; Du Pree, Tristan; Favart, Denis; Forthomme, Laurent; Giammanco, Andrea; Hollar, Jonathan; Lemaitre, Vincent; Liao, Junhui; Militaru, Otilia; Nuttens, Claude; Pagano, Davide; Pin, Arnaud; Piotrzkowski, Krzysztof; Schul, Nicolas; Vizan Garcia, Jesus Manuel; Beliy, Nikita; Caebergs, Thierry; Daubie, Evelyne; Hammad, Gregory Habib; Alves, Gilvan; Correa Martins Junior, Marcos; De Jesus Damiao, Dilson; Martins, Thiago; Pol, Maria Elena; Henrique Gomes E Souza, Moacyr; Aldá Júnior, Walter Luiz; Carvalho, Wagner; Custódio, Analu; Da Costa, Eliza Melo; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Matos Figueiredo, Diego; Mundim, Luiz; Nogima, Helio; Oguri, Vitor; Prado Da Silva, Wanda Lucia; Santoro, Alberto; Soares Jorge, Luana; Sznajder, Andre; Souza Dos Anjos, Tiago; Bernardes, Cesar Augusto; De Almeida Dias, Flavia; Tomei, Thiago; De Moraes Gregores, Eduardo; Lagana, Caio; Da Cunha Marinho, Franciole; Mercadante, Pedro G; Novaes, Sergio F; Padula, Sandra; Genchev, Vladimir; Iaydjiev, Plamen; Piperov, Stefan; Rodozov, Mircho; Stoykova, Stefka; Sultanov, Georgi; Tcholakov, Vanio; Trayanov, Rumen; Vutova, Mariana; Dimitrov, Anton; Hadjiiska, Roumyana; Kozhuharov, Venelin; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Jiang, Chun-Hua; Liang, Dong; Liang, Song; Meng, Xiangwei; Tao, Junquan; Wang, Jian; Wang, Xianyou; Wang, Zheng; Xiao, Hong; Xu, Ming; Zang, Jingjing; Zhang, Zhen; Asawatangtrakuldee, Chayanit; Ban, Yong; Guo, Shuang; Guo, Yifei; Li, Wenbo; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Teng, Haiyun; Wang, Dayong; Zhang, Linlin; Zhu, Bo; Zou, Wei; Avila, Carlos; Gomez, Juan Pablo; Gomez Moreno, Bernardo; Osorio Oliveros, Andres Felipe; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Plestina, Roko; Polic, Dunja; Puljak, Ivica; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Duric, Senka; Kadija, Kreso; Luetic, Jelena; Morovic, Srecko; Attikis, Alexandros; Galanti, Mario; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Finger, Miroslav; Finger Jr, Michael; Assran, Yasser; Elgammal, Sherif; Ellithi Kamel, Ali; Khalil, Shaaban; Mahmoud, Mohammed; Radi, Amr; Kadastik, Mario; Müntel, Mait; Raidal, Martti; Rebane, Liis; Tiko, Andres; Eerola, Paula; Fedi, Giacomo; Voutilainen, Mikko; Härkönen, Jaakko; Heikkinen, Mika Aatos; Karimäki, Veikko; Kinnunen, Ritva; Kortelainen, Matti J; Lampén, Tapio; Lassila-Perini, Kati; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Mäenpää, Teppo; Peltola, Timo; Tuominen, Eija; Tuominiemi, Jorma; Tuovinen, Esa; Ungaro, Donatella; Wendland, Lauri; Banzuzi, Kukka; Karjalainen, Ahti; Korpela, Arja; Tuuva, Tuure; Besancon, Marc; Choudhury, Somnath

2012-01-01T23:59:59.000Z

280

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

SciTech Connect

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.

Contrera, G. A. [CONICET, Rivadavia 1917, 1033 Buenos Aires (Argentina); Physics Department, Centro Atomico Constituyentes, Buenos Aires (Argentina); Gomez Dumm, D. [CONICET, Rivadavia 1917, 1033 Buenos Aires (Argentina); IFLP, Dpto. de Fisica, Universidad Nacional de La Plata, C.C. 67, (1900) La Plata (Argentina); Scoccola, N. N. [CONICET, Rivadavia 1917, 1033 Buenos Aires (Argentina); Universidad Favaloro, Solis 453, 1078 Buenos Aires (Argentina)

2010-11-12T23:59:59.000Z

Note: This page contains sample records for the topic "top quark mass" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

–1– FREE QUARK SEARCHES  

E-Print Network (OSTI)

The basis for much of the theory of particle scattering and hadron spectroscopy is the construction of the hadrons from a set of fractionally charged constituents (quarks). A central but unproven hypothesis of this theory, Quantum Chromodynamics, is that quarks cannot be observed as free particles but are confined to mesons and baryons. Experiments show that it is at best difficult to “unglue” quarks. Accelerator searches at increasing energies have produced no evidence for free quarks, while only a few cosmic-ray and matter searches have produced uncorroborated events. This compilation is only a guide to the literature, since the quoted experimental limits are often only indicative. Reviews

unknown authors

2004-01-01T23:59:59.000Z

282

Quark Matter 2004  

NLE Websites -- All DOE Office Websites (Extended Search)

Seventeenth International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2004) took place in Oakland, California from January 11 - 17, 2004. The location...

283

–1– FREE QUARK SEARCHES  

E-Print Network (OSTI)

The basis for much of the theory of particle scattering and hadron spectroscopy is the construction of the hadrons from a set of fractionally charged constituents (quarks). A central but unproven hypothesis of this theory, Quantum Chromodynamics, is that quarks cannot be observed as free particles but are confined to mesons and baryons. Experiments show that it is at best difficult to “unglue” quarks. Accelerator searches at increasing energies have produced no evidence for free quarks, while only a few cosmic-ray and matter searches have produced uncorroborated events. This compilation is only a guide to the literature, since the quoted experimental limits are often only indicative. Reviews

unknown authors

2008-01-01T23:59:59.000Z

284

–1– FREE QUARK SEARCHES  

E-Print Network (OSTI)

The basis for much of the theory of particle scattering and hadron spectroscopy is the construction of the hadrons from a set of fractionally charged constituents (quarks). A central but unproven hypothesis of this theory, Quantum Chromodynamics, is that quarks cannot be observed as free particles but are confined to mesons and baryons. Experiments show that it is at best difficult to “unglue” quarks. Accelerator searches at increasing energies have produced no evidence for free quarks, while only a few cosmic-ray and matter searches have produced uncorroborated events. This compilation is only a guide to the literature, since the quoted experimental limits are often only indicative. Reviews

unknown authors

2006-01-01T23:59:59.000Z

285

Deciphering top flavor violation at the LHC with B factories  

E-Print Network (OSTI)

The LHC will have unprecedented sensitivity to flavor-changing neutral current (FCNC) top quark decays, whose observation would be a clear sign of physics beyond the standard model. Although many details of top flavor violation are model dependent, the standard model gauge symmetries relate top FCNCs to other processes, which are strongly constrained by existing data. We study these constraints in a model independent way, using a low energy effective theory from which the new physics is integrated out. We consider the most important operators which contribute to top FCNCs and analyze the current constraints on them. We find that the data rule out top FCNCs at a level observable at the LHC due to most of the operators comprising left-handed first or second generation quark fields, while there remains a substantial window for top decays mediated by operators with right-handed charm or up quarks. If FCNC top decays are observed at the LHC, such an analysis may help decipher the underlying physics.

Patrick J. Fox; Zoltan Ligeti; Michele Papucci; Gilad Perez; Matthew D. Schwartz

2007-04-12T23:59:59.000Z

286

A top condensate model with a Higgs doublet and a Higgs triplet  

E-Print Network (OSTI)

We reconsider top condensate models from the perspective that not only two quark composite fields can form but also four quark ones. We obtain a model which contains a Higgs doublet and a Higgs triplet, where one of the neutral components of the Higgs triplet identifies with the Higgs boson found at the LHC. We discuss some of the phenomenological consequences.

Renata Jora; Salah Nasri; Joseph Schechter

2013-04-26T23:59:59.000Z

287

A top condensate model with a Higgs doublet and a Higgs triplet  

E-Print Network (OSTI)

We reconsider top condensate models from the perspective that not only two quark composite fields can form but also four quark ones. We obtain a model which contains a Higgs doublet and a Higgs triplet, where one of the neutral components of the Higgs triplet identifies with the Higgs boson found at the LHC. We discuss some of the phenomenological consequences.

Jora, Renata; Schechter, Joseph

2013-01-01T23:59:59.000Z

288

Ein Quark/Gluon Event  

NLE Websites -- All DOE Office Websites (Extended Search)

QuarkGluon Event Wie interpretiert man die Daten? Ein QuarkGluon Event Diese beiden Bilder zeigen Ergebnisse von Kollisionen, die in e- e+ Teilchenstrahlen stattfinden. Die...

289

If different types of quarks have...  

NLE Websites -- All DOE Office Websites (Extended Search)

are each made from three quarks. A proton is made up of two Up quarks and a Down quark while a neutron is made from two Down quarks and an Up quark. If protons and neutrons...

290

quark-web.dvi  

NLE Websites -- All DOE Office Websites (Extended Search)

FREE FREE QUARK SEARCHES The basis for much of the theory of particle scattering and hadron spectroscopy is the construction of the hadrons from a set of fractionally charged constituents (quarks). A central but unproven hypothesis of this theory, Quantum Chromodynamics, is that quarks cannot be observed as free particles but are confined to mesons and baryons. Experiments show that it is at best difficult to "unglue" quarks. Accelerator searches at increasing energies have pro- duced no evidence for free quarks, while only a few cosmic-ray and matter searches have produced uncorroborated events. This compilation is only a guide to the literature, since the quoted experimental limits are often only indicative. Reviews can be found in Refs. 1-4. References 1. M.L. Perl, E.R. Lee, and D. Lomba, Mod. Phys. Lett. A19, 2595 (2004). 2. P.F. Smith, Ann. Rev. Nucl. and Part. Sci. 39,

291

Searching for the fourth family quarks through anomalous decays  

Science Conference Proceedings (OSTI)

The flavor democracy hypothesis predicts the existence of the fourth standard model family. Because of the high masses of the fourth family quarks, their anomalous decays could be dominant if certain criteria are met. This will drastically change the search strategy at hadron colliders. We show that the fourth standard model family down quarks with masses up to 400-450 GeV can be observed (or excluded) via anomalous decays by Tevatron.

Sahin, M.; Sultansoy, S.; Turkoz, S. [TOBB University of Economics and Technology, Physics Division, Ankara (Turkey); TOBB University of Economics and Technology, Physics Division, Ankara, Turkey and Institute of Physics, National Academy of Sciences, Baku (Azerbaijan); Ankara University, Department of Physics, Ankara (Turkey)

2010-09-01T23:59:59.000Z

292

TopReX generator (version~3.25). Short manual  

E-Print Network (OSTI)

This is the manual of the specialized event generator TopReX 3.25. The generator provides the simulation of several important processes in pp and p pbar collisions, not implemented in PYTHIA (yet). Some of these processes include t-quarks whose spin polarizations are taken into account in the subsequent decay of the t-quarks. Several non-SM top quark decay channels are included, too. All calculated subprocesses can be accessed from PYTHIA as external processes. In addition, TopReX can be used as stand alone event generator, providing partonic final states before showering. In this mode the control of the event generation is taken by TopReX itself. A few simple examples of main routines, which show how to use TopReX in the different modes are discussed.

S. R. Slabospitsky; L. Sonnenschein

2002-01-30T23:59:59.000Z

293

Looking for the Top Quark - Virginia State Standards of Learning  

NLE Websites -- All DOE Office Websites (Extended Search)

5 Number and Number Sense - by identifying and representing integers on a number line 7.26 Patterns, Functions and Algebra - by identifying and graphing ordered pairs in the four...

294

Top Quark Pair Production in Early CMS Data  

E-Print Network (OSTI)

from MC truth and the one from control region. In Table 6.5Table 6.3 shows a comparison of two MC results obtained using the direct MC truth andtruth Control region QCD control region V+jets control region Table

Kao, Shih-Chuan

2011-01-01T23:59:59.000Z

295

\\ttbar and single top cross sections at the Tevatron  

SciTech Connect

We present a summary of the latest measurements of the top pair and single top cross sections performed by the CDF and D0 collaborations at the Fermilab Tevatron collider. The Fermilab Tevatron collider ended its run on September 30, 2011 after delivering more than 10 fb{sup -1} of p{bar p} collision data per experiment at {radical}s = 1.96 TeV. A large sample of top quarks collected by the CDF and D0 experiments allows to perform precision measurements of their production which is predicted to occur within the standard model (SM) either in pairs via strong interactions or as single top events via electroweak interactions. Such measurements represent an important test of the theoretical calculations which predict the t{bar t} and single top production cross sections with a precision of 6% to 8% and 5%, respectively. Precise measurements of top pair cross section ({sigma}{sub t{bar t}}) in different t{bar t} final states and single top production via different production mechanisms are highly desirable as they are sensitive to the non-SM particles that may appear in top quark production or decays.

CDF, Elizaveta Shabalina for; collaborations, D0

2012-01-01T23:59:59.000Z

296

Questions and Answers - What kinds of quarks are protons and neutrons made  

NLE Websites -- All DOE Office Websites (Extended Search)

How many quarks are inprotons and neutrons? How many quarks are in<br>protons and neutrons? Previous Question (How many quarks are in protons and neutrons?) Questions and Answers Main Index Next Question (What is the charge of an up quark and of down quark?) What is the charge of an up quarkand of down quark? What kinds of quarks are protons and neutrons made of? What was the old name for the Top and Bottom quark? Protons are made of two Up and one Down quark. The neutron is made of two Down and one Up quark. The Up quarks have a 2/3 positive charge and the Down has a 1/3 negative charge. Fractional charges are a pretty funny concept, but remember we (humans) made up the unit of charge that a proton has, so its very possible that there could be a smaller division of charge. If you add those charges you will see that sum is positive one for the

297

Window For Higgs Boson Mass From Gauge-Higgs Unification  

E-Print Network (OSTI)

We consider six dimensional gauge models compactified on the orbifold T^2/Z_N (N=2,3,4,6) such that the Standard Model (SM) Higgs doublet arises from the extra-dimensional components of the gauge field. For \\Lambda \\leq 10^{19} GeV, where \\Lambda denotes the compactification scale, we obtain 114.4 GeV \\leq m_H \\leq 164 GeV for the SM Higgs boson mass. We also consider gauge-Higgs-top and gauge-Higgs-bottom Yukawa unification which respectively yield m_H = 131^{+4}_{-5} GeV and m_H = 150^{+2}_{-2} GeV for a top quark pole mass M_t =170.9^{+1.8}_{-1.8} GeV. As a special case we recover the result m_H \\leq 132 GeV previously obtained for five dimensional models.

Ilia Gogoladze; Nobuchika Okada; Qaisar Shafi

2007-08-18T23:59:59.000Z

298

Equation of state in hybrid stars and the stability window of quark matter  

E-Print Network (OSTI)

Properties of hybrid stars with a mixed phase composed of asymmetric nuclear matter and strange quark matter are studied. The quark phase is investigated by the quark quasiparticle model with a self-consistent thermodynamic and statistical treatment. We present the stability windows of the strange quark matter with respect to the interaction coupling constant versus the bag constant. We find that the appearance of the quark-hadron mixed phases is associated with the meta-stable or unstable regions of the pure quark matter parameters. The mass-radius relation of the hybrid star is dominated by the equation of state of quark matter rather than nuclear matter. Due to the appearance of mixed phase, the mass of hybrid star is reduced to 1.64 M$_{\\odot}$ with radius 10.6 km by comparison with neutron star.

Xin-Jian Wen

2013-03-09T23:59:59.000Z

299

QuarkNet Stories  

NLE Websites -- All DOE Office Websites (Extended Search)

Technical Workforce Centers at 53 universities and labs 18 HEP experiments 475 high schools in 28 states 60 ,000 students per year The focus of QuarkNet is to involve teachers...

300

QuarkNet Information  

NLE Websites -- All DOE Office Websites (Extended Search)

Beginning its 17th year, QuarkNet involves about 100,000 students from 500+ US high schools with opportunities to: Analyze real data online. Collaborate with students worldwide....

Note: This page contains sample records for the topic "top quark mass" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Quark Loop Contributions to Neutron, Deuteron, and Mercury EDMs from Supersymmetry without R parity  

E-Print Network (OSTI)

We present a detailed analysis of the neutron, deuteron and mercury electric dipole moment from supersymmetry without R parity, focusing on the quark-scalar loop contributions. Being proportional to top Yukawa and top mass, such contributions are often large. Analytical expressions illustrating the explicit role of the R-parity violating parameters are given following perturbative diagonalization of mass-squared matrices for the scalars. Dominant contributions come from the combinations $B_i \\lambda^{\\prime}_{ij1}$ for which we obtain robust bounds. It turns out that neutron and deuteron EDMs receive much stronger contributions than mercury EDM and any null result at the future deuteron EDM experiment or Los Alamos neutron EDM experiment can lead to extra-ordinary constraints on RPV parameter space. Even if R-parity violating couplings are real, CKM phase does induce RPV contribution and for some cases such a contribution is as strong as contribution from phases in the R-parity violating couplings.Hence, we have bounds directly on $|B_i \\lambda^{\\prime}_{ij1}|$ even if the RPV parameters are all real. Interestingly, even if slepton mass and/or $\\mu_0$ is as high as 1 TeV, it still leads to neutron EDM that is an order of magnitude larger than the sensitivity at Los Alamos experiment. Since the results are not much sensitive to $\\tan \\beta$, our constraints will survive even if other observables tighten the constraints on $\\tan \\beta$.

Chan-Chi Chiou; Otto C. W. Kong; Rishikesh D. Vaidya

2007-05-27T23:59:59.000Z

302

Measurement of the Top Quark Pair Production Cross Section in pp Collisions at a Center-of-Mass Energy of 7 TeV with the CMS Experiment at the LHC  

E-Print Network (OSTI)

5 Event Selection and Data Analysis 5.1 Eventdistribution of events in a physics analysis. ROOT Andistribution of events in a physics analysis. http://

Jeng, Geng-yuan

2011-01-01T23:59:59.000Z

303

Quark mixing sum rules and the right unitarity triangle  

E-Print Network (OSTI)

In analogy with the recently proposed lepton mixing sum rules, we derive quark mixing sum rules for the case of hierarchical quark mass matrices with 1-3 texture zeros, in which the separate up and down type 1-3 mixing angles are approximately zero, and $V_{ub}$ is generated from $V_{cb}$ as a result of 1-2 up type quark mixing. Using the sum rules, we discuss the phenomenological viability of such textures, including up to four texture zeros, and show how the right-angled unitarity triangle, i.e., $\\alpha \\approx 90^\\circ$, can be accounted for by a remarkably simple scheme involving real mass matrices apart from a single element being purely imaginary. In the framework of grand unified theories we show how the quark and lepton mixing sum rules may combine to yield an accurate prediction for the reactor angle.

Antusch, Stefan; Malinsky, Michal; Spinrath, Martin

2009-01-01T23:59:59.000Z

304

Quark mixing sum rules and the right unitarity triangle  

E-Print Network (OSTI)

In analogy with the recently proposed lepton mixing sum rules, we derive quark mixing sum rules for the case of hierarchical quark mass matrices with 1-3 texture zeros, in which the separate up and down type 1-3 mixing angles are approximately zero, and $V_{ub}$ is generated from $V_{cb}$ as a result of 1-2 up type quark mixing. Using the sum rules, we discuss the phenomenological viability of such textures, including up to four texture zeros, and show how the right-angled unitarity triangle, i.e., $\\alpha \\approx 90^\\circ$, can be accounted for by a remarkably simple scheme involving real mass matrices apart from a single element being purely imaginary. In the framework of grand unified theories we show how the quark and lepton mixing sum rules may combine to yield an accurate prediction for the reactor angle.

Stefan Antusch; Stephen F. King; Michal Malinsky; Martin Spinrath

2009-10-27T23:59:59.000Z

305

Sample QuarkNet Proposal  

NLE Websites -- All DOE Office Websites (Extended Search)

Department Address: Florida State University Keen Building, City, State: Tallahassee, FL Zip: 32306-4350 Local QuarkNet Leader(s): Local QuarkNet Participants are: Susan Blessing,...

306

Quark-gluon plasma paradox  

E-Print Network (OSTI)

Based on simple physics arguments it is shown that the concept of quark-gluon plasma, a state of matter consisting of uncorrelated quarks, antiquarks, and gluons, has a fundamental problem.

Dariusz Miskowiec

2007-07-06T23:59:59.000Z

307

Quark Matter 2004 Conference Hotel  

NLE Websites -- All DOE Office Websites (Extended Search)

as the conference Hotel. It is adjacent to the Oakland Convention Center where all Quark Matter talks will be held. Quark Matter attendees can get a reduced price of 126...

308

Boson stars: Chemical potential and quark condensates  

E-Print Network (OSTI)

We study the properties of a star made of self-gravitating bosons gas in a mean-field approximation. A generalized set of Tolman-Oppenheimer-Volkov(TOV) equations is derived to incorporate the effect of chemical-potential in the general relativistic frame work. The metric-dependence of the chemical-potential gives a new class of solutions for the boson stars. It is demonstrated that the maximum mass and radius of the star change in a significant way when the effect of finite chemical-potential is considered. We also discuss the case of a boson star made of quark-condensates. It is found that when the self-interaction between the condensates is small as compared to their mass, the typical density is too high to form a diquark-boson star. Our results indicate that the star of quark-condensate may be formed in a low-density and high-pressure regime.

Jitesh R. Bhatt; V. Sreekanth

2009-10-12T23:59:59.000Z

309

Search for stable excited quarks  

Science Conference Proceedings (OSTI)

The possibility of quarks in triality-zero color representations, e.g., 8 or 10, is considered. (GHT)

Baltay, C.; Littenberg, L.; Paige, F.E.

1982-01-01T23:59:59.000Z

310

Heavy quark production in the black hole evaporation at LHC  

SciTech Connect

The understanding of Quantum Chromodynamics (QCD) and Quantum Gravity are currently two of the main open questions in Physics. In order to understand these problems some authors proposed the existence of extra dimensions in the Nature. These extra dimensions would be compacted and not visible on the macroscopic world, but the effects would be manifest in ultrarelativistic colision process. In particular, black holes (BH) could be produced in proton-proton colisions in the Large Hadron Collider (LHC) and in future colliders. The BH is an object characterized by its mass and temperature wich also characterizes the evaporation process. All kind of particle should be produced in this process. Our goal in this contribution is to study the BH production in proton - proton collisions at LHC and its evaporation rate in heavy quarks. We present our estimate considering two scenarios (with and without trapped energy corrections) and compare our predictions with those obtained using perturbative QCD. Our results demonstrate that in both scenarios the charm and bottom production in the BH evaporation are smaller than the QCD prediction at LHC. In contrast, the top production is similar or larger than the QCD prediction, if the trapped energy corrections are disregarded.

Thiel, M.; Goncalves, V. P.; Sauter, W. K. [Instituto de Fisica e Matematica, Universidade Federal de Pelotas (Brazil)

2013-03-25T23:59:59.000Z

311

Nonperturbative enhancement of heavy quark-pair production in a strong SU(2) color field  

Science Conference Proceedings (OSTI)

Nonperturbative charm and bottom quark-pair production is investigated in the early stage of heavy-ion collisions. The time-dependent study is based on a kinetic description of fermion-pair production in strong non-Abelian fields. We introduce a time-dependent chromo-electric external field with a pulselike time evolution to simulate the overlap of two colliding heavy ions. The calculations is performed in a SU(2) color model with finite current quark masses. Yields of heavy quark pairs are compared to the ones of light and strange quark pairs. We show that the small inverse duration time of the field pulse determines the efficiency of the quark-pair production. The expected suppression for heavy quark production, as follows from the Schwinger formula for a constant field, is not seen, but rather an enhanced heavy quark production appears at ultrarelativistic energies.

Levai, Peter; Skokov, Vladimir [KFKI RMKI Research Institute for Particle and Nuclear Physics, P.O. Box 49, Budapest 1525 (Hungary); Gesellschaft fuer Schwerionenforschung mbH, Planckstr. 1, D-64291 Darmstadt (Germany)

2010-10-01T23:59:59.000Z

312

Baryon Spectroscopy and the Constituent Quark Model  

SciTech Connect

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.

A.W. Thomas; R.D. Young

2005-07-26T23:59:59.000Z

313

A Finely-Predicted Higgs Boson Mass from A Finely-Tuned Weak Scale  

E-Print Network (OSTI)

If supersymmetry is broken directly to the Standard Model at energies not very far from the unified scale, the Higgs boson mass lies in the range 128-141 GeV. The end points of this range are tightly determined. Theories with the Higgs boson dominantly in a single supermultiplet predict a mass at the upper edge, (141 \\pm 2) GeV, with the uncertainty dominated by the experimental errors on the top quark mass and the QCD coupling. This edge prediction is remarkably insensitive to the supersymmetry breaking scale and to supersymmetric threshold corrections so that, in a wide class of theories, the theoretical uncertainties are at the level of \\pm 0.4 GeV. A reduction in the uncertainties from the top quark mass and QCD coupling to the level of \\pm 0.3 GeV may be possible at future colliders, increasing the accuracy of the confrontation with theory from 1.4% to 0.4%. Verification of this prediction would provide strong evidence for supersymmetry, broken at a very high scale of ~ 10^{14 \\pm 2} GeV, and also for a Higgs boson that is elementary up to this high scale, implying fine-tuning of the Higgs mass parameter by ~ 20-28 orders of magnitude. Currently, the only known explanation for such fine-tuning is the multiverse.

Lawrence J. Hall; Yasunori Nomura

2009-10-13T23:59:59.000Z

314

Higgs boson masses in supersymmetric models  

SciTech Connect

Imposing supersymmetry on a Higgs potential constrains the parameters that define the potential. In supersymmetric extensions to the stranded model containing only Higgs SU(2){sub L} doublets there exist Higgs boson mass sum rules and bounds on the Higgs masses at tree level. The prescription for renormalizing these sum rules is derived. An explicit calculation is performed in the minimal supersymmetric extension to the standard model (MSSM). In this model at tree level the mass sum rule is M{sub H}{sup 2} + M{sub h}{sup 2} = M{sub A}{sup 2} + M{sub Z}{sup 2}. The results indicate that large corrections to the sum rules may arise from heavy matter fields, e.g. a heavy top quark. Squarks significantly heavier than their fermionic partners contribute large contributions when mixing occurs in the squark sector. These large corrections result from squark-Higgs couplings that become large in this limit. Contributions to individual Higgs boson masses that are quadratic in the squark masses cancel in the sum rule. Thus the naturalness constraint on Higgs boson masses is hidden in the combination of Higgs boson masses that comprise the sum rule. 39 refs., 13 figs.

Berger, M.S.

1991-04-01T23:59:59.000Z

315

A Zip-code for Quarks, Leptons and Higgs Bosons  

E-Print Network (OSTI)

The location of matter fields and the pattern of gauge symmetry in extra dimensions are crucial ingredients for string model building. We analyze realistic MSSM models from the heterotic Z6 Mini-Landscape and extract those properties that are vital for their success. We find that Higgs bosons and the top quark are not localized in extra dimensions and live in the full D=10 dimensional space-time. The first two families of quarks and leptons, however, live at specific fixed points in extra dimensional space and exhibit a (discrete) family symmetry. Within a newly constructed Z2XZ4 orbifold framework we further elaborate on these location properties and the appearance of discrete symmetries. A similar geometrical picture emerges. This particular Zip-code for quarks, leptons and Higgs bosons seems to be of more general validity and thus a useful guideline for realistic model building in string theory.

Damian Kaloni Mayorga Pena; Hans Peter Nilles; Paul-Konstantin Oehlmann

2012-09-26T23:59:59.000Z

316

Dirac Type Gauge Theories and the Mass of the Higgs Boson  

E-Print Network (OSTI)

We discuss the mass of the (physical component of the) Higgs boson in one-loop and top-quark mass approximation. For this the minimal Standard Model is regarded as a specific (parameterized) gauge theory of Dirac type. It is shown that the latter formulation, in contrast to the usual description of the Standard Model, gives a definite value for the Higgs mass. The predicted value for the Higgs mass depends on the value addressed to the top mass m_T. We obtain m_H= 186 \\pm 8 GeV for m_T = 174 \\pm 3 GeV (direct observation of top events), resp. m_H = 184 \\pm 22 GeV for m_T = 172 \\pm 10 GeV (Standard Model electroweak fit). Although the Higgs mass is predicted to be near the upper bound, m_H is in full accordance with the range 114 \\leq m_H < 193 GeV that is allowed by the Standard Model. We show that the inclusion of (Dirac) massive neutrinos does not alter the results presented. We also briefly discuss how the derived mass values are related to those obtained within the frame of non-commutative geometry.

Juergen Tolksdorf; Torsten Thumstaedter

2006-02-12T23:59:59.000Z

317

Single-top hadroproduction in association with a W boson.  

E-Print Network (OSTI)

of the perturbative momentum scale). Furthermore, effects of physics beyond the Standard Model are thought to lie around 1 the electroweak scale, thus the top quark sector provides a valuable window for new physics. A useful process to study in this regard... quark attached to the Wt vertex as a b, implicitly representing any CKM-allowed down-type quark. It is convenient to introduce the following invariants s = (p1+p2)2, t1 = t?m2t = (k1?p1)2?m2t , u1 = u?m2t = (k2?p1)2?m2t (3.2) such that s + t1 + u1 = m2W...

Frixione, Stefano; Laenen, Eric; Motylinski, Patrick; Webber, Bryan R; White, C D

318

Hadron Mass Extraction from Lattice QCD  

E-Print Network (OSTI)

The extraction of quantities from lattice QCD calculations at realistic quark masses is of considerable importance. Whilst physical quark masses are some way off, the recent advances in the calculation of hadron masses within full QCD now invite improved extrapolation methods. We show that, provided the correct chiral behaviour of QCD is respected in the extrapolation to realistic quark masses, one can indeed obtain a fairly reliable determination of masses, the sigma commutator and the J parameter. We summarise these findings by presenting the nonanalytic behaviour of nucleon and rho masses in the standard Edinburgh plot.

S. V. Wright; D. B. Leinweber; A. W. Thomas; K. Tsushima

2001-11-27T23:59:59.000Z

319

A handbook of vector-like quarks: mixing and single production  

E-Print Network (OSTI)

We obtain constraints on the mixing of vector-like quarks coupling predominantly to the third generation. We consider all (seven) relevant types of vector-like quarks, individually. The constraints are derived from oblique corrections and Z -> b bbar measurements at LEP and SLC. We investigate the implications of these constraints on LHC phenomenology, concerning the decays of the heavy quarks and their single production. We also explore indirect effects of heavy quark mixing in top and bottom couplings. A remarkable effect is the possibility of explaining the anomalous forward-backward asymmetry in Z -> b bbar at LEP, with a hypercharge -5/6 doublet. We also study the impact of the new quarks on single Higgs production at the LHC and Higgs decay.

J. A. Aguilar-Saavedra; R. Benbrik; S. Heinemeyer; M. Perez-Victoria

2013-06-03T23:59:59.000Z

320

A handbook of vector-like quarks: mixing and single production  

E-Print Network (OSTI)

We obtain constraints on the mixing of vector-like quarks coupling predominantly to the third generation. We consider all (seven) possible types of vector-like quarks, individually. The constraints are derived from oblique corrections and Z -> b bbar measurements at LEP and SLC. We investigate the implications of these constraints on LHC phenomenology, concerning the decays of the heavy quarks and their single production. We also explore indirect effects of heavy quark mixing in top and bottom couplings. The most remarkable of these effects is the possibility of explaining the anomalous forward-backward asymmetry in Z -> b bbar at LEP, with a hypercharge -5/6 doublet. We also study the impact of the new quarks on single Higgs production at the LHC and Higgs decay.

J. A. Aguilar-Saavedra; R. Benbrik; S. Heinemeyer; M. Perez-Victoria

2013-06-03T23:59:59.000Z

Note: This page contains sample records for the topic "top quark mass" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Color superconductivity with determinant interaction in strange quark matter  

E-Print Network (OSTI)

We investigate the effect of six fermion determinant interaction on color superconductivity as well as on chiral symmetry breaking. Coupled mass gap equations and the superconducting gap equation are derived through the minimisation of the thermodynamic potential. The effect of nonzero quark -- antiquark condensates on the superconducting gap is derived. This becomes particularly relevant for the case of 2-flavor superconducting matter with unpaired strange quarks in the diquark channel. While the effect of six fermion interaction leads to an enhancement of u-d superconductivity, due to nonvanishing strange quark--antiquark condensates, such an enhancement will be absent at higher densities for u-s or d-s superconductivity due to early (almost) vanishing of light quark-- antiquark condensates.

Amruta Mishra; Hiranmaya Mishra

2006-05-21T23:59:59.000Z

322

Hausdorff dimension of quark trajectories from SCSB and confinement  

Science Conference Proceedings (OSTI)

The quark condensate is calculated using the effective-action formalism, by imposing an ansatz for the Wilson loop, which interpolates between the area-law for large loops and the area-squared law for small loops. For 3 colors and 2 light flavors, a lower bound of 460 MeV for the constituent quark mass is found to be accessible, provided an effective scale-dependent string tension of a light quark falls off linearly with the Schwinger proper time. This behavior of the effective string tension yields the Hausdorff dimension of a light-quark trajectory equal to 4, which shows that these trajectories are similar to branched polymers. A gluonic chain based on such trajectories provides an example of a model describing weak first-order deconfinement phase transition, which takes place in SU(3) Yang-Mills theory.

Antonov, D.; Ribeiro, J. E. F. T. [Departamento de Fisica and Centro de Fisica das Interaccoes Fundamentais, Instituto Superior Tecnico, UT Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)

2011-05-23T23:59:59.000Z

323

A measurement of the top pair production cross-section in the dilepton channel using lepton plus track selection  

Science Conference Proceedings (OSTI)

Using 1.1 fb{sup -1} of data collected by the Collider Detector at Fermilab (CDF) from Run II of the Fermilab Tevatron, they measure the t{bar t} production cross section in events with two leptons, significant missing transverse energy, and {ge} 2 jets. As the Run II dataset grows, more stringent tests of Standard Model predictions for the top quark sector are becoming possible. The dilepton channel, where both top quarks decay t {yields} Wb {yields} {ell}{nu}b, is of particular interest due to its high purity even in the absence of a b jet 'tagging' requirement. Use of an isolated track as the second lepton significant increases the dilepton acceptance, at the price of some increase in background, particular from W + jets events where one of the jets is identified as a lepton. With the amount of data available, it has been possible to improve the estimate of the contribution from that background, reflected in a reduced systematic uncertainty. Assuming a branching ratio of BR(W {yields} {ell}{nu}) = 10.8% and a top mass of m{sub t} = 175 GeV/c{sup 2}, the measured cross-section is {sigma}(p{bar p} {yields} t{bar t}) = 8.3 {+-} 1.3(stat.) {+-} 0.7(syst.) {+-} 0.5(lumi.) pb. The result is consistent with the Standard Model prediction of 6.7{sub -0.9}{sup +0.7} pb and represents a significant improvement in precision over previous results using this selection.

Mills, Corrinne Elaine; /UC, Santa Barbara

2007-06-01T23:59:59.000Z

324

Higgs boson mass and new physics  

E-Print Network (OSTI)

We discuss the lower Higgs boson mass bounds which come from the absolute stability of the Standard Model (SM) vacuum and from the Higgs inflation, as well as the prediction of the Higgs boson mass coming from asymptotic safety of the SM. We account for the 3-loop renormalization group evolution of the couplings of the Standard Model and for a part of two-loop corrections that involve the QCD coupling alpha_s to initial conditions for their running. This is one step above the current state of the art procedure ("one-loop matching--two-loop running"). This results in reduction of the theoretical uncertainties in the Higgs boson mass bounds and predictions, associated with the Standard Model physics, to 1-2 GeV. We find that with the account of existing experimental uncertainties in the mass of the top quark and alpha_s (taken at 2sigma level) the bound reads M_H>=M_min (equality corresponds to the asymptotic safety prediction), where M_min=129+-6 GeV. We argue that the discovery of the SM Higgs boson in this range would be in agreement with the hypothesis of the absence of new energy scales between the Fermi and Planck scales, whereas the coincidence of M_H with M_min would suggest that the electroweak scale is determined by Planck physics. In order to clarify the relation between the Fermi and Planck scale a construction of an electron-positron or muon collider with a center of mass energy ~200+200 GeV (Higgs and t-quark factory) would be needed.

Fedor Bezrukov; Mikhail Yu. Kalmykov; Bernd A. Kniehl; Mikhail Shaposhnikov

2012-05-13T23:59:59.000Z

325

Heavy-quark free energy at finite temperature with 2+1 flavors of improved Wilson quarks in fixed scale approach  

E-Print Network (OSTI)

The free energy between a static quark and an antiquark is studied by using the color-singlet Polyakov-line correlation at finite temperature. We perform simulations on $32^3 \\times 12$, 10, 8, 6, 4 lattices in the high temperature phase with the RG-improved gluon action and 2+1 flavors of the clover-improved Wilson quark action. Since the simulations are based on the fixed scale approach that the temperature can be varied without changing the spatial volume and renormalization factor, it is possible to investigate temperature dependence of the heavy-quark free energy without any adjustment of the overall constant. We find that, the heavy-quark free energies at short distance converge to the heavy-quark potential evaluated from the Wilson-loop operator at zero temperature, in accordance with the expected insensitivity of short distance physics to the temperature. At long distance, the heavy-quark free energies approach to twice the single-quark free energies, implying that the interaction between heavy quarks is screened. The Debye screening mass obtained from the long range behavior of the heavy-quark free energy is compared with results of the thermal perturbation theory and those of $N_f=2$ and $N_f=0$ lattice simulations.

Y. Maezawa; S. Aoki; S. Ejiri; T. Hatsuda; K. Kanaya; H. Ohno; T. Umeda

2009-11-02T23:59:59.000Z

326

CERN-PH-TH/2006-198 QCD with light Wilson quarks on fine lattices (I): first experiences and physics results  

E-Print Network (OSTI)

Recent conceptual, algorithmic and technical advances allow numerical simulations of lattice QCD with Wilson quarks to be performed at significantly smaller quark masses than was possible before. Here we report on simulations of two-flavour QCD at sea-quark masses from slightly above to approximately 1/4 of the strange-quark mass, on lattices with up to 64×32 3 points and spacings from 0.05 to 0.08 fm. Physical sea-quark effects are clearly seen on these lattices, while the lattice effects appear to be quite small, even without O(a) improvement. A striking result is that the dependence of the pion mass on the sea-quark mass is accurately described by leading-order chiral perturbation theory up to meson masses of about 500 MeV. 1.

L. Del Debbio; L. Giusti; M. Lüscher; R. Petronzio; N. Tantalo

2006-01-01T23:59:59.000Z

327

edited1_QuarkWorkbench  

NLE Websites -- All DOE Office Websites (Extended Search)

QUARK WORKBENCH TEACHER NOTES DESCRIPTION Students use cleverly constructed puzzle pieces and look for patterns in how those pieces can fit together. The puzzles pieces obey, as...

328

Revealing dressed-quarks via the proton's charge distribution  

E-Print Network (OSTI)

The proton is arguably the most fundamental of Nature's readily detectable building blocks. It is at the heart of every nucleus and has never been observed to decay. It is nevertheless a composite object, defined by its valence-quark content: u+u+d -- i.e., two up (u) quarks and one down (d) quark; and the manner by which they influence, inter alia, the distribution of charge and magnetisation within this bound-state. Much of novelty has recently been learnt about these distributions; and it now appears possible that the proton's momentum-space charge distribution possesses a zero. Experiments in the coming decade should answer critical questions posed by this and related advances; and we explain how such new information may assist in charting the origin and impact of key emergent phenomena within the strong interaction. Specifically, we show that the possible existence and location of a zero in the proton's electric form factor are a measure of nonperturbative features of the quark-quark interaction in the Standard Model, with particular sensitivity to the running of the dressed-quark mass.

Ian C. Cloet; Craig D. Roberts; Anthony W. Thomas

2013-04-03T23:59:59.000Z

329

Thermalization of heavy quarks in the quark-gluon plasma  

E-Print Network (OSTI)

Charm- and bottom-quark rescattering in a quark-gluon plasma (QGP) is investigated with the objective of assessing the approach toward thermalization. Employing a Fokker-Planck equation to approximate the collision integral of the Boltzmann equation we augment earlier studies based on perturbative parton cross sections by introducing resonant heavy-light quark interactions. The latter are motivated by recent QCD lattice calculations that indicate the presence of "hadronic" states in the QGP. We model these states by colorless (pseudo-) scalar and (axial-) vector D and B mesons within a heavy-quark effective theory framework. We find that the presence of these resonances at moderate QGP temperatures substantially accelerates the kinetic equilibration of c quarks as compared to using perturbative interactions. We also comment on consequences for D-meson observables in ultrarelativistic heavy-ion collisions.

van Hees, H.; Rapp, Ralf.

2005-01-01T23:59:59.000Z

330

QCD based static potential between heavy quarks  

SciTech Connect

We calculate the static potential between a quark-anti quark pair using dual potentials to describe long-distance Yang-Mills theory.

Baker, M. [Washington Univ., Seattle, WA (United States). Dept. of Physics; Ball, J.S. [Utah Univ., Salt Lake City, UT (United States). Dept. of Physics; Zachriasen, R. [California Inst. of Tech., Pasadena, CA (United States)

1991-12-31T23:59:59.000Z

331

Physics at the 100 GeV mass scale: Proceedings  

Science Conference Proceedings (OSTI)

This report contains the following papers: heavy quarks--experimental; the theory of heavy flavour production; precision experiments in electroweak interactions; theory of precision electroweak measurements; applications of QCD to hadron-hadron collisions; W{sup +}W{sup {minus}} interactions and the search for the Higgs Boson; electroweak symmetry breaking: Higgs/Whatever; electron-positron storage rings as heavy quark factories; prospects for next-generation e{sup +}e{sup {minus}} linear colliders; current prospects for hadron colliders; hadron colliders beyond the SSC; recent results on weak decays of charmed mesons from the Mark 3 experiment; recent CLEO results on bottom and charm; recent results on B-decays from ARGUE; a review of recent results on the hadron and photoproduction of charm; search for the top quark at UA1; recent results from the UA2 experiment at the CERN {bar p}p collider; selected preliminary results from CDF; new measurement of the phase difference {Phi}{sub 00} {minus} {Phi}{sub {plus minus}} in CP--violating K{sup 0} decays; a recent result on CP violation by E731 at Fermilab; rare kaon decay experiments; CP violation; inverse muon decay, neutrino dimuon production, and a search for neutral heavy leptons at the tevatron; first results from MACRO; a superstring theory underview; recent results from TRISTAN ; measurements of the Z boson resonance parameters at SLC; decays of the Z boson; and theory--weak neutral currents and the Z mass after the SLC.

Brennan, E.C. (ed.)

1990-01-01T23:59:59.000Z

332

Potential energy for quarks  

SciTech Connect

It is argued on theoretical and phenomenological grounds that confinement of quarks is intrinsically a many-body interaction. The Born-Oppenheimer approximation to the bag model is shown to give rise to a static potential energy that consists of a sum of two-body Coulomb terms and a many-body confining term. Following the success of this potential in heavy Q anti Q systems it is being applied to Q/sup 2/ anti Q/sup 2/. Preliminary calculations suggest that dimeson bound states with exotic flavor, such as bb anti s anti s, exist. 13 refs., 5 figs.

Heller, L.

1985-01-01T23:59:59.000Z

333

Quark confinement and hadronic interactions  

SciTech Connect

A study of quark models for many-hadron systems is presented. The starting point in the construction of these nonrelativistic models is a proper formal definition of the concept of color singlet and nonsinglet clusters in a multiquark system which respects the exchange symmetry of the quarks. This definition provides a natural way to impose saturation of the confining forces.

Lenz, F.; Londergan, J.T.; Moniz, E.J.; Rosenfelder, R.; Stingl, M.; Yazaki, K.

1986-08-01T23:59:59.000Z

334

Effects of color superconductivity on the nucleation of quark matter in neutron stars  

E-Print Network (OSTI)

We study the nucleation of quark matter drops at the center of cold deleptonized neutron stars. This is relevant in the determination of the critical mass $M_{cr}$ of hadronic stars above which it is possible a transition to a quark star (strange or hybrid). We investigate the dependence of $M_{cr}$ upon the parameters of the quark model (the Bag constant $B$, the pairing gap $\\Delta$, and the surface tension $\\sigma$ of the quark-hadron interphase) and for different parametrization of the hadronic equations of state. The dependence of $M_{cr}$ on $B$, $\\Delta$ and $\\sigma$ is mild if the parameters of the quark model correspond to hybrid stars, and strong if they correspond to strange stars. For a large part of the parameter space corresponding to hybrid stars, the critical mass is very close (but smaller than) the maximum mass of hadronic stars, and therefore compatible with a "mixed" population of compact stars (pure hadronic up to the critical mass and hybrid above the critical mass). For very large $B$ the critical mass is never smaller than the maximum mass of hadronic stars, implying that quark stars cannot form through the here studied mechanism. The energy released in the conversion is $3 \\times 10^{52}$ erg - $4 \\times 10^{53}$ erg, i.e. sufficient to power a gamma ray burst.

I. Bombaci; G. Lugones; I. Vidana

2006-03-23T23:59:59.000Z

335

Excited quark production at a 100 TeV VLHC  

E-Print Network (OSTI)

I look for a dijet resonance produced by an excited quark q* in a simulated sample corresponding to 3 ab^{-1} of pp collisions at $\\sqrt{s} = 100$ TeV. Using a cut and count analysis approach I demonstrate the potential to explore q* masses up to 50 TeV, corresponding to a length scale of around 4 am.

Jacob Anderson

2013-09-03T23:59:59.000Z

336

Excited quark production at a 100 TeV VLHC  

E-Print Network (OSTI)

I look for a dijet resonance produced by an excited quark q* in a simulated sample corresponding to 3 ab^{-1} of pp collisions at $\\sqrt{s} = 100$ TeV. Using a cut and count analysis approach I am able to explore q* masses up to 50 TeV, corresponding to a length scale of around 4 am.

Anderson, Jacob

2013-01-01T23:59:59.000Z

337

Phase transitions in quark matter under strong magnetic fields  

SciTech Connect

In this work we use de SU(2) Nambu-Jona-Lasinio model to study the chiral transition at finite temperature, chemical potential and magnetic field. We show how the magnetic field affects the location of the critical end-point in the phase diagram, the constituent quark masses and the spinodal lines concerning the first order transition.

Garcia, Andre F.; Pinto, Marcus B. [Physics Department, Universidade Federal de Santa Catarina (Brazil)

2013-03-25T23:59:59.000Z

338

Quark helicity flip generalized parton distributions from two-flavor lattice QCD  

E-Print Network (OSTI)

We present an initiatory study of quark helicity flip generalized parton distributions (GPDs) in n_f=2 lattice QCD, based on clover-improved Wilson fermions for a large number of coupling constants and pion masses. Quark helicity flip GPDs yield essential information on the transverse spin structure of the nucleon. In this work, we show first results on their lowest moments and dipole masses and study the corresponding chiral and continuum extrapolations.

M. Gockeler; Ph. Hagler; R. Horsley; D. Pleiter; P. E. L. Rakow; A. Schafer; G. Schierholz; J. M. Zanotti

2005-07-01T23:59:59.000Z

339

Top Ten Lists  

NLE Websites -- All DOE Office Websites (Extended Search)

Fueleconomy Top Ten Fueleconomy Top Ten EPA Rated - 2014 EPA Rated - All Years Shared Estimates - All Years Misconceptions Fueleconomy.gov's Top Ten EPA-Rated Fuel Sippers (2014) Include all-electric and plug-in hybrid vehicles? Yes No Vehicles are ranked by their combined rating (weighted by 55% city and 45% highway). In the event of a tie, multiple vehicles may share the same ranking. Electric vehicles are measured in Miles Per Gallon equivalent (MPGe) where 33.7 kW-hrs = 1 gallon of gasoline. 1. 2014 Chevrolet Spark EV 2014 Chevrolet Spark EV Combined 119 City 128/Highway 109 All-electric, Auto (A1) 2. 2014 Honda Fit EV 2014 Honda Fit EV Combined 118 City 132/Highway 105 All-electric, Auto (A1) 3. 2014 Fiat 500e 2014 Fiat 500e Combined 116 City 122/Highway 108 All-electric, Auto (A1)

340

Matching the quark model to the 1/N{sub c} expansion  

Science Conference Proceedings (OSTI)

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 behind the fitted coefficients for the scalar part of the most general two-body quark-quark interaction. We find that both pion exchange and gluon exchange lead to the dominance of the same operator at the level of the effective mass operator, which is also observed from data.

Pirjol, Dan [National Institute for Physics and Nuclear Engineering, Department of Particle Physics, 077125 Bucharest (Romania); Schat, Carlos [Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701 (United States) and Departamento de Fisica, FCEyN, Universidad de Buenos Aires, Ciudad Universitaria, Pab.1, (1428) Buenos Aires (Argentina)

2011-10-24T23:59:59.000Z

Note: This page contains sample records for the topic "top quark mass" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Charge Asymmetry in Top Pair plus Jet Production -- A Snowmass White Paper  

E-Print Network (OSTI)

We investigate the discovery potential of the top-quark charge asymmetry at the LHC in top-antitop production in association with a hard jet. In this process, the charge asymmetry can be accessed via two novel observables: the incline asymmetry, which probes the quark-antiquark channel, and the energy asymmetry, which gives access to the quark-gluon channel. At 8 TeV collision energy, the significance for both observables is statistically limited. With 14 TeV and an integrated luminosity of 50 inverse fb or more, an asymmetry of up to -12% can be observed with a statistical significance of more than 5 standard deviations. Prospects of measuring the charge asymmetry at the intended high-luminosity and high-energy LHC upgrades are discussed.

Stefan Berge; Susanne Westhoff

2013-07-23T23:59:59.000Z

342

Active QuarkNet Centers  

NLE Websites -- All DOE Office Websites (Extended Search)

Active QuarkNet Centers Active QuarkNet Centers       QuarkNet Home - Information - Calendar - Contacts - Projects - Forms: EoI - Teachers Centers on a Google Map @ the PTEC website Mentor List Sorted by: Last Name Institution Name First Year in Program Argonne National Laboratory - On sabbatical Black Hills State University Brown, Northeastern & Brandeis Universities Brookhaven National Laboratory, Columbia & Stony Brook Universities Chicago State University Colorado State University Fermilab & University of Chicago Florida Institute of Technology Florida International University Florida State University Hampton, George Mason, William & Mary Universities Idaho State University Indiana University - On sabbatical Johns Hopkins University

343

Density-Dependent Relations among Properties of Hadronic Matter and Applications to Hadron-Quark Stars  

SciTech Connect

Density-dependent relations among the saturation properties of symmetric nuclear matter and hyperonic matter, and properties of hadron-(strange) quark stars are shown by applying the conserving nonlinear {sigma}-{omega}-{rho} hadronic mean-field theory. Nonlinear interactions are renormalized self-consistently as effective coupling constants, effective masses, and sources of equations of motion by maintaining thermodynamic consistency to the mean-field approximation. Effective masses and coupling constants at the saturation point of symmetric nuclear matter simultaneously determine the binding energy and saturation properties of hyperonic matter. The coupling constants expected from the hadronic mean-field model and SU(6) quark model for the vector coupling constants are compared by calculating masses of hadron-quark neutron stars. The nonlinear {sigma}-{omega}-{rho} mean-field approximation with vacuum fluctuation corrections and strange quark matter defined by the MIT-bag model were employed to examine properties of hadron-(strange) quark stars. We found that hadron-(strange) quark stars become more stable at high densities compared to pure hadronic and strange quark stars.

Uechi, Hiroshi [Department of Distributions and Communication Sciences, Osaka Gakuin University, Osaka (Japan); Uechi, Schun T. [Research Center for Nuclear Physics (RCNP), Osaka University, Osaka (Japan)

2011-05-06T23:59:59.000Z

344

Non-leptonic decays in an extended chiral quark model  

Science Conference Proceedings (OSTI)

We consider the color suppressed (nonfactorizable) amplitude for the decay mode B{sub d}{sup 0}{yields}{pi}{sup 0}{pi}{sup 0}. We treat the b-quark in the heavy quark limit and the energetic light (u,d,s) quarks within a variant of Large Energy Effective Theory combined with an extension of chiral quark models. Our calculated amplitude for B{sub d}{sup 0}{yields}{pi}{sup 0}{pi}{sup 0} is suppressed by a factor of order {Lambda}{sub QCD}/m{sub b} with respect to the factorized amplitude, as it should according to QCD-factorization. Further, for reasonable values of the (model dependent) gluon condensate and the constituent quark mass, the calculated nonfactorizable amplitude for B{sub d}{sup 0}{yields}{pi}{sup 0}{pi}{sup 0} can easily accomodate the experimental value. Unfortunately, the color suppressed amplitude is very sensitive to the values of these model dependent parameters. Therefore fine-tuning is necessary in order to obtain an amplitude compatible with the experimental result for B{sub d}{sup 0}{yields}{pi}{sup 0}{pi}{sup 0}.

Eeg, J. O. [Dept. of Physics, Univ. of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo (Norway)

2012-10-23T23:59:59.000Z

345

QuarkNet - Educational Materials  

NLE Websites -- All DOE Office Websites (Extended Search)

2 | Projects | Educational Materials Resources for Teachers This year's QuarkNet teachers compiled a list of files and links that can be used as classroom resources and lesson plan...

346

QuarkNet Boot Camp  

NLE Websites -- All DOE Office Websites (Extended Search)

Overview Memo Milestones Resources Schedule To: All QuarkNet collaborators From: Tom Jordan Date: 18 July 2011 Re: Testing and analysis of early data As you know, CMS has been...

347

Classical Quark Models: An Introduction  

E-Print Network (OSTI)

We present an elementary introduction to some of the quark models used to understand the properties of light mesons and baryons. These lectures are intended for both theoretical and experimental graduate students beginning their study of the strong interaction.

A. W. Thomas; S. V. Wright

1998-08-04T23:59:59.000Z

348

Category:Top level | Open Energy Information  

Open Energy Info (EERE)

View form View form View New Pages Recent Changes All Special Pages Semantic Search/Querying Get Involved Help Apps Datasets Community Login | Sign Up Search Category Facebook icon Twitter icon » Category:Top level Jump to: navigation, search This page has been deleted. The deletion and move log for the page are provided below for reference. 16:11, 16 August 2012 Rmckeel (Talk | contribs) deleted page Category:Top level (Mass removal of pages added by Fceeh) There is currently no text in this page. You can search for this page title in other pages, or search the related logs, but you do not have permission to create this page. Subcategories This category has only the following subcategory. H [×] Help‎ 68 pages Retrieved from "http://en.openei.org/wiki/Category:Top_level"

349

The Higgs Boson Might Not Couple To B Quarks.  

E-Print Network (OSTI)

We discuss an alternative version of the electroweak standard model, in which only the heavy t quark, not the light fermions, couples to the Higgs boson with a strength given by the standard model. The Higgs particle decays dominantly into two gluons jets. The branching ratio for the 2? decay is about 3.5%. The Higgs particle would be a narrow object (width about 60 KeV), and its mass might be consistent with the value given by typical estimates of radiative effects measured by the LEP experiments. to appear in Physics Letters B.As far as the mass generation within the framework of the standard electroweak model is concerned, one must differentiate between the mass generation for the electroweak bosons W, Z, the mass generation for the heavy t quark, and the generation of mass for the leptons and the five remaining, relatively light quarks. While there exists no freedom in the choice of the interaction strengths of the weak bosons with the scalar field, which is dictated

Xavier Calmet; Harald Fritzsch

2008-01-01T23:59:59.000Z

350

Advances in Quark Gluon Plasma  

E-Print Network (OSTI)

In the last 20 years, heavy-ion collisions have been a unique way to study the hadronic matter in the laboratory. Its phase diagram remains unknown, although many experimental and theoretical studies have been undertaken in the last decades. The Relativistic Heavy Ion Collider (RHIC) at BNL was the first ever built heavy-ion collider. RHIC delivered its first collisions in June 2000 boosting the heavy-ion community. Impressive amount of experimental results has been obtained. In November 2010, the Large Hadron Collider (LHC) at CERN delivered lead-lead collisions at unprecedented center-of-mass energies, 14 times larger than that at RHIC. Needless to say that the heavy-ion programs at RHIC and LHC promise fascinating and exciting results in the next decade. In the second part, a historical approach will be adopted, starting with the notion of limiting temperature of matter introduced by Hagedorn in the 60's and the discovery of the QCD asymptotic freedom in the 70's. The phase diagram of hadronic matter, conceived as nowadays, will be shown together with the most important predictions of lattice QCD calculations at finite temperature. In the third part, the heavy-ion collisions at ultra-relativistic energies will be proposed as a unique experimental method to study QGP in the laboratory, as suggested by the Bjorken model. In the last part of these lectures, I will present my biased review of the numerous experimental results obtained in the last decade at RHIC which lead to the concept of strong interacting QGP, and the first results obtained at LHC with the 2010 and 2011 PbPb runs. Finally, the last section is devoted to refer to other lectures about quark gluon plasma and heavy ion physics.

Gines Martinez

2013-04-04T23:59:59.000Z

351

WIPP Receives Top Safety Award  

NLE Websites -- All DOE Office Websites (Extended Search)

WIPP Receives Top Safety Award CARLSBAD, N.M., November 10, 2011 - The U.S. Department of Energy's (DOE) Waste Isolation Pilot Plant (WIPP) received top accolades from New...

352

Static-light meson masses from twisted mass lattice QCD  

E-Print Network (OSTI)

We compute the static-light meson spectrum using two-flavor Wilson twisted mass lattice QCD. We have considered five different values for the light quark mass corresponding to 300 MeV < m_PS < 600 MeV. We have extrapolated our results, to make predictions regarding the spectrum of B and B_s mesons.

ETM Collaboration; Karl Jansen; Chris Michael; Andrea Shindler; Marc Wagner

2008-08-15T23:59:59.000Z

353

Composition and stability of hybrid stars with hyperons and quark color-superconductivity  

E-Print Network (OSTI)

The recent measurement of 1.97 solar mass pulsar places a stringent lower bound on the maximum mass of compact stars and thus challenges the existence of any agents which soften the equation of state of ultra-dense matter. We address the question whether hyperons and/or quark matter can be accommodated in massive compact stars by constructing an equation of state based on a combination of phenomenological relativistic hyper-nuclear density functional and an effective model of QCD (the Nambu-Jona-Lasinio model). Stable configurations are obtained with M < 1.97M_{\\sun} featuring hyper-nuclear and quark matter in color superconducting state if the equation of state of nuclear matter is stiff above the saturation density, the transition to quark matter takes place at a few times the nuclear saturation density, and the repulsive vector interactions in quark matter are substantial.

Bonanno, Luca

2011-01-01T23:59:59.000Z

354

Yukawaon Model with Anomaly Free Set of Quarks and Leptons in a U(3) Family Symmetry  

E-Print Network (OSTI)

In the so-called "yukawaon" model, the (effective) Yukawa coupling constants $Y_f^{eff}$ are given by vacuum expectation values (VEVs) of scalars $Y_f$ (yukawaons) with $3\\times 3$ components. So far, yukawaons $Y_f$ have been assigned to ${\\bf 6}$ or ${\\bf 6}^*$ of U(3) family symmetry, so that quarks and leptons were not anomaly free in U(3). In this paper, yukawaons are assigned to ${\\bf 8}+{\\bf 1}$ of U(3), so that quarks and leptons are anomaly free. Since VEV relations among yukawaons are also considerably changed, parameter fitting of the model is renewed. After fixing our free parameters by observed mass ratios, we have only two and one remaining free parameters for quark and lepton mixings, respectively. We obtain successful predictions for the quark and lepton mixing parameters including magnitudes of $CP$ violation. The effective Majorana neutrino mass is also predicted.

Yoshio Koide; Hiroyuki Nishiura

2013-08-09T23:59:59.000Z

355

Measurement of b-quark Jet Shapes at CDF  

SciTech Connect

The main topic of this thesis is the measurement of b-quark jet shapes at CDF. CDF is an experiment located at Fermilab, in the United States, which studies proton-antiproton collisions at a center of mass energy of 1.96TeV. To reach this energy, the particles are accelerated using the Tevatron accelerator which is currently the highest energy collider in operation. The data used for this analysis were taken between February 2002 and September 2004 and represent an integrated luminosity of about 300 pb{sup -1}. This is the first time that b-quark jet shapes have been measured at hadron colliders. The basis of this measurement lies in the possibility of enhancing the b-quark jet content of jet samples by requiring the jets to be identified as having a displaced vertex inside the jet cone. Such jets are called tagged. This enhances the b-quark jet fraction from about 5% before tagging to 20-40% after tagging, depending on the transverse momentum of the jets. I verified that it is possible to apply this secondary vertex tagging algorithm to different cone jet algorithms (MidPoint and JetClu) and different cone sizes (0.4 and 0.7). I found that the performance of the algorithm does not change significantly, as long as the sub-cone inside which tracks are considered for the tagging is kept at the default value of 0.4. Because the b-quark purity of the jets is still relatively low, it is necessary to extract the shapes of b-quark jets in a statistical manner from the jet shapes both before and after tagging. The other parameters that enter into the unfolding equation used to extract the b-quark jet shapes are the b-jet purities, the biases due to the tagging requirement both for b- and nonbjets and the hadron level corrections. The last of these terms corrects the measured b-jet shapes back to the shapes expected at hadron level which makes comparisons with theoretical models and other experimental results possible. This measurement shows that, despite relatively large systematic uncertainties, the measured b-quark jet shapes are significantly different from those expected from the so-called Pythia Tune A Monte Carlo simulation, the most widely used Leading Order Monte Carlo model at CDF. This difference can be mostly attributed to the fact that the fraction of b-quark jets that originate from flavour creation (where a single b-quark is expected inside the same jet cone) over those that originate from gluon splitting (where two b-quarks are expected to be inside the same jet cone) is slightly different in the Pythia Tune A Monte Carlo predictions than in data. This measurement can help in the tuning of the fraction of gluon splitting to flavour creation b-quark jets in the Monte Carlo simulation. This tuning is particularly important for the extrapolation up to LHC energies where many searches will involve b-quark jets. During the first year of my thesis work, I worked on the implementation of a prototype detector control system for the electromagnetic calorimeter which is being built for the CMS experiment at CERN. The prototype which I implemented was used to monitor and control the high voltage, low voltage, cooling and precision temperature monitoring systems during the summer 2003 test-beam. This was one of the first, almost complete, systems implemented and used by an LHC experiment for test-beam monitoring.

Lister, Alison; /Zurich, ETH

2006-03-01T23:59:59.000Z

356

Heavy Quark Physics in Nf = 2 QCD ? CP-PACS Collaboration:  

E-Print Network (OSTI)

We present a preliminary analysis of the heavy-heavy spectrum and heavy-light decay constants in full QCD, using a tadpole-improved SW quark action and an RG-improved gauge action on a 16 3 × 32 lattice with four sea quark masses corresponding to m?/m? ? 0.8, 0.75, 0.7, 0.6 and a ?1 ? 1.3 GeV. We focus particularly on the effect of sea quarks on these observables. 1.

unknown authors

1998-01-01T23:59:59.000Z

357

An estimate of heavy quark momentum diffusion coefficient in gluon plasma  

E-Print Network (OSTI)

We calculate the momentum diffusion coefficient for heavy quarks in SU(3) gluon plasma at temperatures 1-2 times the deconfinement temperature. The momentum diffusion coefficient is extracted from a Monte Carlo calculation of the correlation function of color electric fields, in the leading order of expansion in heavy quark mass. Systematics of the calculation are examined, and compared with perturbtion theory and other estimates.

Debasish Banerjee; Saumen Datta; Rajiv V. Gavai; Pushan Majumdar

2012-11-11T23:59:59.000Z

358

Heavy hadrons in quark-gluon plasma  

SciTech Connect

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.

Narodetskii, I. M., E-mail: naro@itep.ru; Simonov, Yu. A.; Veselov, A. I. [Institute of Theoretical and Experimental Physics (Russian Federation)

2011-03-15T23:59:59.000Z

359

Was "beauty" a quark name they...  

NLE Websites -- All DOE Office Websites (Extended Search)

Was "beauty" a quark name they used in the past? There are several naming conventions in the High Energy Physics community. The names of the quarks don't necessarily mean anything...

360

String model for spinning quark jets  

Science Conference Proceedings (OSTI)

A string model of quark hadronization, taking the quark spin degree of freedom into account, is proposed. The method for using the model in a Monte-Carlo code for jet generation is given.

Artru, X.; Belghobsi, Z. [Universite de Lyon, CNRS/IN2P3 and Universite Lyon 1, Institut de Physique Nucleaire de Lyon, Laboratoire de Physique Theorique, Universite de Jijel (Algeria)

2012-06-27T23:59:59.000Z

Note: This page contains sample records for the topic "top quark mass" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Supercomputing Challenge top winners: Los Alamos schools  

NLE Websites -- All DOE Office Websites (Extended Search)

Supercomputing Challenge top winners: Los Alamos schools Supercomputing Challenge top winners: Los Alamos schools Cole Kendrick won the top prize for his research project,...

362

Exotic mesons from quantum chromodynamics with improved gluon and quark actions on the anisotropic lattice  

E-Print Network (OSTI)

Hybrid (exotic) mesons, which are important predictions of quantum chromodynamics (QCD), are states of quarks and anti-quarks bound by excited gluons. First principle lattice study of such states would help us understand the role of ``dynamical'' color in low energy QCD and provide valuable information for experimental search for these new particles. In this paper, we apply both improved gluon and quark actions to the hybrid mesons, which might be more efficient than the previous works in reducing lattice spacing error and finite volume effect. Quenched simulations were done at $\\beta=2.6$ and on a $\\xi=3$ anisotropic $12^3 \\times 36$ lattice using our PC cluster. We obtain $2013 \\pm 26 \\pm 71$ MeV for the mass of the $1^{-+}$ hybrid meson ${\\bar q}qg$ in the light quark sector, and $4369 \\pm 37 \\pm 99$Mev in the charm quark sector; the mass splitting between the $1^{-+}$ hybrid meson ${\\bar c}c g$ in the charm quark sector and the spin averaged S-wave charmonium mass is estimated to be $1302 \\pm 37 \\pm 99$ M...

Mei, Z H; Mei, Zhong-Hao; Luo, Xiang-Qian

2003-01-01T23:59:59.000Z

363

QuarkNet at Work  

NLE Websites -- All DOE Office Websites (Extended Search)

QuarkNet at Work Information for Active Mentors & Teachers     QuarkNet Home - Information - Calendar - Contacts - Projects - Forms: EoI - Teachers Information Active Centers Calendar Contacts Expectations: for Teachers, for Mentors Information on Other Funding Sources Program Overview Support: for Teachers, for Centers Staff Job Description Activities Essential Practices - Teaching with Inquiry (word.doc) Classroom Activities e-Labs: CMS - Cosmic Ray Boot Camp Project Activities Databases: Data Entry (password only) 2012 Center Reporting Resources Important Findings from Previous Years Mentor Tips Associate Teacher Institute Toolkit Print Bibliography - Online Resources Imaging Detector Principles of Professionalism for Science Educators - NSTA position

364

Top Science of 2013  

NLE Websites -- All DOE Office Websites (Extended Search)

Space probes predict hazards to protect spacecraft Space probes predict hazards to protect spacecraft /science-innovation/_assets/images/icon-science.jpg Top Science of 2013 Our strong interdisciplinary teaming and unique research facilities allow us to develop solutions to complex problems, and to support partners and collaborators, all with the goal of strengthening national security and making a safer world. Space probes predict hazards to protect spacecraft placeholder Researchers think they've solved a 50-year-old space mystery about how electrons within the Van Allen radiation belts that surround our planet can become energetic enough to cripple orbiting satellites. With data collected by space-probe instruments, they discovered how electromagnetic radio waves cause electrons in these belts to greatly

365

Top Science of 2013  

NLE Websites -- All DOE Office Websites (Extended Search)

RAPTOR telescope witnesses black hole birth RAPTOR telescope witnesses black hole birth /science-innovation/_assets/images/icon-science.jpg Top Science of 2013 Our strong interdisciplinary teaming and unique research facilities allow us to develop solutions to complex problems, and to support partners and collaborators, all with the goal of strengthening national security and making a safer world. RAPTOR telescope witnesses black hole birth placeholder The first "thinking telescope" RAPTOR found the birth of big black holes, possibly the most powerful events since the big bang. This robotic array screens 100 million objects and runs real-time analysis-autonomously alerting us when there's a discovery or a threat. In 2006, RAPTOR was the first of its kind to make a discovery: the birth of

366

Scaling quark gluon plasma by HBT interferometry with lepton pairs  

E-Print Network (OSTI)

We study the intensity interferometry with lepton pairs for nuclear collisions at RHIC and LHC energies. It is argued that the invariant mass dependence of HBT radii extracted from the correlation functions of dilepton pairs can be used as an efficient tool to scale the size and life time of the quark gluon plasma expected to be formed in nuclear collisions at RHIC and LHC. Quantitatively different magnitudes of HBT radii are obtained at RHIC and LHC indicating stronger radial flow at LHC.

Payal Mohanty; Jan-e Alam

2012-02-10T23:59:59.000Z

367

Lattice QCD thermodynamics with Wilson quarks  

E-Print Network (OSTI)

We review studies of QCD thermodynamics by lattice QCD simulations with dynamical Wilson quarks. After explaining the basic properties of QCD with Wilson quarks at finite temperature including the phase structure and the scaling properties around the chiral phase transition, we discuss the critical temperature, the equation of state and heavy-quark free energies.

Shinji Ejiri

2007-04-27T23:59:59.000Z

368

The Unquenching of the Quark Model  

Science Conference Proceedings (OSTI)

We present an unquenched quark model for baryons in which the effects of quark-antiquark pair creation (uu-bar, dd and ss-bar) are taken into account in an explicit form via a microscopic, QCD-inspired, quark-antiquark creation mechanism. As an application we discuss the flavor content of octet baryons.

Santopinto, Elena [INFN, via Dodecaneso 33, 16164 Genova (Italy); Bijker, Roelof [ICN-UNAM, AP 70-543, 04510 Mexico DF (Mexico)

2011-05-24T23:59:59.000Z

369

Color superconductivity and the strange quark  

E-Print Network (OSTI)

At ultra-high density, matter is expected to form a degenerate Fermi gas of quarks in which there is a condensate of Cooper pairs of quarks near the Fermi surface: color superconductivity. In these proceedings I review some of the underlying physics, and discuss outstanding questions about the phase structure of ultra-dense quark matter.

Mark G Alford

2005-12-01T23:59:59.000Z

370

LATTICE QCD THERMODYNAMICS WITH WILSON QUARKS.  

SciTech Connect

We review studies of QCD thermodynamics by lattice QCD simulations with dynamical Wilson quarks. After explaining the basic properties of QCD with Wilson quarks at finite temperature including the phase structure and the scaling properties around the chiral phase transition, we discuss the critical temperature, the equation of state and heavy-quark free energies.

EJIRI,S.

2007-11-20T23:59:59.000Z

371

Heavy Quark Production at the Tevatron  

E-Print Network (OSTI)

Results are presented from four CDF analyses involving heavy quark production in proton-antiproton collisions at center of mass energy 1.96 TeV. The shapes of b-jets are found to be broader than inclusive predictions and broader than both PYTHIA and HERWIG defaults. A measurement of the production cross section for psi(2S) is consistent with Run 1 results and with theoretical predictions associated with parton distribution function energy dependence. The inclusive b-jet production cross section is also consistent with theoretical predictions over six orders of magnitude. The b-bbar differential production cross section is compared to several theoretical models and found to be best described by MC@NLO + JIMMY.

Sally Seidel

2008-08-25T23:59:59.000Z

372

Two-Loop Leading Color Corrections to Heavy-Quark Pair Production in the Gluon Fusion Channel  

E-Print Network (OSTI)

We evaluate the two-loop QCD diagrams contributing to the leading color coefficient of the heavy-quark pair production cross section in the gluon fusion channel. We obtain an analytic expression, which is valid for any value of the Mandelstam invariants s and t and of the heavy-quark mass m. Our findings agree with previous analytic results in the small-mass limit and with recent results for the coefficients of the IR poles.

R. Bonciani; A. Ferroglia; T. Gehrmann; A. von Manteuffel; C. Studerus

2010-11-30T23:59:59.000Z

373

Search for heavy vector-like quarks coupling to light quarks in proton-proton collisions at root s=7 TeV with the ATLAS detector  

Science Conference Proceedings (OSTI)

This Letter presents a search for singly produced vector-like quarks, Q, coupling to light quarks, q. The search is sensitive to both charged current (CC) and neutral current (NC) processes, pp {yields} Qq {yields} Wqq{prime} and pp {yields} Qq {yields} Zqq{prime} with a leptonic decay of the vector gauge boson. In 1.04 fb{sup -1} of data taken in 2011 by the ATLAS experiment at a center-of-mass energy {radical}s = 7 TeV, no evidence of such heavy vector-like quarks is observed above the expected Standard Model background. Limits on the heavy vector-like quark production cross section times branching ratio as a function of mass m{sub Q} are obtained. For a coupling {kappa}{sub qQ} = v/m{sub Q}, where v is the Higgs vacuum expectation value, 95% C.L. lower limits on the mass of a vector-like quark are set at 900 GeV and 760 GeV from CC and NC processes, respectively.

Aad G.; Abbott, B.; Abdallah, J.; Khalek, S. Abdel; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; AbouZeid, O. S. s; Abramowicz, H.; Abreu, H.; Acerbi, E.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Addy, T. N.; Adelman, J.; et al.

2012-05-30T23:59:59.000Z

374

Lattice test of 1/N[subscript c] baryon mass relations  

E-Print Network (OSTI)

1/N[subscript c] baryon mass relations are compared with lattice simulations of baryon masses using different values of the light-quark masses, and hence different values of SU(3) flavor-symmetry breaking. The lattice ...

Jenkins, Elizabeth E.

375

Fermion Masses and Coupling Unification in E6. Life in the Desert  

E-Print Network (OSTI)

We present an $E_6$ Grand Unified model with a realistic pattern of fermion masses. All standard model fermions are unified in three fundamental 27-plets (i.e. supersymmetry is not invoked), which involve in addition right handed neutrinos and three families of vector like heavy quarks and leptons. The lightest of those can lie in the low TeV range, being accessible to future collider experiments. Due to the high symmetry, the masses and mixings of all fermions are closely related. The new heavy fermions play a crucial role for the quark and lepton mass matrices and the bilarge neutrino oscillations. In all channels generation mixing and ${\\cal CP}$ violation arise from a single antisymmetric matrix. The $E_6$ breaking proceeds via an intermediate energy region with $SU(3)_L\\tm SU(3)_R\\tm SU(3)_C$ gauge symmetry and a discrete left-right symmetry. This breaking pattern leads in a straightforward way to the unification of the three gauge coupling constants at high scales, providing for a long proton lifetime. The model also provides for the unification of the top, bottom and tau Yukawa couplings and for new interesting relations in flavor and generation space.

Berthold Stech; Zurab Tavartkiladze

2003-11-12T23:59:59.000Z

376

HIggs Boson Mass in the Minimal Unified Subquark Model  

E-Print Network (OSTI)

In the original paper entitled, "Masses of Fundamental Particles", not only the masses of fundamental particles including the weak bosons, Higgs scalar, quarks, and leptons, but also the mixing angles of quarks and those of neutrinos are all explained and/or predicted in the unified composite model of quarks and leptons successfully. In this addendum entitled, "Higgs Boson Mass in the Minimal Unified Subquark Model", it is emphasized that the Higgs boson mass is predicted to be about 130Gev in the minimal unified subquark model, which agrees well with the experimental values of 125-126GeV recently found by the ATLAS and CMS Collaborations at the LHC.

Hidezumi Terazawa

2011-09-17T23:59:59.000Z

377

Fermi National Accelerator Laboratory June 2012  

NLE Websites -- All DOE Office Websites (Extended Search)

two distinct top-quark production mechanisms Explored a new mass range for the Higgs boson and constrained its mass through top-quark and W-boson mass measurements Observed...

378

Electric polarizability of the neutron in dynamical quark ensembles  

E-Print Network (OSTI)

The background field method for measuring the electric polarizability of the neutron is adapted to the dynamical quark case, resulting in the calculation of (certain space-time integrals over) three- and four-point functions. Particular care is taken to disentangle polarizability effects from the effects of subjecting the neutron to a constant background gauge field; such a field is not a pure gauge on a finite lattice and engenders a mass shift of its own. At a pion mass of m_pi = 759 MeV, a small, slightly negative electric polarizability is found for the neutron.

Michael Engelhardt

2007-10-09T23:59:59.000Z

379

Self-consistent quasiparticle model for quark-gluon plasma  

E-Print Network (OSTI)

Here we present a self-consistent quasi-particle model for quark-gluon plasma and apply it to explain the non-ideal behaviour seen in lattice simulations. The basic idea, borrowed from electrodynamic plasma, is that the gluons acquire mass as it propagates through plasma due to collective effects and is approximately equal to the plasma frequency. The statistical mechanics and thermodynamics of such a system is studied by treating it as an ideal gas of massive gluons. Since mass or plasma frequency depends on density, which itself is a thermodynamic quantity, the whole problem need to be solved self-consistently.

Vishnu M. Bannur

2006-09-19T23:59:59.000Z

380

On the origin of families of quarks and leptons - predictions for four families  

E-Print Network (OSTI)

The approach unifying all the internal degrees of freedom--proposed by one of us--is offering a new way of understanding families of quarks and leptons: A part of the starting Lagrange density in d(=1+13), which includes two kinds of spin connection fields--the gauge fields of two types of Clifford algebra objects--transforms the right handed quarks and leptons into the left handed ones manifesting in d=1+3 the Yukawa couplings of the Standard model. We study the influence of the way of breaking symmetries on the Yukawa couplings and estimate properties of the fourth family--the quark masses and the mixing matrix, investigating the possibility that the fourth family of quarks and leptons appears at low enough energies to be observable with the new generation of accelerators.

G. Bregar; M. Breskvar; D. Lukman; N. S. Mankoc Borstnik

2007-08-21T23:59:59.000Z

Note: This page contains sample records for the topic "top quark mass" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Past, present and future highlights in top and higgs physics from the CDF experiment  

SciTech Connect

The 1992-1995 running of the Fermilab Tevatron (the so-called Run 1) ended with many important physics goals accomplished, including the discovery of the top quark, and the anticipation of many further questions be to answered in the future. In March 2002, after many detector upgrades by both the CDF and D0 experiments, and significant upgrades of the accelerator itself, the Tevatron Run 2 began (after a detector commissioning run) with the ultimate goal of discovering the Higgs boson. Here, we will highlight some important Run 1 results from CDF in the areas of top quark and Higgs boson physics, show some preliminary studies from Run 2, and give some expectations of what Run 2 will ultimately provide to our understanding of matter.

M. C. Kruse

2003-12-15T23:59:59.000Z

382

Origin of quark-lepton flavor in SO(10) with type II seesaw mechanism  

SciTech Connect

Diverse mass and mixing patterns between the quarks and leptons makes it challenging to construct a simple grand unified theory of flavor. We show that SO(10) supersymmetry grand unified theories with type II seesaw mechanism giving neutrino masses provide a natural framework for addressing this issue. A simple ansatz that the dominant Yukawa matrix (the 10-Higgs coupling to matter) has rank one appears to simultaneously explain both the large lepton mixings as well as the observed quark flavor hierarchy in these models. A testable prediction of this ansatz is the neutrino mixing, U{sub e3}, which should be observable in planned long baseline experiments.

Dutta, Bhaskar [Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States); Mimura, Yukihiro; Mohapatra, R. N. [Maryland Center for Fundamental Physics and Department of Physics, University of Maryland, College Park, Maryland, 20742 (United States)

2009-11-01T23:59:59.000Z

383

Search for quark-lepton compositeness in the dimuon final state at D0  

SciTech Connect

We used the upgraded D0 detector at the Tevatron at {radical}s = 1.96 TeV to collect data in a search for a compositeness signature of quarks and leptons. This analysis uses an integrated luminosity of 400 pb{sup -1}. The high-mass dimuon mass spectrum is compared with that predicted by Drell-Yan (DY) scattering, modified by a contact interaction. This interaction is parameterized by a compositeness energy scale factor {Lambda}. Preliminary limits on {lambda} are set at the 95% confidence level for constructive and destructive interference between the DY amplitude and the contact interaction for various quark and lepton chiralities.

Xuan, Nguyen Phuoc; /Notre Dame U.

2005-01-01T23:59:59.000Z

384

Classical strongly coupled quark-gluon plasma. VII. Energy loss  

Science Conference Proceedings (OSTI)

We use linear response analysis and the fluctuation-dissipation theorem to derive the energy loss of a heavy quark in the SU(2) classical Coulomb plasma in terms of the l=1 monopole and nonstatic structure factor. The result is valid for all Coulomb couplings {Gamma}=V/K, the ratio of the mean potential to kinetic energy. We use the Liouville equation in the collisionless limit to assess the SU(2) nonstatic structure factor. We find the energy loss to be strongly dependent on {Gamma}. In the liquid phase with {Gamma}{approx_equal}4, the energy loss is mostly metallic and soundless with neither a Cerenkov nor a Mach cone. Our analytical results compare favorably with the SU(2) molecular dynamics simulations at large momentum and for heavy quark masses.

Cho, Sungtae; Zahed, Ismail [Department of Physics and Astronomy, State University of New York, Stony Brook, New York 11794 (United States)

2010-12-15T23:59:59.000Z

385

Method for establishing a combustion zone in an in situ oil shale retort having a pocket at the top  

DOE Patents (OSTI)

An in situ oil shale retort having a top boundary of unfragmented formation and containing a fragmented permeable mass has a pocket at the top, that is, an open space between a portion of the top of the fragmented mass and the top boundary of unfragmented formation. To establish a combustion zone across the fragmented mass, a combustion zone is established in a portion of the fragmented mass which is proximate to the top boundary. A retort inlet mixture comprising oxygen is introduced to the fragmented mass to propagate the combustion zone across an upper portion of the fragmented mass. Simultaneously, cool fluid is introduced to the pocket to prevent overheating and thermal sloughing of formation from the top boundary into the pocket.

Cha, Chang Y. (1904 Glenmont Dr., Bakersfield, CA 93309)

1980-01-01T23:59:59.000Z

386

A New Mass Formula for NG Bosons in QCD  

E-Print Network (OSTI)

An often used mass formula for Nambu-Goldstone (NG) bosons in QCD, such as the pions, involves the condensate $$, $f_{\\pi}$ and the quark current masses. We argue, within the context of the Global Colour Model to QCD, that this expression is wrong. Analysis of the interplay between the Dyson-Schwinger equation for the constituent quark effect and the Bethe-Salpeter equation for the NG boson results in a new mass formula.

Reginald T. Cahill; Susan M. Gunner

1995-07-10T23:59:59.000Z

387

Subject Areas: Particle Physics A Viewpoint on: 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  

E-Print Network (OSTI)

Two collaborations at the Tevatron have combined data from their searches for the Higgs boson and report evidence of a new particle decaying into heavy quark pairs. This could be the first experimental evidence that the same mechanism that gives mass to the carriers of the weak force also underlies the mass of quarks.

Albert De Roeck

2012-01-01T23:59:59.000Z

388

Effective hadron theories from a quark model  

SciTech Connect

In the context of the quark exchange model of Lenz et al., effective hadron theories are constructed and the resulting physical observables compared to their ''experimental'' values as defined by the calculations using the exact quark model operators. This model study illustrates convergence issues for an effective hadron basis in a quark model in which all physical observables can be computed exactly.

Gardner, S.; Moniz, E.J.

1987-12-01T23:59:59.000Z

389

Dynamics of nano tippe top  

E-Print Network (OSTI)

We investigate the motion of a nano tippe top, which is formed from a C60 fullerene, and which is assumed to be spinning on either a graphene sheet or the interior of a single-walled carbon nanotube. We assume no specific geometric configuration for the top, however for example, the nano tippe top might be formed by joining a fullerene C60 with a small segment of a smaller radius carbon nanotube. We assume that it is spinning on a graphene sheet or a carbon nanotube surface only as a means of positioning and isolating the device, and the only effect of the graphene or the carbon nanotube surface is only through the frictional effect generated at the point of the contact. We employ the same basic physical ideas originating from the classical tippe top and find that the total retarding force, which comprises both a frictional force and a magnetic force at the contact point between the C60 fullerene and the graphene sheet or the inner surface of the single-walled carbon nanotube, induces the C60 molecule to spin and precess from a standing up position to a lying down position. Unlike the classical tippe top, the nanoscale tippe top does not flip over since the gravitational effect is not sufficient at the nano scale. After the precession, while the molecular top spins about its lying down axis, if we apply the opposite retarding magnetic force at the contact point, then the molecule will return to its standing up position. The standing up and the lying down configurations of the nano tippe top during the precession and retraction processes demonstrate its potential use as a memory device in nano-computing. 1

Yue Chan; Ngamta Thamwattana; James M. Hill

2009-01-01T23:59:59.000Z

390

Heavy quark thermodynamics in full QCD  

E-Print Network (OSTI)

We analyze the large-distance behaviour of static quark-anti-quark pair correlations in QCD. The singlet free energy is calculated and the entropy contribution to it is identified allowing us to calculate the excess internal energy. The free energy has a sharp drop in the critical region, leading to sharp peaks in both excess entropy and internal energy.

Konstantin Petrov; RBC-Bielefeld Collaboration

2007-01-22T23:59:59.000Z

391

Single Production of Fourth Family b' Quark at the Large Hadron electron Collider  

E-Print Network (OSTI)

We examined the single production of fourth family b' quarks at the Large Hadron electron Collider (LHeC).We have analyzed the background and the signal processes for the mass range 300-800 GeV. We find the discovery region for an optimal parametrization of the Vqb' matrix elements.

O. Cakir; V. Cetinkaya

2009-12-10T23:59:59.000Z

392

Evidence from Identified Particles for Active Quark and Gluon Degrees of Freedom  

E-Print Network (OSTI)

Measurements of intermediate pT (1.5 increase with event multiplicity much faster than meson production. The rate of increase is similar for all baryons, and seemingly independent of mass. This indicates that the number of constituent quarks determines the multiplicity dependence of identified hadron production at intermediate pT. We review these measurements and interpret the experimental findings.

Paul Sorensen

2007-01-23T23:59:59.000Z

393

Measurement of jet multiplicity in top pair events  

E-Print Network (OSTI)

The normalized differential $t\\bar t$ cross section in jet multiplicity bins is presented, measured in proton-proton collisions using 5.0~fb$^{-1}$ of data collected at $\\sqrt{s}$ = 7~\\TeV. The analysis is performed in the electron + jets and the muon + jets channels. The jet multiplicity distribution is sensitive to initial state radiation. A comparison of the data with different Monte Carlo generators is shown. After background subtraction, the data are in agreement with $t\\bar t$ signal Monte Carlo distributions. Additionally, the measurement of the top quark pair differential cross-section in the number of radiated additional hard partons in the muon + jets channel is presented. The measured fractions of events with $t\\bar t$ + 0, 1, and $\\geq$ 2 additional partons are in good agreement with different Monte Carlo predictions.

CMS Collaboration

2012-01-01T23:59:59.000Z

394

The Particle Adventure | What holds it together? | Quark confinement  

NLE Websites -- All DOE Office Websites (Extended Search)

Quark confinement Quark confinement Quark confinement Color-charged particles cannot be found individually. For this reason, the color-charged quarks are confined in groups (hadrons) with other quarks. These composites are color neutral. The development of the Standard Model's theory of the strong interactions reflected evidence that quarks combine only into baryons (three quark objects), and mesons (quark-antiquark objects), but not, for example, four-quark objects. Now we understand that only baryons (three different colors) and mesons (color and anticolor) are color-neutral. Particles such as ud or uddd that cannot be combined into color-neutral states are never observed. Color-Force Field The quarks in a given hadron madly exchange gluons. For this reason, physicists talk about the color-force field which consists of the gluons holding the bunch of quarks together.

395

The Particle Adventure | What holds it together? | Quarks emit gluons  

NLE Websites -- All DOE Office Websites (Extended Search)

holds it together? > Quarks emit gluons holds it together? > Quarks emit gluons Quarks emit gluons Color charge is always conserved. When a quark emits or absorbs a gluon, that quark's color must change in order to conserve color charge. For example, suppose a red quark changes into a blue quark and emits a red/antiblue gluon (the image below illustrates antiblue as yellow). The net color is still red. This is because - after the emission of the gluon - the blue color of the quark cancels with the antiblue color of the gluon. The remaining color then is the red color of the gluon. Quarks emit and absorb gluons very frequently within a hadron, so there is no way to observe the color of an individual quark. Within a hadron, though, the color of the two quarks exchanging a gluon will change in a way that keeps the bound system in a color-neutral state.

396

Color Diffusion and Conductivity in a Quark-Gluon Plasma  

E-Print Network (OSTI)

Color diffusion is shown to be an important dissipative property of quark-gluon plasmas that rapidly damps collective color modes. We derive the characteristic color relaxation time scale, $t_c\\approx (3\\alpha_s T \\log(m_E/m_M ))^{-1}$, showing its sensitivity to the ratio of the static color electric and magnetic screening masses. This leads to a surprisingly small color conductivity, $\\sigma_c\\approx 2 T/\\log(m_E/m_M)$, which in fact vanishes in the semi-classical (1-loop) limit.

Alexei V. Selikhov; Miklos Gyulassy

1993-07-07T23:59:59.000Z

397

Los Alamos National Laboratory top  

NLE Websites -- All DOE Office Websites (Extended Search)

top top science news of 2012 December 20, 2012 Scientific advances that caught the world's interest LOS ALAMOS, NEW MEXICO, December 20, 2012-In 2012 Los Alamos National Laboratory made its scientific mark in a wide variety of areas, and the stories that caught the public's attention and that of the science community reflect those broad capabilities. Top science stories for the year traveled from the canyons of Mars to the high desert forests of New Mexico, from cosmic particles to the structure of proteins and enzymes. Computer models of wildfires, and nuclear magnetic resonance signatures of plutonium, it all was fascinating for those following Los Alamos' science news. - 2 - Mars Science Laboratory Curiosity rover and ChemCam 2:12 ChemCam rock laser for the Mars Science Laboratory

398

MTS Table Top Load frame  

NLE Websites -- All DOE Office Websites (Extended Search)

MTS Table Top Load frame MTS Table Top Load frame The Non-destructive Evaluation group operates an MTS Table Top Load frame for ultimate strength and life cycle testing of various ceramic, ceramic-matrix (FGI), carbon, carbon fiber, cermet (CMC) and metal alloy engineering samples. The load frame is a servo-hydraulic type designed to function in a closed loop configuration under computer control. The system can perform non-cyclic, tension, compression and flexure testing and cyclic fatigue tests. The system is comprised of two parts: * The Load Frame and * The Control System. Load Frame The Load Frame (figure 1) is a cross-head assembly which includes a single moving grip, a stationary grip and LVDT position sensor. It can generate up to 25 kN (5.5 kip) of force in the sample under test and can

399

SRNL Microspheres Win Top Honors  

NLE Websites -- All DOE Office Websites (Extended Search)

Microspheres Microspheres Win Top Honors AIKEN, S.C. (July 16, 2012) - Savannah River National Laboratory (SRNL) captured top honors at a symposium spotlighting some of the most innovative research being conducted by the researchers supporting the U.S. Department of Energy's National Nuclear Security Administration (NNSA) . Dr. George Wicks of SRNL was presented the top "Award of Excellence" for the poster presen- tation on SRNL's porous-walled hollow glass microspheres at the NNSA Laboratory Directed Research and Development (LDRD) Symposium on Discovery and Innovation for National Security. The poster described how development of the microspheres began with funding from the Savannah River Site Plant-Directed Research and Development (PDRD) program, which funds

400

Top 10 Energy Efficiency Opportunities  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Top 10 Energy Efficiency Top 10 Energy Efficiency Opportunities Federal Utility Partnership Working Group San Francisco, 5/22/2013 Siva Sethuraman Customer Energy Solutions PG&E 2 Whole Building A comprehensive, performance-based approach to achieving 15+% energy savings in existing commercial buildings - quantification of energy use baselines and estimate savings at the whole building level leveraging the power of interval meter data. Behavioral Operational Retrofit Types of Energy Savings * Simplified, integrated offering * Bigger incentives tied to performance * Flexibility to pursue a range of measures overtime * Transparent and credible bill savings Baseline Analytics, Examples 3 Small Commercial EMS * Energy management system (EMS) products that offer integrated

Note: This page contains sample records for the topic "top quark mass" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Processing top k queries from samples  

Science Conference Proceedings (OSTI)

Top-k queries are desired aggregation operations on data sets. Examples of queries on network data include the top 100 source AS's, top 100 ports, or top Domain names over IP packets or over IP flow records. Since the complete dataset is often ...

Edith Cohen; Nadav Grossaug; Haim Kaplan

2006-12-01T23:59:59.000Z

402

Next-to-next-to-leading order soft gluon corrections in top quark hadroproduction.  

E-Print Network (OSTI)

by the Division of Nuclear Physics of the Office of High Energy and Nuclear Physics of the U.S. Department of Energy under Contract No. DE-AC-03-76SF00098. References [1] CDF Collaboration, F. Abe et al., Phys. Rev. Lett. 74, 2626 (1995); D0 Collaboration, S... of Cambridge, Madingley Road, Cambridge CB3 0HE, UK bNuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA and Physics Department, University of California at Davis, Davis, CA 95616, USA Abstract We calculate next...

Kidonakis, Nikolaos; Vogt, Ramona

403

Electric dipole moment of the top quark within an effective theory  

Science Conference Proceedings (OSTI)

Using the effective Lagrangian approach, we develope the trilinear contributions originated in the dimension-six electroweak invariants O-tilde{sub W} = (1/3){epsilon}{sub ijk}W{sup i{mu}}{sub v}W{sup jv}{sub {lambda}}W{sup k{lambda}}{sub {mu}} and O-tilde{sub WB} = (1/2)B-tilde{sub {alpha}}{sub {beta}}W{sup c{alpha}}{sup {beta}}{phi}{sup {dagger}}{tau}{sup c}{phi}, and then we insert the corresponding vertices in a one-loop ttV diagram, with V off-shell, generating the structure of the electric dipole moment. Using a nonlinear gauge, we prove that the results are gauge independent. Finally, we present the analytic expressions for the electric dipole form factors originated in each invariant introduced.

Novales-Sanchez, H. [Facutad de Ciencias Fisico-Matematicas, Benemerita Universidad Autonoma de Puebla. Apartado Postal 1152, Puebla, Pue. (Mexico); Toscano, J. J. [Instituto de Fisica y Matematicas, Universidad Michoacana de San Nicolas de Hidalgo, Edificio C-3, Ciudad Universitaria, C. P. 58040, Morelia, Michoacan (Mexico)

2009-04-20T23:59:59.000Z

404

FCNC top quark production via anomalous tqV couplings beyond leading order.  

E-Print Network (OSTI)

. Han, R.D. Peccei, and X. Zhang, Nucl. Phys. B454, 527 (1995); T. Han, K. Whisnant, B.L. Young, and X. Zhang, Phys. Lett. B 385, 311 (1996); E. Malkawi and T. Tait, Phys. Rev. D 54, 5758 (1996); T. Tait and C.P. Yuan, in reference [1]; M. Hosch, K... . Whisnant, and B.L. Young Phys. Rev. D 56, 5725 (1997); K.J. Abraham, K. Whisnant, and B.L. Young, Phys. Lett. B 419, 381 (1998); T. Han and J.L. Hewett, Phys. Rev. D 60, 074015 (1999); S. Bar-Shalom and J. Wudka, Phys. Rev. D 60, 094016 (1999); T. Han et al...

Kidonakis, Nikolaos; Belyaev, Alexander

405

Angular correlations of lepton pairs from vector boson and top quark decays in Monte Carlo simulations.  

E-Print Network (OSTI)

if the particle P has spin different from zero. The process of eq. (1.1) has production angular correlations if its matrix elements have a non-trivial dependence on (di ·a), (di·b), or (di·X). It is therefore clear that the decay chain approximation can account...

Frixione, Stefano; Laenen, Eric; Motylinski, Patrick; Webber, Bryan R

406

SUSY QCD Corrections to Higgs Pair Production from Bottom Quark Fusion  

E-Print Network (OSTI)

We present a complete next-to-leading order (NLO) calculation for the total cross section for inclusive Higgs pair production via bottom-quark fusion at the CERN Large Hadron Collider (LHC) in the minimal supersymmetric standard model (MSSM) and the minimal supergravity model (mSUGRA). We emphasize the contributions of squark and gluino loops (SQCD) and the decoupling properties of our results for heavy squark and gluino masses. The enhanced couplings of the b quark to the Higgs bosons in supersymmetric models with large tanb yield large NLO SQCD corrections in some regions of parameter space.

Sally Dawson; Chung Kao; Yili Wang

2007-10-23T23:59:59.000Z

407

Quasiparticle Model of Quark-Gluon Plasma at Imaginary Chemical Potential  

E-Print Network (OSTI)

A quasiparticle model of the quark-gluon plasma is compared with lattice QCD data for purely imaginary chemical potential. Net quark number density, susceptibility as well as the deconfinement border line in the phase diagram of strongly interacting matter are investigated. In addition, the impact of baryo-chemical potential dependent quasiparticle masses is discussed. This accomplishes a direct test of the model for non-zero baryon density. The found results are compared with lattice QCD data for real chemical potential by means of analytic continuation and with a different (independent) set of lattice QCD data at zero chemical potential.

M. Bluhm; B. Kampfer

2007-11-05T23:59:59.000Z

408

Quark-Hadron Duality for Hybrid Mesons at Large-Nc  

E-Print Network (OSTI)

We investigate implications of quark-hadron duality for hybrid mesons in the large-Nc limit. A simple formalism is developed which implements duality for QCD two-point functions of currents of quark bilinears, with any number of gluons. We argue that the large-Nc meson masses share a common parameter, which is related to the QCD string tension. This parameter is fixed from correlators of conserved vector and axial-vector currents, and using lattice QCD determinations of the string tension. Our results predict towers of hybrid mesons which, within expected 1/Nc corrections, naturally accommodate the 1^(-+) experimental hybrid candidates.

S. R. Beane

2001-08-02T23:59:59.000Z

409

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

SciTech Connect

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.

Fogaca, D. A.; Navarra, F. S.; Franzon, B. [Instituto de Fisica, Universidade de Sao Paulo Rua do Matao, Travessa R, 187, 05508-090 Sao Paulo, SP (Brazil); Horvath, J. E. [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao, 1226, 05508-090, Sao Paulo, SP (Brazil)

2013-03-25T23:59:59.000Z

410

Limits on cosmological variation of quark masses and strong interaction  

E-Print Network (OSTI)

We discuss limits on variation of $(m_q/\\Lambda_{QCD})$. The results are obtained by studying $n-\\alpha$-interaction during Big Bang, Oklo natural nuclear reactor data and limits on variation of the proton $g$-factor from quasar absorpion spectra.

V. F. Dmitriev; V. V. Flambaum

2002-09-19T23:59:59.000Z

411

Top  

E-Print Network (OSTI)

annual authorized trade in ‘small arms ’ 1 exceeds USD 7 billion a year (Small Arms Survey, 2011a, p. 9). 2 A lack of transparency on the part of many states and difficulties of disaggregating data on transfers that some states do report create numerous challenges for the study of this activity. Lists of the most active countries tend to be skewed towards those that are more transparent. Nonetheless, sufficient data and expertise exist to allow for broad assessments to be made about the trade in small arms. This Research Note assesses the countries that import the greatest value of small arms. As highlighted in the Survey’s Research Note 11 (Small Arms Survey, 2011b), state reporting of small arms transfers is opaque or incomplete. In their submissions to international reporting mechanisms, such as the UN Commodity Trade Statistics Database (better known as UN Comtrade), the UN Register of Conventional Arms, and national reports, states either fail to report transfers or are selective in those that they report. Furthermore, international reporting mechanisms often aggregate various commodities, such as different types of weapon, into single categories, which makes it difficult to discern trade data on any one type of weapon. Since 2001 at least 15 countries have imported more than USD 100 million worth of small arms in a single calendar year. Analysis of the 2001–08 3 period indicates that the United States is the country with the largest recorded yearly imports, having received more than USD 1

Small Arms Transfers; The Small; Arms Survey

2011-01-01T23:59:59.000Z

412

Active QuarkNet Centers  

NLE Websites -- All DOE Office Websites (Extended Search)

first active year) first active year)       QuarkNet Home - Information - Calendar - Contacts - Projects - Forms: EoI - Teachers Institution Contact e-mail Year Brown, Northeastern & Brandeis Universities Richard Dower - rick.dower@roxburylatin.org 1999 Fermilab & University of Chicago Chris Stoughton - stoughto@fnal.gov 1999 Florida State University Horst Wahl - wahl@hep.fsu.edu 1999 Indiana University Rick Van Kooten - rickv@paoli.physics.indiana.edu 1999 University of California - Santa Cruz Steve Ritz - ritz@scipp.ucsc.edu 1999 University of Notre Dame Dan Karmgard - Karmgard.1@nd.edu 1999 University of Oklahoma Michael Strauss - strauss@mail.nhn.ou.edu 1999 University of Rochester Kevin McFarland - ksmcf@pas.rochester.edu 1999

413

Threshold corrections in bottom and charm quark hadroproduction at next-to-next-to-leading order.  

E-Print Network (OSTI)

ar X iv :h ep -p h/ 04 01 05 6v 1 9 Ja n 20 04 Cavendish-HEP-04/01 LBNL-54251 Threshold corrections in bottom and charm quark hadroproduction at next-to-next-to-leading order Nikolaos Kidonakisa and Ramona Vogtb aCavendish Laboratory, University... be either qq or gg. A more detailed discussion of the kinematics can be found in Ref. [2]. In 1PI kinematics, a single heavy quark is identified so that i(pa) + j(pb) ?? Q(p1) +X[Q](p2) (2.1) where Q is the identified bottom or charm quark of mass m and X...

Kidonakis, Nikolaos; Vogt, Ramona

414

Two-point gauge invariant quark Green's functions with polygonal phase factor lines  

E-Print Network (OSTI)

Polygonal lines are used for the paths of the gluon field phase factors entering in the definition of gauge invariant quark Green's functions. This allows classification of the Green's functions according to the number of segments the polygonal lines contain. Functional relations are established between Green's functions with polygonal lines with different numbers of segments. An integrodifferential equation is obtained for the quark two-point Green's function with a path along a single straight line segment where the kernels are represented by a series of Wilson loop averages along polygonal contours. The equation is exactly and analytically solved in the case of two-dimensional QCD in the large-$N_c$ limit. The solution displays generation of an infinite number of dynamical quark masses accompanied with branch point singularities that are stronger than simple poles. An approximation scheme, based on the counting of functional derivatives of Wilson loops, is proposed for the resolution of the equation in four dimensions.

H. Sazdjian

2013-10-24T23:59:59.000Z

415

Matching heavy-light currents with NRQCD and HISQ quarks  

E-Print Network (OSTI)

We calculate the one loop renormalisation parameters for the heavy-light axial-vector and vector currents using lattice perturbation theory. We use NonRelativistic QCD (NRQCD) heavy quarks and the Highly Improved Staggered Quark (HISQ) action for the light quarks. We present results for heavy-light currents with massless HISQ quarks and briefly discuss the extension to heavy-heavy currents with massive HISQ quarks.

Christopher Monahan; Christine Davies; Ron Horgan; G. Peter Lepage; Heechang Na; Junko Shigemitsu

2012-10-25T23:59:59.000Z

416

History of exotic Meson (4-quark) and Baryon (5-quark) States  

E-Print Network (OSTI)

I briefly review the history of exotic meson (4-quark) and baryon (5-quark) states, which is rooted in the formalism of Regge pole and duality. There are robust model-independent predictions for the exchange of 4-quark (Baryonium) Regge trajectories in several processes, which are strongly supported by experiment. On the other hand the predictions for the spectroscopy of 4-quark resonances are based on specific QCD inspired models, with some experimental support. The corresponding predictions for the recently discovered exotic baryon (Pentaquark) state are briefly discussed.

D. P. Roy

2003-11-17T23:59:59.000Z

417

Heavy quark production from jet conversions in a quark-gluon plasma  

E-Print Network (OSTI)

Recently, it has been demonstrated that the chemical composition of jets in heavy ion collisions is significantly altered compared to the jets in the vacuum. This signal can be used to probe the medium formed in nuclear collisions. In this study we investigate the possibility that fast light quarks and gluons can convert to heavy quarks when passing through a quark-gluon plasma. We study the rate of light to heavy jet conversions in a consistent Fokker-Planck framework and investigate their impact on the production of high-p(T) charm and bottom quarks at the Relativistic Heavy Ion Collider and the Large Hadron Collider.

Liu, W.; Fries, Rainer J.

2008-01-01T23:59:59.000Z

418

Y scaling in a simple quark model  

SciTech Connect

A simple quark model is used to define a nuclear pair model, that is, two composite hadrons interacting only through quark interchange and bound in an overall potential. An equivalent hadron model is developed, displaying an effective hadron-hadron interaction which is strongly repulsive. We compare the effective hadron model results with the exact quark model observables in the kinematic region of large momentum transfer, small energy transfer. The nucleon response function in this y-scaling region is, within the traditional framework, sensitive to the nucleon momentum distribution at large momentum. We find a surprisingly small effect of hadron substructure. Furthermore, we find in our model that a simple parametrization of modified hadron size in the bound state, motivated by the bound quark momentum distribution, is not a useful way to correlate different observables.

Kumano, S.; Moniz, E.J.

1988-05-01T23:59:59.000Z

419

The crystallography of three flavor quark matter  

E-Print Network (OSTI)

The nature of cold three-flavor quark matter at the large (but not asymptotic) densities relevant to neutron star phenomenology is not resolved. The gapless CFL phase, which was previously believed to have the lowest free ...

Sharma, Rishi, Ph. D. Massachusetts Institute of Technology

2007-01-01T23:59:59.000Z

420

Quark matter conductivity in strong magnetic background  

SciTech Connect

Applying the ideas and methods of condensed matter physics we calculate the quantum conductivity of quark matter in magnetic field. In strong field quantum conductivity is proportional to the square root of the field.

Kerbikov, B. O., E-mail: borisk@itep.ru [Institute for Theoretical and Experimental Physics (Russian Federation)

2012-06-15T23:59:59.000Z

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