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Note: This page contains sample records for the topic "quark gluon plasma" from the National Library of EnergyBeta (NLEBeta).
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1

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

2

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

3

Hunting the Quark Gluon Plasma ASSESSMENTS  

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

Hunting the Quark Gluon Plasma Hunting the Quark Gluon Plasma ASSESSMENTS BY THE EXPERIMENTAL COLLABORATIONS Relativistic Heavy Ion Collider (RHIC) * Brookhaven National Laboratory, Upton, NY 11974-5000 RESULTS FROM THE FIRST 3 YEARS AT RHIC managed for the U.S. Department of Energy by Brookhaven Science Associates, a company founded by Stony Brook University and Battelle April 18, 2005 BNL -73847-2005 Formal Report

4

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

5

Quark-gluon plasma (Selected Topics)  

SciTech Connect

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

Zakharov, V. I., E-mail: vzakharov@itep.ru [Institute for Theoretical and Experimental Physics (Russian Federation)

2012-09-15T23:59:59.000Z

6

Quark-Gluon Plasma Thermalization and Plasma Instabilities  

E-Print Network (OSTI)

In this talk, I review the important role played by plasma instabilities in the thermalization of quark-gluon plasmas at very high energy. [Conference talk presented at Strong and Electroweak Mattter 2004, Helsinki, Finland, June 16--19.

Peter Arnold

2004-08-31T23:59:59.000Z

7

Fluctuations of Chromodynamic Fields in Quark-Gluon Plasma  

E-Print Network (OSTI)

Chromodynamic fluctuations in the collisionless quark-gluon plasma are found as a solution of the initial value linearized problem. The stable and unstable plasmas are discussed.

Mrowczynski, Stanislaw

2008-01-01T23:59:59.000Z

8

Photon production from an anisotropic quark-gluon plasma  

E-Print Network (OSTI)

We calculate photon production from a quark-gluon plasma which is anisotropic in momentum space including the Compton scattering and quark/anti-quark annihilation processes. We show that for a quark-gluon plasma which has an oblate momentum-space anisotropy the photon production rate has an angular dependence which is peaked transverse to the beam line. We propose to use the angular dependence of high-energy medium photon production to experimentally determine the degree of momentum-space isotropy of a quark-gluon plasma produced in relativistic heavy-ion collisions.

Bjoern Schenke; Michael Strickland

2006-11-27T23:59:59.000Z

9

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

10

Black holes and the quark-gluon plasma  

E-Print Network (OSTI)

I discuss the possibility that the quark-gluon plasma at strong coupling admits a description in terms of a black hole in asymptotically anti-de Sitter space.

George Siopsis

2009-01-26T23:59:59.000Z

11

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

12

On the Dynamics of Unstable Quark-Gluon Plasma  

E-Print Network (OSTI)

Since the quark-gluon plasma, which is unstable due to anisotropic momentum distribution, evolves fast in time, plasma's characteristics have to be studied as initial value problems. The chromodynamic fluctuations and the momentum broadening of a fast parton traversing the plasma are discussed here. The two quantities are shown to exponentially grow in time.

Stanislaw Mrowczynski

2009-10-30T23:59:59.000Z

13

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

14

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

15

J/psi Production in Quark-Gluon Plasma  

E-Print Network (OSTI)

We study J/psi production at RHIC and LHC energies with both initial production and regeneration. We solve the coupled set of transport equation for the J/psi distribution in phase space and the hydrodynamic equation for evolution of quark-gluon plasma. At RHIC, continuous regeneration is crucial for the J/psi momentum distribution while the elliptic flow is still dominated by initial production. At LHC energy, almost all the initially created J\\psis are dissociated in the medium and regeneration dominates the J/psi properties.

Li Yan; Pengfei Zhuang; Nu Xu

2006-08-03T23:59:59.000Z

16

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

17

Quark-gluon plasma in an external magnetic field  

E-Print Network (OSTI)

Using numerical simulations of lattice QCD we calculate the effect of an external magnetic field on the equation of state of the quark-gluon plasma. The results are obtained using a Taylor expansion of the pressure with respect to the magnetic field for the first time. The coefficients of the expansion are computed to second order in the magnetic field. Our setup for the external magnetic field avoids complications arising from toroidal boundary conditions, making a Taylor series expansion straightforward. This study is exploratory and is meant to serve as a proof of principle.

L. Levkova; C. DeTar

2013-09-04T23:59:59.000Z

18

The Fluid Nature of Quark-Gluon Plasma  

E-Print Network (OSTI)

Collisions of heavy nuclei at very high energies offer the exciting possibility of experimentally exploring the phase transformation from hadronic to partonic degrees of freedom which is predicted to occur at several times normal nuclear density and/or for temperatures in excess of $\\sim 170$ MeV. Such a state, often referred to as a quark-gluon plasma, is thought to have been the dominant form of matter in the universe in the first few microseconds after the Big Bang. Data from the first five years of heavy ion collisions of Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) clearly demonstrate that these very high temperatures and densities have been achieved. While there are strong suggestions of the role of quark degrees of freedom in determining the final-state distributions of the produced matter, there is also compelling evidence that the matter does {\\em not} behave as a quasi-ideal state of free quarks and gluons. Rather, its behavior is that of a dense fluid with very low kinematic viscosity exhibiting strong hydrodynamic flow and nearly complete absorption of high momentum probes. The current status of the RHIC experimental studies is presented, with a special emphasis on the fluid properties of the created matter, which may in fact be the most perfect fluid ever studied in the laboratory.

W. A. Zajc

2008-02-25T23:59:59.000Z

19

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

20

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

Science Conference Proceedings (OSTI)

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

Begun, V. V., E-mail: viktor.begun@gmail.com; Gorenstein, M. I., E-mail: goren@bitp.kiev.ua; Mogilevsky, O. A. [Bogolyubov Institute for Theoretical Physics (Ukraine)

2012-07-15T23:59:59.000Z

Note: This page contains sample records for the topic "quark gluon plasma" 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

Non-linear waves in a Quark Gluon Plasma  

E-Print Network (OSTI)

Recent measurements at RHIC suggest that a nearly perfect fluid of quarks and gluons is produced in AA collisions. Moreover the passage of supersonic partons through this medium seems to produce waves. These waves might pile up and form Mach cones, which would manifest themselves in the so called away-side jets, forming a broad structure in the angular distribution of the particles recoiling against a trigger jet of moderate energy. In most of the theoretical descriptions of these phenomena, the hydrodynamic equations are linearized for simplicity. We propose an alternative explanation for the observed broadening of the away-side peak. It is based on hydrodynamics but it is a consequence of the non-linearities of the equations, which instead of simple waves may lead to localized waves or even solitons. We investigate in detail the consequences of including the non-linear terms. We use a simple equation of state for the QGP and expand the hydrodynamic equations around equilibrium configurations. The resulting differential equations describe the propagation of perturbations in the energy density. We solve them numerically and find that localized perturbations can propagate for long distances in the plasma. Under certain conditions our solutions mimick the propagation of Korteweg - de Vries solitons.

D. A. Fogaça; L. G. Ferreira Filho; F. S. Navarra

2009-08-28T23:59:59.000Z

22

Jet-Tagged Back-Scattering Photons For Quark Gluon Plasma Tomography  

E-Print Network (OSTI)

Direct photons are important probes for quark gluon plasma created in high energy nuclear collisions. Various sources of direct photons in nuclear collisions are known, each of them endowed with characteristic information about the production process. However, it has been challenging to separate direct photon sources through measurements of single inclusive photon spectra and photon azimuthal asymmetry. Here we explore a method to identify photons created from the back-scattering of high momentum quarks off quark gluon plasma. We show that the correlation of back-scattering photons with a trigger jet leads to a signal that should be measurable at RHIC and LHC.

Rainer J. Fries; Somnath De; Dinesh K. Srivastava

2012-11-05T23:59:59.000Z

23

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

E-Print Network (OSTI)

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

Riek, F.; Rapp, Ralf.

2010-01-01T23:59:59.000Z

24

Geek-Up[11.05.10]: Quark Gluon Plasma, Solar-Power Generating Windows and  

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

05.10]: Quark Gluon Plasma, Solar-Power Generating 05.10]: Quark Gluon Plasma, Solar-Power Generating Windows and CCS Field Studies Geek-Up[11.05.10]: Quark Gluon Plasma, Solar-Power Generating Windows and CCS Field Studies November 5, 2010 - 4:08pm Addthis A simulated collision of lead-ions, courtesy the ALICE experiment at CERN A simulated collision of lead-ions, courtesy the ALICE experiment at CERN Elizabeth Meckes Elizabeth Meckes Director of User Experience & Digital Technologies, Office of Public Affairs More than 1,700 scientists, engineers, technicians and students from seven Department of Energy national laboratories, 89 American universities and one supercomputer center celebrated progress this week when the Large Hadron Collider's (LHC) first record-setting run of high-energy proton collisions ended.

25

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...

26

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

27

Comment on the paper "Energy Loss of Charm Quarks in the Quark-Gluon Plasma : Collisional vs Radiative"  

E-Print Network (OSTI)

In the article by M. G. Mustafa published in Phys. Rev. C {\\bf 72}, 014905 (2005) the author has estimated the total energy loss of a charm quark and quenching of hadron spectra due to the collisional energy loss of energetic partons in an expanding quark-gluon plasma employing Fokker-Planck equation. We wish to point out through this comment that some of conceptual and numerical results of the said paper are unreliable.

Mishra, M; Patra, B K

2007-01-01T23:59:59.000Z

28

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

29

Dileptons, spectral weights, and conductivity in the Quark-Gluon Plasma  

E-Print Network (OSTI)

We re-examine soft dilepton emission from a weakly coupled Quark-Gluon Plasma. We show that Braaten, Pisarski, and Yuan's result that the dilepton rate rises as E^-4 (and the spectral weight scales as 1/E) at small energy Econductivity. We evaluate the spectral weight in the E~g^4 T region by kinetic theory techniques and show that it satisfies a sum rule, which makes the determination of electrical conductivity from the Euclidean correlation function very challenging.

Guy D. Moore; Jean-Marie Robert

2006-07-14T23:59:59.000Z

30

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

31

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

SciTech Connect

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

Grassi, Frederique [Instituto de Fisica, Universidade de Sao Paulo (Brazil)

2013-03-25T23:59:59.000Z

32

Negative Off-Diagonal Conductivities in a Weakly Coupled Quark Gluon Plasma  

E-Print Network (OSTI)

We calculate the conductivity matrix of a weakly coupled quark-gluon plasma at the leading-log order. By setting all quark chemical potentials to be identical, the diagonal conductivities become degenerate and positive, while the off-diagonal ones become degenerate but negative (or zero when the chemical potential vanishes). This means a potential gradient of a certain fermion flavor can drive backward currents of other flavors. A simple explanation is provided for this seemingly counter intuitive phenomenon. It is speculated that this phenomenon is generic and most easily measured in cold atom experiments.

Jiunn-Wei Chen; Yen-Fu Liu; Shi Pu; Yu-Kun Song; Qun Wang

2013-08-13T23:59:59.000Z

33

Negative Off-Diagonal Conductivities in a Weakly Coupled Quark Gluon Plasma  

E-Print Network (OSTI)

We calculate the conductivity matrix of a weakly coupled quark-gluon plasma at the leading-log order. By setting all quark chemical potentials to be identical, the diagonal conductivities become degenerate and positive, while the off-diagonal ones become degenerate but negative (or zero when the chemical potential vanishes). This means a potential gradient of a certain fermion flavor can drive backward currents of other flavors. A simple explanation is provided for this seemingly counter intuitive phenomenon. It is speculated that this phenomenon is generic and most easily measured in cold atom experiments.

Chen, Jiunn-Wei; Pu, Shi; Song, Yu-Kun; Wang, Qun

2013-01-01T23:59:59.000Z

34

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

35

Transport properties of the quark-gluon plasma from lattice QCD  

E-Print Network (OSTI)

I review the progress made in extracting transport properties of the quark-gluon plasma from lattice QCD simulations. The information on shear and bulk viscosity, the "low-energy constants" of hydrodynamics, is encoded in the retarded correlators of Tmunu, the energy-momentum tensor. Euclidean correlators, computable on the lattice, are related to the retarded correlators by an integral transform. The most promising strategy to extract shear and bulk viscosity is to study the shear and sound channel correlators where the hydrodynamic modes dominate. I present preliminary results from a comprehensive study of the gluonic plasma between 0.95Tc and 4.0Tc.

Harvey B. Meyer

2009-07-23T23:59:59.000Z

36

Estimation of electric conductivity of the quark gluon plasma via asymmetric heavy-ion collisions  

E-Print Network (OSTI)

We show that in asymmetric heavy-ion collisions, especially off-central Cu+Au collisions, a sizable strength of electric field directed from Au nucleus to Cu nucleus is generated in the overlapping region, because of the difference in the number of electric charges between the two nuclei. This electric field would induce an electric current in the matter created after the collision, which result in a dipole deformation of the charge distribution. The directed flow parameters $v_1^{\\pm}$ of charged particles turn out to be sensitive to the charge dipole and provide us with information about electric conductivity of the quark gluon plasma.

Yuji Hirono; Masaru Hongo; Tetsufumi Hirano

2012-11-06T23:59:59.000Z

37

Energy Loss of Gluons, Baryons and k-Quarks in an N=4 SYM Plasma  

E-Print Network (OSTI)

We consider different types of external color sources that move through a strongly-coupled thermal N=4 super-Yang-Mills plasma, and calculate, via the AdS/CFT correspondence, the dissipative force (or equivalently, the rate of energy loss) they experience. A bound state of k quarks in the totally antisymmetric representation is found to feel a force with a nontrivial k-dependence. Our result for k=1 (or k=N-1) agrees at large N with the one obtained recently by Herzog et al. and Gubser, but contains in addition an infinite series of 1/N corrections. The baryon (k=N) is seen to experience no drag. Finally, a heavy gluon is found to be subject to a force which at large N is twice as large as the one experienced by a heavy quark, in accordance with gauge theory expectations.

Mariano Chernicoff; Alberto Guijosa

2006-11-15T23:59:59.000Z

38

Equilibration of anisotropic quark-gluon plasma produced by decays of color flux tubes  

E-Print Network (OSTI)

A set of kinetic equations is used to study equilibration of the anisotropic quark-gluon plasma produced by decays of color flux tubes possibly created at the very early stages of ultra-relativistic heavy-ion collisions. The decay rates of the initial color fields are given by the Schwinger formula, and the collision terms are treated in the relaxation-time approximation. By connecting the relaxation time with viscosity we are able to study production and thermalization processes in the plasma characterized by different values of the ratio of the shear viscosity to entropy density, eta/s. For the lowest (KSS) value of this ratio, 4 pi eta/s = 1, and realistic initial conditions for the fields, the system approaches the viscous-hydrodynamics regime within 1-2 fm/c. On the other hand, for larger values of the viscosity, 4 pi eta/s greater or equal to 3, the collisions in the plasma become inefficient to destroy collective phenomena which manifest themselves as oscillations of different plasma parameters. The presence of such oscillations brings in differences between the kinetic and hydrodynamic descriptions, which suggest that the viscous-hydrodynamics approach after 1-2 fm/c is not complete if 4 pi eta/s is greater or equal to 3 and should be extended to include dissipative phenomena connected with color conductivity.

Radoslaw Ryblewski; Wojciech Florkowski

2013-07-01T23:59:59.000Z

39

SYSTEMATIC STUDIES OF HEAVY ION COLLISIONS TO SEARCH FOR QUARK-GLUON PLASMA  

SciTech Connect

This is the final technical report for DOE Outstanding Junior Investigator (OJI) Award, 'Systematic Studies of Heavy Ion Collisions to Search for Quark-Gluon Plasma', grant DE-FG02-02ER41219, Principal Investigator (PI) Fuqiang Wang. The research under the grant was divided into two phases. The first concentrated on systematic studies of soft hadron production at low transverse momentum (p{sub T}), in particular the production of (anti-)baryon and strangeness in heavy ion collisions at RHIC energies. The second concentrated on measurements of di-hadron and multi-hadron jet-correlations and investigations of medium response to jets. The research was conducted at the Relativistic Heavy-Ion Collider (RHIC) at BNL with the Solenoidal Tracker At RHIC (STAR) experiment. The total grant is $214,000. The grant established a PC farm solely used for this research. The PC farm consists of 8 nodes with a total of 16 CPUs and 3 disk servers of total 2 TB shared storage. The current balance of the grant is $19,985. The positive balance is because an initial purchase of $22,600 for the PC farm came out of the PI's start-up fund due to the lateness of the award. The PC farm is an integral part of the Purdue Physics Department's computer cluster. The grant supported two Ph.D. graduate students. Levente Molnar was supported from July 2002 to December 2003, and worked on soft hadron production. His thesis title is Systematics of Identified Particle Production in pp, d-Au and Au-Au Collisions at RHIC Energies. He graduated in 2006 and now is a Postdoctoral fellow at INFN Sezione di Bari, Italy working on the ALICE experiment at the LHC. Jason Ulery was supported from January 2004 to July 2007. His thesis title is Two- and Three-Particle Jet-Like Correlations. He defended his thesis in October 2007 and is moving to Frankfurt University, Germany to work on the ALICE experiment at the LHC. The research by this grant resulted in 7 journal publications (2 PRL, 1 PLB, 1 PRC, 2 submitted and 1 in preparation), and 14 invited talks and 10 contributed talks at major conferences. These are listed at end of this report.

Fuqiang Wang

2007-11-29T23:59:59.000Z

40

Heavy-quark probes of the quark-gluon plasma and interpretation of recent data taken at the BNL Relativistic Heavy Ion Collider  

E-Print Network (OSTI)

Thermalization and collective flow of charm (c) and bottom (b) quarks in ultrarelativistic heavy-ion collisions are evaluated based on elastic parton rescattering in an expanding quark-gluon plasma (QGP). We show that resonant interactions in a strongly interacting QGP (sQGP), as well as parton coalescence, can play an essential role in the interpretation of recent data from the BNL Relativistic Heavy-Ion Collider (RHIC), and thus illuminate the nature of the sQGP and its hadronization. Our main assumption, motivated by recent findings in lattice quantum chromodynamics, is the existence of D- and B-meson states in the sQGP, providing resonant cross sections for heavy quarks. Pertinent drag and diffusion coefficients are implemented into a relativistic Langevin simulation to compute transverse-momentum spectra and azimuthal asymmetries (v(2)) of b- and c-quarks in Au-Au collisions at RHIC. After hadronization into D- and B-mesons using quark coalescence and fragmentation, associated electron-decay spectra and v(2) are compared to recent RHIC data. Our results suggest a reevaluation of radiative and elastic quark energy-loss mechanisms in the sQGP.

van Hees, H.; Greco, V.; Rapp, Ralf.

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "quark gluon plasma" 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

Suppression of bottomonia states in finite size quark gluon plasma in PbPb collisions at Large Hadron Collider  

E-Print Network (OSTI)

The bottomonium states due to their varying binding energies dissolve at different temperatures and thus their nuclear modification factors and relative yields have potential to map the properties of Quark Gluon Plasma (QGP). We estimate the suppression of bottomonia states due to color screening in an expanding QGP of finite lifetime and size with the conditions relevant for PbPb collisions at LHC. The properties of $\\Upsilon$ states and recent results on their dissociation temperatures have been used as ingredient in the study. The nuclear modification factors and the ratios of yields of $\\Upsilon$ states are then obtained as a function of transverse momentum and centrality. We compare our theoretical calculations with the bottomonia yields measured with CMS in PbPb collisions at $\\sqrt{s_{\\rm NN}}$ = 2.76 TeV. The model calculations explain the data very well.

A. Abdulsalam; Prashant Shukla

2012-10-29T23:59:59.000Z

42

Viewing the Chemical Evolution of the Quark-Gluon Plasma with Charge Balance Functions  

E-Print Network (OSTI)

Correlations from charge conservation are affected by when charge/anticharge pairs are created during the course of a relativistic heavy ion collision. For charges created early, balancing charges are typically separated by the order of one unit of spatial rapidity by the end of the collision, whereas those charges produced later in the collision are far more correlated. By analyzing correlations from STAR for different species, I show that one can distinguish the two separate waves of charge creation expected in a high-energy collision, one at early times when the QGP is formed and a second at hadronization. Further, I extract the density of up, down and strange quarks at in the QGP and find agreement at the 20% level with expectations for a chemically thermalized plasma.

Scott Pratt

2013-04-09T23:59:59.000Z

43

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.

44

Electrical conductivity of the quark-gluon plasma and soft photon spectrum in heavy-ion collisions  

E-Print Network (OSTI)

We extract the electrical conductivity $\\sigma_0$ of the quark gluon plasma(QGP) and study the effects of magnetic field and chiral anomaly on soft photon azimuthal anisotropy, $v_2$, based on the thermal photon spectrum at $0.4~GeVenergy. As a basis for our analysis, we derive the behavior of retarded photon self energy of a strongly interacting neutral plasma in hydrodynamic regime in the presence of magnetic field and chiral anomaly. By evolving the resulting soft thermal photon production rate over the realistic hydrodynamic background and comparing the results with the preliminary data from the PHENIX Collaboration, we found that the electrical conductivity at QGP temperature is in the range: $0.5<\\sigma_0/(e^{2}T) <1.1$, which is comparable with recent studies on lattice. We also compare the contribution from the magnetic field and chiral anomaly to soft thermal photon $v_{2}$ with the data. We argue that at LHC, the chiral magnetic wave would give negative contribution to photon $v_2$.

Yi Yin

2013-12-16T23:59:59.000Z

45

Quark and Gluon Condensates in Isospin Matter  

E-Print Network (OSTI)

Applying the Hellmann-Feynman theorem to a charged pion gas, the quark and gluon condensates at low isospin density are determined by precise pion properties. At intermediate density around $ f_\\pi^2m_\\pi$, from both the estimation for the dilute pion gas and the calculation with Nambu--Jona-Lasinio model, the quark condensate is strongly and monotonously suppressed, while the gluon condensate is enhanced and can be larger than its vacuum value. This unusual behavior of the gluon condensate is universal for Bose condensed matter of mesons. Our results can be tested by lattice calculations at finite isospin density.

Lianyi He; Yin Jiang; Pengfei Zhuang

2008-12-01T23:59:59.000Z

46

Gluon propagators and center vortices in gluon plasma  

E-Print Network (OSTI)

We study electric and magnetic components of the gluon propagators in quark-gluon plasma in terms of center vortices by using a quenched simulation of SU(2) lattice theory. In the Landau gauge, the magnetic components of the propagators are strongly affected in the infrared region by removal of the center vortices, while the electric components are almost unchanged by this procedure. In the Coulomb gauge, the time-time correlators, including an instantaneous interaction, also have an essential contribution from the center vortices. As a result, one finds that magnetic degrees of freedom in the infrared region couple strongly to the center vortices in the deconfinement phase.

M. N. Chernodub; Y. Nakagawa; A. Nakamura; T. Saito; V. I. Zakharov

2011-05-25T23:59:59.000Z

47

Electrical conductivity of the quark-gluon plasma across the deconfinement transition  

E-Print Network (OSTI)

A lattice calculation is presented for the electrical conductivity of the QCD plasma with 2+1 dynamical flavours at nonzero temperature. We employ the conserved lattice current on anisotropic lattices using a tadpole-improved clover action and study the behaviour of the conductivity over a wide range of temperatures, both below and above the deconfining transition. The conductivity is extracted from a spectral-function analysis using the Maximal Entropy Method, and a discussion of its systematics is provided.

Alessandro Amato; Gert Aarts; Chris Allton; Pietro Giudice; Simon Hands; Jon-Ivar Skullerud

2013-07-25T23:59:59.000Z

48

Electrical conductivity of the quark-gluon plasma across the deconfinement transition  

E-Print Network (OSTI)

A lattice calculation is presented for the electrical conductivity of the QCD plasma with 2+1 dynamical flavours at nonzero temperature. We employ the conserved lattice current on anisotropic lattices using a tadpole-improved clover action and study the behaviour of the conductivity over a wide range of temperatures, both below and above the deconfining transition. The conductivity is extracted from a spectral-function analysis using the Maximal Entropy Method, and a discussion of its systematics is provided.

Amato, Alessandro; Allton, Chris; Giudice, Pietro; Hands, Simon; Skullerud, Jon-Ivar

2013-01-01T23:59:59.000Z

49

Nonperturbative results on the quark-gluon vertex  

E-Print Network (OSTI)

We present analytical and numerical results for the Dirac form factor of the quark-gluon vertex in the quark symmetric limit, where the incoming and outgoing quark momenta have the same magnitude but opposite sign. To accomplish this, we compute the relevant components of the quark-ghost scattering kernel at the one-loop dressed approximation, using as basic ingredients the full quark propagator, obtained as a solution of the quark gap equation, and the gluon propagator and ghost dressing function, obtained from large-volume lattice simulations.

A. C. Aguilar; D. Binosi; J. C. Cardona; J. Papavassiliou

2013-01-17T23:59:59.000Z

50

How does gluon string split into two quark ones  

Science Conference Proceedings (OSTI)

In this paper, the authors assume that gluon string splits into two quark ones and not instantaneously but via creation of the so-called zip-antizip pairs along the gluon string. This additional stage prolongs hadronization process and gives the novel source of fluctuations that softens hadron z-spectrum and widens the multiplicity distribution.

Gurvich, E.G.; Leptoukh, G.G. (Inst. of Physics of the Georgian Academy of Sciences, Tamarashvili 6, Tbilisi (USSR))

1992-09-28T23:59:59.000Z

51

Heavy quarks, gluons and the confinement potential in Coulomb gauge  

SciTech Connect

We consider the heavy quark limit of Coulomb gauge QCD, with the truncation of the Yang-Mills sector to include only (dressed) two-point functions. We find that the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is nonperturbatively exact and moreover, we provide a direct connection between the temporal gluon propagator and the quark confinement potential. Further, we show that only bound states of color singlet quark-antiquark (meson) and quark-quark (SU(2) baryon) pairs are physically allowed.

Popovici, Carina; Watson, Peter; Reinhardt, Hugo [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2011-05-23T23:59:59.000Z

52

Transport Coefficients of Gluon Plasma  

E-Print Network (OSTI)

Transport coefficients of gluon plasma are calculated for a SU(3) pure gauge model by lattice QCD simulations on $16^3 \\times 8$ and $24^3 \\times 8$ lattices. Simulations are carried out at a slightly above the deconfinement transition temperature $T_c$, where a new state of matter is currently being pursued in RHIC experiments. Our results show that the ratio of the shear viscosity to the entropy is less than one and the bulk viscosity is consistent with zero in the region, $1.4 \\leq T/T_c \\leq 1.8 $.

Atsushi Nakamura; Sunao Sakai

2004-06-08T23:59:59.000Z

53

Early thermalization of quark-gluon matter initially created in high-energy nucleus-nucleus collisions  

E-Print Network (OSTI)

Elastic parton-parton-parton scattering is briefly reviewed and is included in transport equations of quark-gluon matter. We solve the transport equations and get thermal states from initially produced quark-gluon matter. Both gluon matter and quark matter take early thermalization, but gloun matter has a shorter thermalization time than quark matter.

Xu, Xiao-Ming

2013-01-01T23:59:59.000Z

54

Probing gluon nuclear PDF with direct photon production in association with a heavy quark  

E-Print Network (OSTI)

We investigate a possible use of direct photon production in association with a heavy quark in $pA$ collisions at the large hadron collider to constrain the nuclear gluon parton distribution function. This process is sensitive to both, the nuclear heavy quark and gluon parton distribution functions and is a very promising candidate to help determine the gluon nuclear PDF which is still largely untested.

K. Kovarik; T. Stavreva

2011-07-15T23:59:59.000Z

55

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

56

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

57

Hard Probes and Soft Ones for Testing the Quark-Gluon Soup By Paul Preuss  

E-Print Network (OSTI)

Hard Probes and Soft Ones for Testing the Quark-Gluon Soup By Paul Preuss "We call short-wavelength probes 'hard'; the shorter the wavelength, the smaller the features it can resolve. For example, you can Science Division, explaining the title of the recent Second International Conference on Hard

Knowles, David William

58

Probing Quark-Gluon Structure of Matter with e-p and e-A Reactions  

Science Conference Proceedings (OSTI)

Understanding the strong interaction (QCD) in the truly strong ('non-perturbative') region remains a major challenge in modern physics. Nucleon and nuclei provide natural laboratories to study the strong interaction. The quark-gluon structure of the nucleon and nuclei are important by themselves since they are the main (>99%) part of the visible world. With electroweak interaction well-understood, e-p and e-A are clean means to probe the nucleon and nuclear structure and to study the strong interaction (QCD). Inclusive Deep-Inelastic Scattering (DIS) experiments have provided us with the most extensive information on the unpolarized and longitudinally-polarized parton (quark and gluon) distributions (PDFs). It has becoming clear that transverse spin and transverse structure (both transverse spatial structure via generalized parton distributions (GPDs) and transverse momentum structure via transverse- momentum-dependent distributions (TMDs)) study are crucial for a more complete understanding of the nucleon structure and the dynamics of the strong interaction(QCD). The transverse spin, GPDs and TMDs have been the subjects of increasingly intense theoretical and experimental study recently. With 12 GeV energy upgrade, Jefferson Lab (JLab) will provide the most precise multi-dimensional map of the TMDs and GPDs in the valence quark region through Semi-Inclusive DIS (SIDIS) and Deep-Exclusive experiments, providing a 3-d partonic picture of the nucleon in momentum and spatial spaces. The precision information on TMDs and GPDs will provide access to the quark orbital angular momentum and its correlation with the quark and the nucleon spins. The planned future Electron-Ion Collider (EIC) will enable a precision study of the TMDs and GPDs of the sea quarks and gluons, in addition to completing the study in the valence region. The EIC will also open a new window to study the role of gluons in nuclei.

Jian-Ping Chen

2011-11-01T23:59:59.000Z

59

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

60

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

Note: This page contains sample records for the topic "quark gluon plasma" 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.


61

The second order hydrodynamic transport coefficient $?$ for the gluon plasma from the lattice  

E-Print Network (OSTI)

The quark gluon plasma produced in heavy ion collisions behaves like an almost ideal fluid described by viscous hydrodynamics with a number of transport coefficients. The second order coefficient $\\kappa$ is related to a Euclidean correlator of the energy-momentum tensor at vanishing frequency and low momentum. This allows for a lattice determination without maximum entropy methods or modelling, but the required lattice sizes represent a formidable challenge. We calculate $\\kappa$ in leading order lattice perturbation theory and simulations on $120^3\\times 6,8$ lattices with $afuture.

Owe Philipsen; Christian Schäfer

2013-11-26T23:59:59.000Z

62

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

63

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

SciTech Connect

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

Boer, Daniel; /Groningen U.; Diehl, Markus; /DESY; Milner, Richard; /MIT; Venugopalan, Raju; /Brookhaven; Vogelsang, Werner; /Tubingen U.; Kaplan, David; /Washington U., Seattle; Montgomery, Hugh; /Jefferson Lab; Vigdor, Steven; /Brookhaven; Accardi, A.; /Jefferson Lab; Aschenauer, E.C.; /Brookhaven; Burkardt, M.; /New Mexico State U.; Ent, R.; /Jefferson Lab; Guzey, V.; /Jefferson Lab; Hasch, D.; /Frascati; Kumar, K.; /Massachusetts U., Amherst; Lamont, M.A.C.; /Brookhaven; Li, Ying-chuan; /Brookhaven; Marciano, W.; /Brookhaven; Marquet, C.; /CERN; Sabatie, F.; /IRFU, SPhN, Saclay; Stratmann, M.; /Brookhaven /LBL, Berkeley /Buenos Aires U. /Antwerp U. /Pelotas U. /Moncton U. /Santa Maria U., Valparaiso /CCTVal, Valparaiso /Hefei, CUST /Shandong U., Weihai /Boskovic Inst., Zagreb /Zagreb U., Phys. Dept. /Jyvaskyla U. /Orsay, LPT /Paris U., VI-VII /Ecole Polytechnique, CPHT /IRFU, SPhN, Saclay /Saclay, SPhT /Ruhr U., Bochum /Giessen U. /DESY /Hamburg U., Inst. Theor. Phys. II /Heidelberg U. /Mainz U., Inst. Kernphys. /Mainz U., Inst. Phys. /Regensburg U. /Tubingen U. /Wuppertal U. /DESY /Cagliari U. /INFN, Cagliari /Frascati /Milan U. /INFN, Milan /INFN, Pavia /Pavia U. /INFN, Perugia /Perugia U.; /more authors..

2012-06-07T23:59:59.000Z

64

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

65

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

66

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

67

Properties of the SU(Nc) Gluon Plasma  

E-Print Network (OSTI)

We investigate the deconfinement transition in SU(Nc) gauge theories, and properties of the deconfined phase. A detailed lattice study of SU(4) and SU(6) gauge theories are conducted, and finite volume and cutoff effects on thermodynamic observables are studied. The scaling of the deconfinement transition point with lattice spacing is used to calculate the scale, Lambda_MSbar. The continuum estimates of the thermodynamic quantities are used to study properties of the gluon plasma. In particular, the approach to conformal limit is studied. We do not find any evidence of a strongly coupled, conformal phase in these theories.

Saumen Datta; Sourendu Gupta

2009-10-15T23:59:59.000Z

68

Probing the Quark Sea and Gluons: the Electron-Ion Collider Projects  

Science Conference Proceedings (OSTI)

EIC is the generic name for the nuclear science-driven Electron-Ion Collider presently considered in the US. Such an EIC would be the world’s first polarized electron-proton collider, and the world’s first e-A collider. Very little remains known about the dynamical basis of the structure of hadrons and nuclei in terms of the fundamental quarks and gluons of Quantum Chromodynamics (QCD). A large community effort to sharpen a compelling nuclear science case for an EIC occurred during a ten-week program taking place at the Institute for Nuclear Theory (INT) in Seattle from September 13 to November 19, 2010. The critical capabilities of a stage-I EIC are a range in center-of-mass energies from 20 to 70 GeV and variable, full polarization of electrons and light ions (the latter both longitudinal and transverse), ion species up to A=200 or so, multiple interaction regions, and a high luminosity of about 10{sup 34} electron-nucleons per cm{sup 2} and per second. The physics program of such a stage-I EIC encompass inclusive measurements (ep/A{yields}e'+X), which require detection of the scattered lepon and/or the full scattered hadronic debris with high precision, semi-inclusive processes (ep/A{yields}e'+h+X), which require detection in coincidence with the scattered lepton of at least one (current or target region) hadron; and exclusive processes (ep/A{yields}e'+N'/A'+{gamma}/m), which require detection of all particles in the reaction. The main science themes of an EIC are to i) map the spin and spatial structure of quarks and gluons in nucleons, ii) discover the collective effects of gluons in atomic nuclei, and (iii) understand the emergence of hadronic matter from color charge. In addition, there are opportunities at an EIC for fundamental symmetry and nucleon structure measurements using the electroweak probe. To truly make headway to image the sea quarks and gluons in nucleons and nuclei, the EIC needs high luminosity over a range of energies as more exclusive scattering probabilities are small, and any integrated detector/interaction region design needs to provide uniform coverage to detect spectator and diffractive products. This is because e-p and even more e-A colliders have a large fraction of their science related to what happens to the nucleon or ion beams. As a result, the philosophy of integration of complex detectors into an extended interaction region faces challenging constraints. Designs feature crossing angles between the protons or heavy ions during collisions with electrons, to remove potential problems for the detector induced by synchrotron radiation. Designs allocate quite some detector space before the final-focus ion quads, at the cost of luminosity, given that uniform detection coverage is a must for deep exclusive and diffractive processes. The integrated EIC detector/interaction region design at JLab focused on establishing full acceptance for such processes over a wide range of proton energies (20-100 GeV) with well achievable interaction region magnets. The detector design at BNL uses the higher ion beam energies to achieve good detection efficiency for instance for protons following a DVCS reaction, for proton beam energies starting from 100 GeV. Following a recommendation of the 2007 US Nuclear Science Long-Range Planning effort, the DOE Office of Nuclear Physics (DOE/NP) has allocated accelerator R&D funds to lay the foundation for a polarized EIC. BNL, in association with JLab and DOE/NP, has also established a generic detector R&D program to address the scientific requirements for measurements at a future EIC.

Rolf Ent

2012-04-01T23:59:59.000Z

69

200 A GeV Au+Au Collisions Serve a Nearly Perfect Quark-Gluon Liquid  

Science Conference Proceedings (OSTI)

A new robust method to extract the specific shear viscosity ({eta}/s){sub QGP} of a quark-gluon plasma (QGP) at temperatures T{sub c}

Song Huichao [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States); Bass, Steffen A. [Department of Physics, Duke University, Durham, North Carolina 27708 (United States); Heinz, Ulrich; Shen, Chun [Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States); Hirano, Tetsufumi [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2011-05-13T23:59:59.000Z

70

Gluons and the quark sea at high energies: distributions, polarization, tomography  

Science Conference Proceedings (OSTI)

This report is based on a ten-week program on Gluons and the quark sea at high-energies, which took place at the Institute for Nuclear Theory (INT) in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics (QCD). This report is organized around the following four major themes: (i) the spin and flavor structure of the proton, (ii) three dimensional structure of nucleons and nuclei in momentum and configuration space, (iii) QCD matter in nuclei, and (iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific opportunities presented by an EIC.

Boer, D.; Venugopalan, R.; Diehl, M.; Milner, R.; Vogelsang, W.; et al.

2011-09-30T23:59:59.000Z

71

Workshop on nuclear chromodynamics: Quarks and gluons in particles and nuclei  

SciTech Connect

The assertion that quantum chromodynamics (QCD) is the correct theory describing strong interaction phenomena has, largely by repetition, become rather non-controversial. It is likely even true. However, whether or not it is correct in detail, the experimentally supported realization that colored quarks and gluons are the elementary degrees of freedom, that asymptotic freedom makes short distance phenomena rather ''simple'' to understand, and that color is confined on the hadronic length scale of -- 1 fm has led to a profound change in the character of our attempts to understand the structure and interactions of both hadrons and nuclei. Many of the most important issued in particle physics and in nuclear physics are now seen to be intimately connected. An understanding of the validity and limits of effective theories based upon hadron degrees of freedom, so phenomenologically successful in describing a host of low energy phenomena, is coming into focus. The existence of new forms of matter grounded in the hidden color degree of freedom is predicted. These considerations form the subject of nuclear chromodynamics (NCD). The subject is far from mature and is developing rapidly.

Brodsky, S.; Moniz, E.

1985-01-01T23:59:59.000Z

72

Entropy production for an interacting quark-gluon plasma  

E-Print Network (OSTI)

We investigate the entropy production within dissipative hydrodynamics in the Israel-Stewart (IS) and Navier-Stokes theory (NS) for relativistic heavy ion physics applications. In particular we focus on the initial condition in a 0+1D Bjorken scenario, appropriate for the early longitudinal expansion stage of the collision. Going beyond the standard simplification of a massless ideal gas we consider a realistic equation of state consistently derived within a virial expansion. The EoS used is well in line with recent three-flavor QCD lattice data for the pressure, speed of sound, and interaction measure at nonzero temperature and vanishing chemical potential ($\\mu_{\\rm q} = 0$). The shear viscosity has been consistently calculated within this formalism using a kinetic approach in the ultra-relativistic regime with an explicit and systematic evaluation of the transport cross section as function of temperature. We investigate the influence of the viscosity and the initial condition, i.e. formation time, initial temperature, and pressure anisotropy for the entropy production at RHIC at $\\sqrt{s_{\\rm NN}}=130$ GeV. We find that the interplay between effects of the viscosity and of the realistic EoS can not be neglected in the reconstruction of the initial state from experimental data. Therefore, from the experimental findings it is very hard to derive unambiguous information about the initial conditions and/or the evolution of the system.

Stefano Mattiello

2011-05-17T23:59:59.000Z

73

Entropy production for an interacting quark-gluon plasma  

E-Print Network (OSTI)

We investigate the entropy production within dissipative hydrodynamics in the Israel-Stewart (IS) and Navier-Stokes theory (NS) for relativistic heavy ion physics applications. In particular we focus on the initial condition in a 0+1D Bjorken scenario, appropriate for the early longitudinal expansion stage of the collision. Going beyond the standard simplification of a massless ideal gas we consider a realistic equation of state consistently derived within a virial expansion. The EoS used is well in line with recent three-flavor QCD lattice data for the pressure, speed of sound, and interaction measure at nonzero temperature and vanishing chemical potential ($\\mu_{\\rm q} = 0$). The shear viscosity has been consistently calculated within this formalism using a kinetic approach in the ultra-relativistic regime with an explicit and systematic evaluation of the transport cross section as function of temperature. We investigate the influence of the viscosity and the initial condition, i.e. formation time, initial ...

Mattiello, Stefano

2011-01-01T23:59:59.000Z

74

Charmonium properties in the quark-gluon plasma  

E-Print Network (OSTI)

We present results for charmonium correlators and spectral functions in 2-flavour CD on anisotropic lattices. Our results indicate that the S-waves (J/psi and eta_c) survive up to temperatures close to 2T_c, while the P-waves (chi_c0 and chi_c1) melt away below 1.2T_c.

M. B. Oktay; M. J. Peardon; J. I. Skullerud; G. Aarts; C. R. Allton

2007-10-15T23:59:59.000Z

75

The Strongly Interacting Quark Gluon Plasma at RHIC and LHC  

E-Print Network (OSTI)

The study of heavy-ion collisions has currently unprecedented opportunities with two first class facilities, the Relativistic Heavy Ion Collider (RHIC) at BNL and the Large Hadron Collider (LHC) at CERN, and five large experiments ALICE, ATLAS, CMS, PHENIX and STAR producing a wealth of high quality data. Selected results recently obtained are presented on the study of flow, energy loss and direct photons.

Itzhak Tserruya

2012-12-30T23:59:59.000Z

76

Heavy Ion Physics and Quark-Gluon Plasma  

E-Print Network (OSTI)

These proceedings represent a brief overview of the exciting physics coming out from the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The experimental results from BRAHMS, PHOBOS, PHENIX and STAR indicate a strongly-coupled state of matter that can only be described on the partonic level. Here we review some of the latest experimental results as presented at the meeting of the Division of Particles and Fields of the American Physical Society in Riverside, CA in August 2004.

J. L. Nagle

2004-11-15T23:59:59.000Z

77

Quark-gluon plasma phenomenology from the lattice  

E-Print Network (OSTI)

The FASTSUM Collaboration has calculated several quantities relevant for QCD studies at non-zero temperature using the lattice technique. We report here our results for the (i) interquark potential in charmonium; (ii) bottomonium spectral functions; and (iii) electrical conductivity. All results were obtained with 2+1 flavours of dynamical fermions on an anisotropic lattice which allows greater resolution in the temporal direction.

Chris Allton; Gert Aarts; Alessandro Amato; Wynne Evans; Pietro Giudice; Simon Hands; Aoife Kelly; Seyong Kim; Maria-Paola Lombardo; Sinead Ryan; Jon-Ivar Skullerud; Tim Harris

2013-10-18T23:59:59.000Z

78

Glossary Term - Gluon  

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

Volt (eV) Previous Term (Electron Volt (eV)) Glossary Main Index Next Term (Half-life) Half-life Gluon Gluons are the particles responsible for binding quarks to each other....

79

Strangeness production in hadronic and quark matter: A quantitative differentiation  

SciTech Connect

We consider the production of strange particles in relativistic nucleus-nucleus collisions employing the hadron gas (HG) and quark-gluon plasma (QGP) formalism. We locate the region in the phase diagram where [mu][sub [ital s

Asprouli, M.N.; Panagiotou, A.D. (Physics Department, Nuclear Particle Physics Division, University of Athens, Panepistimiopolis, GR-157 71 Athens (Greece))

1995-02-01T23:59:59.000Z

80

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

Note: This page contains sample records for the topic "quark gluon plasma" 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.


81

Transport Coefficient of Gluon Plasma from Lattice QCD  

E-Print Network (OSTI)

In this report we present our calculation of the transport coefficient of gluon system on $24^3\\times 8$ lattice in the quench approximation. Simulations are carried out in the range, $1.4 \\le T/T_c \\le 24$. In the temperature region slightly above the transition, where the perturbative calculation is not applicable, the shear viscosity($\\eta$) is smaller than typical hadron masses. The bulk viscosity is consistent with zero within the range of error bars in $1.4 \\le T/T_c \\le 24$. We compare our results with the perturbative calculations in large $T/T_c$ region. It is found that the lattice and perturbative results are consistent with each other there. The ratio $\\eta/s$ is around $0.1-0.4$ in $T/T_c < 3$ region and satisfies the KSS bound\\cite{KSS}. In order to estimate the contribution from high frequency part of the spectral function, we study the effects of a term $\\rho^{high}$ proposed by Aarts and Resco\\cite{Aarts}. It is found that until the threshold mass becomes small, its effect is quite small, and that viscosity decreases as the threshold decreases. From these studies we think that although our result is obtained under an assumptions for the spectral function, it gives a reasonable estimation for $\\eta$($=\\pi d\\rho/d\\omega$ at $\\omega=0$), and qualitative results will not be changed when the accurate spectral function is obtained.

Sunao Sakai; Atsushi Nakamura

2005-10-24T23:59:59.000Z

82

Constituent Quarks and Gluons, Polyakov loop and the Hadron Resonance Gas Model  

E-Print Network (OSTI)

Based on first principle QCD arguments, it has been argued in arXiv:1204.2424[hep-ph] that the vacuum expectation value of the Polyakov loop can be represented in the hadron resonance gas model. We study this within the Polyakov-constituent quark model by implementing the quantum and local nature of the Polyakov loop hep-ph/0412308, hep-ph/0607338. The existence of exotic states in the spectrum is discussed.

Megias, E; Salcedo, L L

2013-01-01T23:59:59.000Z

83

Constituent Quarks and Gluons, Polyakov loop and the Hadron Resonance Gas Model  

E-Print Network (OSTI)

Based on first principle QCD arguments, it has been argued in arXiv:1204.2424[hep-ph] that the vacuum expectation value of the Polyakov loop can be represented in the hadron resonance gas model. We study this within the Polyakov-constituent quark model by implementing the quantum and local nature of the Polyakov loop hep-ph/0412308, hep-ph/0607338. The existence of exotic states in the spectrum is discussed.

E. Megias; E. Ruiz Arriola; L. L. Salcedo

2013-07-29T23:59:59.000Z

84

Next-to-leading order static gluon self-energy for anisotropic plasmas  

SciTech Connect

In this paper the structure of the next-to-leading order static gluon self-energy for an anisotropic plasma is investigated in the limit of a small momentum space anisotropy. Using the Ward identities for the static hard-loop (HL) gluon polarization tensor and the (nontrivial) static HL vertices, we derive a comparatively compact form for the complete next-to-leading order correction to the structure function containing the spacelike pole associated with magnetic instabilities. On the basis of a calculation without HL vertices, it has been conjectured that the imaginary part of this structure function is nonzero, rendering the spacelike poles integrable. We show that there are both positive and negative contributions when HL vertices are included, highlighting the necessity of a complete numerical evaluation, for which the present work provides the basis.

Carrington, M. E.; Rebhan, A. [Brandon University, Brandon, Manitoba, R7A 6A9 (Canada); Winnipeg Institute for Theoretical Physics, Winnipeg, Manitoba (Canada); Institut fuer Theoretische Physik, Technische Universitaet Wien, Wiedner Hauptstrasse 8-10, A-1040 Vienna (Austria)

2009-01-15T23:59:59.000Z

85

Experimental studies of the quark-gluon structure of nucleons and nuclei and of pion- and proton-nucleus interactions. Progress report, April 1, 1994--March 31, 1997  

SciTech Connect

This report summarizes the work on experimental research in intermediate energy nuclear physics carried out by New Mexico State University from April 1, 1994, through March 31, 1996 under a grant from the US Department of Energy. During this period we began phasing out our programs of study of pion-nucleus and pion-nucleon interaction and of nucleon-nucleus charge-exchange reactions, which have been our major focus of the past two or three years. At the same time we continued moving in a new direction of research on studies of the internal structure of nucleons and nuclei in terms of quarks and gluons. The pion and nucleon work has been aimed at improving our understanding of the nature of pion and proton interactions in the nuclear medium and of various aspects of nuclear structure. The studies of the quark-gluon structure of nucleons are aimed at clarifying such problems as the nature of the quark sea and the relation of the nucleon spin to the spins of the quarks within the nucleon, questions which are of a very fundamental nature.

NONE

1996-10-01T23:59:59.000Z

86

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...

87

Proton structure and tensor gluons  

E-Print Network (OSTI)

We consider a possibility that inside the proton and, more generally, inside the hadrons there are additional partons - tensor-gluons, which can carry a part of the proton momentum. The tensor-gluons have zero electric charge, like gluons, but have a larger spin. Inside the proton a nonzero density of the tensor-gluons can be generated by the emission of tensor-gluons by gluons. The last mechanism is typical for non-Abelian tensor gauge theories, in which there exists a gluon-tensor-tensor vertex of order g. Therefore the number of gluons changes not only because a quark may radiate a gluon or because a gluon may split into a quark-antiquark pair or into two gluons, but also because a gluon can split into two tensor-gluons. The process of gluon splitting suggests that part of the proton momentum which was carried by neutral partons is shared between vector and tensor gluons. We derive evolution equations for the parton distribution functions which take into account these new processes. The momentum sum rule allows to find the tensor-gluons contribution to the Callan-Simanzik beta function and to calculate the corresponding anomalous dimensions. This contribution changes the behavior of the structure functions, and the logarithmic correction to the Bjorken scaling becomes more mild. This also influences the unification scale at which the coupling constants of the Standard Model merge, shifting its value to lower energies of order of 40 TeV.

George Savvidy

2013-10-02T23:59:59.000Z

88

The lattice QCD simulation of the quark-gluon mixed condensate g at finite temperature and the phase transition of QCD  

E-Print Network (OSTI)

The thermal effects on the quark-gluon mixed condensate g, which is another chiral order parameter, are studied using the SU(3)c lattice QCD with the Kogut-Susskind fermion at the quenched level. We perform the accurate measurement of the mixed condensate as well as the quark condensate for 0MeVcondensates around T_c \\simeq 280MeV, while the thermal effects below T_c are found to be weak. We also find that the ratio m_0^2 = g/ is almost independent of the temperature even in the very vicinity of T_c, which indicates that the two condensates have nontrivial similarity in the chiral behaviors. We also present the correlation between the condensates and the Polyakov loop to understand the vacuum structure of QCD.

Takumi Doi; Noriyoshi Ishii; Makoto Oka; Hideo Suganuma

2004-09-14T23:59:59.000Z

89

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...

90

Energy loss and thermalization of heavy quarks in a strongly-coupled plasma  

E-Print Network (OSTI)

Using the AdS/CFT correspondence, we compute the medium-induced energy loss of a decelerating heavy quark moving through a strongly-coupled supersymmetric Yang Mills plasma. In the regime where the deceleration is small, a perturbative calculation is possible and we obtain the first two corrections to the energy-loss rate of a heavy quark with constant velocity. The thermalization of the heavy quark is also discussed.

Marquet, C; Xiao, B -W

2009-01-01T23:59:59.000Z

91

Imaginary part of the next-to-leading-order static gluon self-energy in an anisotropic plasma  

Science Conference Proceedings (OSTI)

Using hard-loop (HL) effective theory for an anisotropic non-Abelian plasma, which even in the static limit involves nonvanishing HL vertices, we calculate the imaginary part of the static next-to-leading-order gluon self-energy in the limit of a small anisotropy and with external momentum parallel to the anisotropy direction. At leading order, the static propagator has spacelike poles corresponding to plasma instabilities. On the basis of a calculation using bare vertices, it has been conjectured that, at next-to-leading order, the static gluon self-energy acquires an imaginary part which regulates these spacelike poles. We find that the one-loop resummed expression taken over naively from the imaginary-time formalism does yield a nonvanishing imaginary part even after including all HL vertices. However, this result is not correct. Starting from the real-time formalism, which is required in a nonequilibrium situation, we construct a resummed retarded HL propagator with correct causality properties and show that the static limit of the retarded one-loop-resummed gluon self-energy is real. This result is also required for the time-ordered propagator to exist at next-to-leading order.

Carrington, M. E.; Rebhan, A. [Brandon University, Brandon, Manitoba, R7A 6A9 (Canada) and Winnipeg Institute for Theoretical Physics, Winnipeg, Manitoba, R3T 2N2 (Canada); Institut fuer Theoretische Physik, Technische Universitaet Wien, Wiedner Hauptstrasse 8-10, A-1040 Vienna (Austria)

2009-09-15T23:59:59.000Z

92

Gluon field distribution in baryons  

E-Print Network (OSTI)

Methods for revealing the distribution of gluon fields within the three-quark static-baryon potential are presented. In particular, we outline methods for studying the sensitivity of the source on the emerging vacuum response for the three-quark system. At the same time, we explore the possibility of revealing gluon-field distributions in three-quark systems in QCD without the use of gauge-dependent smoothing techniques. Renderings of flux tubes from a preliminary high-statistics study on a 12^3 X 24 lattice are presented.

F. Bissey; F-G. Cao; A. Kitson; B. G. Lasscock; D. B. Leinweber; A. I. Signal; A. G. Williams; J. M. Zanotti

2005-01-05T23:59:59.000Z

93

Thermal processes generated in quark-gluon plasma by yoctosecond laser pulses  

E-Print Network (OSTI)

In this paper the thermal processes generated by yoctosecond (10-24 s) laser pulses in QGP are investigated. Considering that the relaxation time in QGP is of the order of 1 ys it is shown that in QGP the yoctosecond laser pulses can generate the thermal waves with velocity v = c (0.3 fm/ys). Key words: QGP, thermal waves, yoctosecond pulses

Marciak-Kozlowska, J

2011-01-01T23:59:59.000Z

94

Thermal processes generated in quark-gluon plasma by yoctosecond laser pulses  

E-Print Network (OSTI)

In this paper the thermal processes generated by yoctosecond (10-24 s) laser pulses in QGP are investigated. Considering that the relaxation time in QGP is of the order of 1 ys it is shown that in QGP the yoctosecond laser pulses can generate the thermal waves with velocity v = c (0.3 fm/ys). Key words: QGP, thermal waves, yoctosecond pulses

J. Marciak-Kozlowska; M. Kozlowski

2011-07-03T23:59:59.000Z

95

Geek-Up[11.05.10]: Quark Gluon Plasma, Solar-Power Generating...  

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

A simulation of the two-photon channel shows what ATLAS sees when the decay of a Higgs boson results in the production of two gamma rays. The blue beads indicate intermediate...

96

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

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

The toxic element arsenic sustains growth of a bacteria instead of phosphorus and CERN's Collider gives researchers a look into the matter that may have existed in the very first moments of the universe.

97

Strangeness at high temperatures: from hadrons to quarks  

E-Print Network (OSTI)

Appropriate combinations of up to fourth order cumulants of net strangeness fluctuations and their correlations with net baryon number and electric charge fluctuations, obtained from lattice QCD calculations, have been used to probe the strangeness carrying degrees of freedom at high temperatures. For temperatures up to the chiral crossover separate contributions of strange mesons and baryons can be well described by an uncorrelated gas of hadrons. Such a description breaks down in the chiral crossover region, suggesting that the deconfinement of strangeness takes place at the chiral crossover. On the other hand, the strangeness carrying degrees of freedom inside the quark gluon plasma can be described by a weakly interacting gas of quarks only for temperatures larger than twice the chiral crossover temperature. In the intermediate temperature window these observables show considerably richer structures, indicative of the strongly interacting nature of the quark gluon plasma.

A. Bazavov; H. -T. Ding; P. Hegde; O. Kaczmarek; F. Karsch; E. Laermann; Y. Maezawa; Swagato Mukherjee; H. Ohno; P. Petreczky; C. Schmidt; S. Sharma; W. Soeldner; M. Wagner

2013-04-26T23:59:59.000Z

98

Shock waves from heavy-quark mesons in AdS/CFT  

E-Print Network (OSTI)

We calculate the far-field stress-energy tensor of a quark gluon plasma due to a heavy-quark meson moving through it, using a semi-classical description in string theory of the meson as a string hanging into anti-de Sitter space. We find that these mesons create a shock wave but no diffusion wake, in contrast to single heavy quarks described via a trailing string, where the diffusion wake is strong. If thermal QCD responds similarly to heavy quarks and heavy quarkonia, the presence or suppression of the diffusion wake constitutes a prediction which can in principle be checked in heavy-ion collisions.

Steven S. Gubser; Silviu S. Pufu; Amos Yarom

2007-11-09T23:59:59.000Z

99

Holographic quark-antiquark potential in hot, anisotropic Yang-Mills plasma  

E-Print Network (OSTI)

Using the gauge/gravity duality we calculate the heavy quark-antiquark potential in a hot, anisotropic and strongly coupled Yang-Mills plasma in (3+1)-dimensions. As the anisotropic medium we take a deformed version of \\mathcal{N} = 4 super Yang-Mills theory at finite temperature following a recent work where the dual type IIB supergravity solution is also proposed. We turn on a small value of the anisotropy parameter, for which the gravity dual is known analytically (perturbatively), and compute the velocity-dependent quark-antiquark interaction potential when the pair is moving through the plasma with a velocity v. By setting v = 0 we recover the static quark-antiquark potential. We numerically study how the potential is modified in the presence of anisotropy. We further show numerically how the quark-antiquark separation (both in the static and the velocity-dependent case) and hence, the screening length gets modified by anisotropy. We discuss various cases depending upon the direction of the dipole and the direction of its propagation and make a comparative study of these cases. We are also able to obtain an analytical expression for the screening length of the dipole moving in a hot, anisotropic plasma in a special case.

Somdeb Chakraborty; Najmul Haque

2012-12-12T23:59:59.000Z

100

Cooking Up Hot Quark Soup | U.S. DOE Office of Science (SC)  

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

Cooking Up Hot Quark Soup Cooking Up Hot Quark Soup Stories of Discovery & Innovation Cooking Up Hot Quark Soup Enlarge Photo Image courtesy of Brookhaven National Laboratory These images contrast the degree of interaction and collective motion, or "flow," among quarks in the predicted gaseous quark-gluon plasma state (Figure on left, see mpeg animation ) vs. the liquid state that has been observed in gold-gold collisions at RHIC (Figure on right, see mpeg animation ). The green "force lines" and collective motion (visible on the animated version only) show the much higher degree of interaction and flow among the quarks in what is now being described as a nearly "perfect" liquid. Enlarge Photo Photo courtesy of Brookhaven National Laboratory Brookhaven National Laboratory's Relativistic

Note: This page contains sample records for the topic "quark gluon plasma" 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.


101

Nonabelian plasma instabilities in Bjorken expansion  

E-Print Network (OSTI)

Plasma instabilities are parametrically the dominant nonequilibrium dynamics of a weakly coupled quark-gluon plasma. In recent years the time evolution of the corresponding collective colour fields has been studied in stationary anisotropic situations. Here I report on recent numerical results on the time evolution of the most unstable modes in a longitudinally expanding plasma as they grow from small rapidity fluctuations to amplitudes where non-Abelian self-interactions become important.

Anton Rebhan

2008-10-15T23:59:59.000Z

102

Elliptic Flow from a Beam Energy Scan: a signature of a phase transition to the Quark-Gluon Plasma  

E-Print Network (OSTI)

We employ a relativistic transport theory to describe the fireball expansion of the matter created in ultra-relativistic heavy-ion collisions (uRHICs). Developing an approach to fix locally the shear viscosity to entropy density $\\eta/s$, we study the impact of a temperature dependent $\\eta/s(T)$ on the build-up of the elliptic flow, $v_2$, a measure of the angular anisotropy in the particle production. Beam Energy Scan from $\\sqrt{s_{NN}}= \\rm 62.4 GeV$ at RHIC up to 2.76 TeV at LHC has shown that the $v_2(p_T)$ as a function of the transverse momentum $p_T$ appears to be nearly invariant with energy. We show that such a surprising behavior is determined by a rise and fall of $\\eta/s(T)$ with a minimum at $T\\sim T_c$, as one would expect if the matter undergoes a phase transition or a cross-over. This provides an evidence for phase transition occurring in the uRHIC's and a first constraint on the temperature dependence of $\\eta/s$. In particular, a constant $\\eta/s$ at all temperatures or a too strong T-dependence would cause a breaking of the scaling of $v_2(p_T)$ with the energy.

S. Plumari; V. Greco; L. P. Csernai

2013-04-24T23:59:59.000Z

103

Anomalous Transport Processes in Turbulent non-Abelian Plasmas  

E-Print Network (OSTI)

Turbulent color fields, which can arise in the early and late stages of relativistic heavy ion collisions, may contribute significantly to the transport processes in the matter created in these collisions. We review the theory of these anomalous transport processes and discuss their possible phenomenology in the glasma and quasistationary expanding quark-gluon plasma.

Masayuki Asakawa; Steffen A. Bass; Berndt Müller

2010-08-20T23:59:59.000Z

104

Gluon distributions in nuclei probed at the CERN Large Hadron Collider  

E-Print Network (OSTI)

Using updated gluon distributions from global fits to data, we investigate the sensitivity of direct photoproduction of heavy quarks and exclusive production of vector mesons to varying strength of gluon modifications. Implications of using these processes for constraining nuclear gluon distributions are discussed.

Adeola Adeluyi; Carlos Bertulani

2011-04-21T23:59:59.000Z

105

Wake of a heavy quark in non-Abelian plasmas: Comparing kinetic theory and the anti-de Sitter space/conformal field theory correspondence  

E-Print Network (OSTI)

We compute the nonequilibrium stress tensor induced by a heavy quark moving through weakly coupled QCD plasma at the speed of light and compare the result to N=4 super-Yang-Mills theory at strong coupling. The QCD Boltzmann ...

Hong, Juhee

106

Electrical conductivity of quark matter at finite T  

E-Print Network (OSTI)

In this talk, I present the recent theoretical results on the electrical conductivity (EC) sigma of quark matter, using the Kubo formula at finite temperature and zero quark density (T>0, mu=0) in the presence of an external strong magnetic field. The dilute instanton-liquid model with the caloron distribution is taken into account. It turns out that sigma=(0.02~0.15)/fm for T=(0~400) MeV with the relaxation time tau=(0.3~0.9) fm. EC is parameterized as sigma/T (0.46,0.77,1.08,1.39)C_EM for tau=(0.3,0.5,0.7,0.9) fm, respectively. These results are well compatible with other theoretical estimations and show almost negligible effects from the magnetic field. The soft photon emission rate from the quark-gluon plasma is discussed as well.

Seung-il Nam

2012-10-30T23:59:59.000Z

107

Nucleation of quark matter in the PQM model  

SciTech Connect

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

Mintz, Bruno W. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21945-970 (Brazil); Stiele, Rainer; Schaffner-Bielich, Juergen [Institut fuer Theoretische Physik, Ruprecht-Karls-Universitaet, Philosophenweg 16, D-69120, Heidelberg, Germany and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Planckstrasse 1, D-64291 D (Germany); Ramos, Rudnei O. [Departamento de Fisica Teorica, Universidade do Estado do Rio de Janeiro, 20550-013 Rio de Janeiro, RJ (Brazil)

2013-03-25T23:59:59.000Z

108

Regge behaviour of distribution functions and evolution of gluon distribution function in Next-to-Leading order at low-x  

E-Print Network (OSTI)

Evolution of gluon distribution function from Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equation in next-to-leading order (NLO) at low-x is presented assuming the Regge behaviour of quarks and gluons at this limit. We compare our results of gluon distribution function with MRST2004, GRV98LO and GRV98NLO parameterizations and show the compatibility of Regge behaviour of quark and gluon distribution functions with perturbative quantum chromodynamics (PQCD) at low-x.

U. Jamil; J. K. Sarma

2007-12-01T23:59:59.000Z

109

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.

110

Accessing the Distribution of Linearly Polarized Gluons in Unpolarized Hadrons  

SciTech Connect

Gluons inside unpolarized hadrons can be linearly polarized provided they have a nonzero transverse momentum. The simplest and theoretically safest way to probe this distribution of linearly polarized gluons is through cos2{phi} asymmetries in heavy quark pair or dijet production in electron-hadron collisions. Future Electron-Ion Collider (EIC) or Large Hadron electron Collider (LHeC) experiments are ideally suited for this purpose. Here we estimate the maximum asymmetries for EIC kinematics.

Boer, Daniel; /Groningen, KVI; Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; Mulders, Piet J.; /Vrije U., Amsterdam; Pisano, Cristian; /Cagliari U. /INFN, Cagliari

2011-08-19T23:59:59.000Z

111

Chiral symmetry, massive gluons and confinement  

SciTech Connect

It is quite difficult to obtain non-trivial chiral symmetry breaking solutions for the quark gap equation in the presence of dynamically generated gluon masses. An effective confining propagator has recently been proposed by Cornwall in order to solve this problem. We study phenomenological consequences of this approach, showing its compatibility with the experimental data. We argue that this confining propagator should be restricted to a small region of momenta, leading to effective four-fermion interactions at low energy.

Natale, A. A. [Instituto de Fisica Teorica - UNESP Rua Dr. Bento T. Ferraz, 271, Bl.II - 01140-070, Sao Paulo, SP (Brazil)

2013-03-25T23:59:59.000Z

112

Quark-gluon correlations and Color Polarizabilities  

Science Conference Proceedings (OSTI)

We discuss the present status of the twist-3 matrix element in the spin srtructure of the nucleon and describe two proposed experiments that will improve on the precision of the present measurements of the twist-3 and twist-4 matrix elements for both the proton and the neutron and consequently will improve on our knowledge of the “color polarizabilitites” in the nucleon.

Zein-Eddine Meziani

2006-11-01T23:59:59.000Z

113

Fully nonlinear excitations of non-Abelian plasma  

E-Print Network (OSTI)

We investigate fully nonlinear, non-Abelian excitations of quark-antiquark plasma, using relativistic fluid theory in cold plasma approximation. There are mainly three important nonlinearities, coming from various sources such as non-Abelian interactions of Yang-Mills (YM) fields, Wong's color dynamics and plasma nonlinearity, in our model. By neglecting nonlinearities due to plasma and color dynamics we get back the earlier results of Blaizot {\\it et. al.}, Phys. Rev. Lett. 72, 3317 (1994). Similarly, by neglecting YM fields nonlinearity and plasma nonlinearity, it reduces to the model of Gupta {\\it et. al.}, Phys. Lett. B498, 223 (2005). Thus we have the most general non-Abelian mode of quark-gluon plasma (QGP). Further, our model resembles the problem of propagation of laser beam through relativistic plasma, Physica 9D, 96 (1983). in the absence of all non-Abelian interactions.

Vishnu M. Bannur

2007-06-06T23:59:59.000Z

114

Physics Out Loud - Gluons  

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

Elementary Particles Previous Video (Elementary Particles) Physics Out Loud Main Index Next Video (Hadron) Hadron Gluons Elena Long, A graduate student at Kent State University,...

115

Regge behaviour of distribution functions and t and x-evolutions of gluon distribution function at low-x  

E-Print Network (OSTI)

In this paper t and x-evolutions of gluon distribution function from Dokshitzer-Gribov-Lipatov-Altarelli-Parisi(DGLAP) evolution equation in leading order(LO) at low-x, assuming the Regge behaviour of quark and gluon at this limit, are presented. We compare our results of gluon distribution function with MRST 2001, MRST 2004 and GRV '98 parameterizations and show the compatibility of Regge behaviour of quark and gluon distribution functions with perturbative quantum chromodynamics(PQCD) at low-x. We also discuss the limitations of Taylor series expansion method used earlier to solve DGLAP evolution equations, in the Regge behaviour of distribution functions.

U. Jamil; J. K. Sarma

2005-08-05T23:59:59.000Z

116

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...

117

Nonzero Mean Squared Momentum of Quarks in the Non-Perturbative QCD Vacuum  

E-Print Network (OSTI)

The non-local vacuum condensates of QCD describe the distributions of quarks and gluons in the non-perturbative QCD vacuum. Physically, this means that vacuum quarks and gluons have nonzero mean-squared momentum, called virtuality. In this paper we study the quark virtuality which is given by the ratio of the local quark-gluon mixed vacuum condensate to the quark local vacuum condensate. The two vacuum condensates are obtained by solving Dyson-Schwinger Equations of a fully dressed quark propagator with an effective gluon propagator. Using our calculated condensates, we obtain the virtuality of quarks in the QCD vacuum state. Our numerical predictions differ from the other theoretical model calculations such as QCD sum rules, Lattice QCD and instanton models.

Zhou, Li-Juan; Ma, Wei-xing

2009-01-01T23:59:59.000Z

118

Gluon-fusion contributions to {Phi}+2 jet production  

Science Conference Proceedings (OSTI)

In high energy hadronic collisions, a scalar or pseudoscalar Higgs boson, {Phi}=H, A, can be efficiently produced via gluon fusion, which is mediated by heavy quark loops. In this paper, we consider double real emission corrections to {Phi}=A production, which lead to a Higgs plus two-jet final state, at order {alpha}{sub s}{sup 4}. Full quark mass effects are considered in the calculation of scattering amplitudes for the CP-odd Higgs boson A, as induced by quark triangle-, box-, and pentagon-diagrams. They complement the analogous results for a CP-even Higgs boson H in Ref. [1]. Interference effects between loops with top and bottom quarks as well as between CP-even and CP-odd couplings of the heavy quarks are fully taken into account.

Campanario, F.; Zeppenfeld, D. [Institut fuer Theoretische Physik, Universitaet Karlsruhe P. O. Box 6980 76128 Karlsruhe (Germany); Kubocz, M. [Institut fuer Theoretische Teilchenphysik und Kosmologie, RWTH Aachen University, D52056 Aachen (Germany)

2011-11-01T23:59:59.000Z

119

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...

120

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

Note: This page contains sample records for the topic "quark gluon plasma" 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.


121

Scaling behavior and positivity violation of the gluon propagator in full QCD  

SciTech Connect

The Landau-gauge gluon propagator is studied using the coarse and fine dynamical MILC configurations. The effects of dynamical quarks are clearly visible and lead to a reduction of the nonperturbative infrared enhancement relative to the quenched case. Lattice spacing effects are studied and found to be small. The gluon spectral function is shown to clearly violate positivity in both quenched and full QCD.

Bowman, Patrick O. [Centre of Theoretical Chemistry and Physics, Institute of Fundamental Sciences, Massey University (Auckland), Private Bag 102904, NSMSC, Auckland (New Zealand); Heller, Urs M. [American Physical Society, One Research Road, Box 9000, Ridge, New York 11961-9000 (United States); Leinweber, Derek B.; Sternbeck, Andre; Smekal, Lorenz von; Williams, Anthony G. [Special Research Center for the Subatomic Structure of Matter (CSSM), Department of Physics, University of Adelaide, Adelaide 5005 (Australia); Parappilly, Maria B. [Special Research Center for the Subatomic Structure of Matter (CSSM), Department of Physics, University of Adelaide, Adelaide 5005 (Australia); School of Chemistry, Physics and Earth Sciences, Flinders University, GPO Box 2100, Adelaide 5001 (Australia); Zhang Jianbo [Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

2007-11-01T23:59:59.000Z

122

The effect of partonic wind on charm quark correlations in high-energy nuclear collisions  

E-Print Network (OSTI)

In high-energy collisions, massive heavy quarks are produced back-to-back initially and they are sensitive to early dynamical conditions. The strong collective partonic wind from the fast expanding quark-gluon plasma created in high-energy nuclear collisions modifies the correlation pattern significantly. As a result, the angular correlation function for D$\\bar{\\rm D}$ pairs is suppressed at the angle $\\Delta\\phi=\\pi$. While the hot and dense medium in collisions at RHIC ($\\sqrt{s_{NN}}=200$ GeV) can only smear the initial back-to-back D$\\bar {\\rm D}$ correlation, a clear and strong near side D$\\bar{\\rm D}$ correlation is expected at LHC ($\\sqrt{s_{NN}}=5500$ GeV).

X. Zhu; N. Xu; P. Zhuang

2007-09-03T23:59:59.000Z

123

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

124

Jet acollinearity and quark form factors  

Science Conference Proceedings (OSTI)

Perturbative Quantum Chromodynamic corrections involving the emission of gluons which are both soft and collinear are discussed for both hadronic production of lepton pairs and e/sup +/e/sup -/ annihilation. The result is an exponential, double logarithmic quark form factor. The effect of sub-leading corrections and the possible experimental observation of the form factor are discussed.

Stirling, W.J.

1980-01-01T23:59:59.000Z

125

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

126

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

127

Gluon-gluon contributions to W+ W- production and Higgs interference effects  

Science Conference Proceedings (OSTI)

In this paper we complete our re-assessment of the production of W boson pairs at the LHC, by calculating analytic results for the gg {yields} W{sup +}W{sup -} {yields} {nu}{ell}{sup +}{ell}{sup -}{bar {nu}} process including the effect of massive quarks circulating in the loop. Together with the one-loop amplitudes containing the first two generations of massless quarks propagating in the loop, these diagrams can give a significant contribution with a large flux of gluons. One of the component parts of this calculation is the production of a standard model Higgs boson, gg {yields} H and its subsequent decay, H {yields} W{sup +}({yields} {nu}{ell}{sup +})W{sup -}({yields} {ell}{sup -}{bar {nu}}). We will quantify the importance of the interference between the Higgs boson production process and the gluon-induced continuum production in the context of searches for the Higgs boson at the Tevatron and the LHC. For instance, for m{sub H} < 140 GeV the effect of the interference typically results in around a 10% reduction in the expected number of Higgs signal events. The majority of this interference is due to non-resonant contributions. Therefore cuts on the transverse mass such as those currently used by the ATLAS collaboration reduce the destructive interference to about a 1% effect. We advocate that a cut on the maximum transverse mass be used in future Higgs searches in this channel.

Campbell, John M.; Ellis, R.Keith; Williams, Ciaran

2011-07-01T23:59:59.000Z

128

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

129

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...

130

Gluon-fusion Higgs production at NNLO for a non-standard Higgs sector  

SciTech Connect

We consider an extension of the Standard Model with an arbitrary number of heavy quarks having general couplings to the Higgs boson. We construct an effective Lagrangian integrating out quarks that are heavier than half the mass of the Higgs boson and compute the Wilson coefficient for the effective gluon-Higgs vertex through NNLO. We apply our result to a composite Higgs model with vector-like quarks coupling to the third generation quarks. In the heavy quark-mass approximation, we show that the suppression of the leading-order cross section with respect to the Standard Model does not depend on the number of vector-like multiplets introduced. We analyse the effects of QCD and electroweak corrections through three loops, as well as bottom-quark contributions through two loops.

Furlan E.

2011-10-24T23:59:59.000Z

131

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

132

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? ------------------------

133

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...

134

Holographic Photon Production with Magnetic Field in Anisotropic Plasmas  

E-Print Network (OSTI)

We investigate the thermal photon production from constant magnetic field in a strongly coupled and anisotropic plasma via the gauge/gravity duality. The dual geometry with pressure anisotropy is generated from the axion-dilaton gravity action introduced by Mateos and Trancancelli and the magnetic field is coupled to fundamental matters(quarks) through the D3/D7 embeddings. We find that the photon spectra with different quark mass are enhanced at large frequency when the photons are emitted parallel to the anisotropic direction with larger pressure or perpendicular to the magnetic field. However, in the opposite conditions for the emitted directions, the spectra approximately saturate isotropic results in the absence of magnetic field. On the other hand, a resonance emerges at moderate frequency for the photon spectrum with heavy quarks when the photons move perpendicular to the magnetic field. The resonance is more robust when the photons are polarized along the magnetic field. On the contrary, in the presence of pressure anisotropy, the resonance will be suppressed. There exist competing effects of magnetic field and pressure anisotropy on meson melting in the strongly coupled super Yang-Mills plasma, while we argue that the suppression led by anisotropy may not be applied to the quark gluon plasma.

Shang-Yu Wu; Di-Lun Yang

2013-05-23T23:59:59.000Z

135

Unburied Higgs boson: Jet substructure techniques for searching for Higgs' decay into gluons  

Science Conference Proceedings (OSTI)

Many models of physics beyond the standard model yield exotic Higgs decays. Some of these, particularly those in which the Higgs decays to light quarks or gluons, can be very difficult to discover experimentally. Here we introduce a new set of jet substructure techniques designed to search for such a Higgs when its dominant decay is into gluons via light, uncolored resonances. We study this scenario in both V+h and tt+h production channels, and find both channels lead to discovery at the LHC with > or approx. 5{sigma} at L{approx}100 fb{sup -1}.

Falkowski, Adam; Krohn, David; Wang Liantao; Shelton, Jessie; Thalapillil, Arun [NHETC and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States); Department of Physics, Princeton University, Princeton, New Jersey 08540 (United States); Department of Physics, Yale University, New Haven, Connecticut 06511 (United States); EFI and Department of Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637 (United States)

2011-10-01T23:59:59.000Z

136

Anomalies and asymmetries in quark-gluon matter  

SciTech Connect

The manifestations of axial anomaly and related effects in heavy-ion collisions are considered. Special role is played by various asymmetries. The azimuthal correlational asymmetries of neutron pairs at NICA/FAIR energy range may probe the global rotation of strongly interacting matter. The conductivity is related to the angular asymmetries of dilepton pairs. The strong magnetic field generated in heavy-ion collisions leads to the excess of soft dileptons flying predominantly in the scattering plane.

Teryaev, O. V., E-mail: teryaev@theor.jinr.ru [Joint Institute for Nuclear Research (Russian Federation)

2012-06-15T23:59:59.000Z

137

The Virtual photon-gluon impact factor with massive quarks and exact gluon kinematics.  

E-Print Network (OSTI)

that couples to the photon, at the top of the BFKL ladder. This is not the same as the Bjorken x variable, which corresponds to the bottom of the ladder. One may relate them using [8]: xg = x [(p ? (1? z)k)2 + Qˆ2 + kˆ2 +M2] Qˆ2 ; Qˆ2 = z(1? z)Q2, (4) From... + Qˆ2 +M2 ? (p ? k) (p? k)2 + Qˆ2 +M2 )2 +M2 ( 1 p2 + Qˆ2 +M2 ? 1 (p? k)2 + Qˆ2 +M2 )2} KN . (6) The kinematic factor KN = (Qˆ2)N [(p? (1 ? z)k)2 + Qˆ2 + kˆ2 +M2]N (7) in equations (5,6) is the same as in [5] up to the simple addition ofM2...

White, C D; Peschanski, Robert B; Thorne, Robert S

138

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

139

Kaluza-Klein gluon searches using the three-b-jet decay channel at the Large Hadron Collider  

E-Print Network (OSTI)

We study observability of a Kaluza-Klein (KK) excitation of a gluon in a five-dimensional model with a warped geometry at the Large Hadron Collider. In this model, the Standard Model fields reside in the bulk and the third generation quarks couple to the KK gluon strongly. We focus on the processes including three b-quarks as a final state where the first KK gluon propagates as an intermediate state. We evaluate a significance of those processes by taking account of kinematical cuts and a detector efficiency at the Large Hadron Collider and find that the significance is lager than 5-sigma with the integrated luminosity of 10 (100) fb^{-1} for a certain range of parameters of the model.

Masato Arai; Gi-Chol Cho; Karel Smolek

2013-07-24T23:59:59.000Z

140

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

Note: This page contains sample records for the topic "quark gluon plasma" 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.


141

Do Gluons Carry Proton Spin? - Toward Resolving the Spin Crisis (445th Brookhaven Lecture)  

Science Conference Proceedings (OSTI)

Just as Earth and other planets spin within the solar system, subatomic quark and gluon particles spin within the protons and neutrons that spin within the nucleus of an atom. Quantum Chromodynamics (QCD) is a theory that describes interactions between subatomic particles and it has played a defining role in understanding the spin of protons and neutrons, which make up most of the visible mass in the universe. Experiments first completed at CERN and furthered at several other laboratories around the world revealed that surprisingly, quarks and their partnering anti-quarks are responsible for only 20 to 30 percent of proton spin. These findings pointed to what would become known as "spin crisis." More recent experiments at BNL's Relativistic Heavy Ion Collider (RHIC), the first collider to smash protons that are "polarized," or made to spin in the same orientation, have helped to isolate the role of the gluon's spin within the spinning proton in hopes of resolving this crisis. In his lecture, Bazilevsky will explain how data from RHIC's PHENIX and STAR detectors help to reveal the role of gluons in the proton's spin. Bazilevsky will also discuss long- and short-term plans to attain a deeper look into the proton spin structure, utilizing RHIC and its future upgrades

Bazilevsky, Alexander (Physics Dept)

2009-01-21T23:59:59.000Z

142

Chemical Potential Dependence of Chiral Quark Condensate in Dyson-Schwinger Equation Approach of QCD  

E-Print Network (OSTI)

We propose a chemical potential dependent effective gluon propagator and study the chiral quark condensate in strongly interacting matter in the framework of Dyson-Schwinger equation approach. The obtained results manifest that, as the effect of the chemical potential on the effective gluon propagator is taken into account, the chiral quark condensate decreases gradually with the increasing of the chemical potential if it is less than the critical value, and the condensate vanishes suddenly at the critical chemical potential. The inclusion of the chemical potential in the effective gluon propagator enhances the decreasing rate and decreases the critical chemical potential. It indicates that the chiral symmetry can be restored completely at a critical chemical potential and restored partially as the chemical potential is less than the critical value. If the effective gluon propagator is independent of the chemical potential, the chiral symmetry can only be restored suddenly but no gradual restoration.

Lei Chang; Huan Chen; Bin Wang; Wei Yuan; Yu-xin Liu

2005-08-08T23:59:59.000Z

143

Strongly Correlated Quantum Fluids: Ultracold Quantum Gases, Quantum Chromodynamic Plasmas, and Holographic Duality  

E-Print Network (OSTI)

Strongly correlated quantum fluids are phases of matter that are intrinsically quantum mechanical, and that do not have a simple description in terms of weakly interacting quasi-particles. Two systems that have recently attracted a great deal of interest are the quark-gluon plasma, a plasma of strongly interacting quarks and gluons produced in relativistic heavy ion collisions, and ultracold atomic Fermi gases, very dilute clouds of atomic gases confined in optical or magnetic traps. These systems differ by more than 20 orders of magnitude in temperature, but they were shown to exhibit very similar hydrodynamic flow. In particular, both fluids exhibit a robustly low shear viscosity to entropy density ratio which is characteristic of quantum fluids described by holographic duality, a mapping from strongly correlated quantum field theories to weakly curved higher dimensional classical gravity. This review explores the connection between these fields, and it also serves as an introduction to the Focus Issue of New Journal of Physics on Strongly Correlated Quantum Fluids: from Ultracold Quantum Gases to QCD Plasmas. The presentation is made accessible to the general physics reader and includes discussions of the latest research developments in all three areas.

Allan Adams; Lincoln D. Carr; Thomas Schaefer; Peter Steinberg; John E. Thomas

2012-05-23T23:59:59.000Z

144

Gluon Fusion Processes at One-loop within the Standard Model and Beyond  

E-Print Network (OSTI)

In this thesis, we have studied certain gluon fusion processes which proceed via quark loop diagrams at the leading order. The fact that these gluon-gluon channel processes are independent processes, their contributions towards the total/differential hadronic cross sections can be calculated separately. We have considered the production of a pair of electroweak vector bosons in association with a jet via gluon fusion within the standard model. These processes were not accessible at earlier hadron colliders such as the Tevatron. Therefore, observation of these rare processes at the LHC will be a test of the standard model itself. Like the di-vector boson production via gluon fusion processes, these processes are also important backgrounds for many new physics signals, and the standard model Higgs boson signal at the LHC. These leading order gluon fusion processes contribute to the corresponding hadronic processes at the next-to-next-to-leading order in {\\alpha}_s. We have taken a model of extra-dimensions, the ADD (Arkani-Hamed, Dimopoulos and Dvali) model, as the possible candidate of new physics at the LHC. This model tries to solve the hierarchy problem of the standard model by proposing large extra space dimensions which may be accessible at TeV scale. We have considered the direct production of KK-gravitons (GKK) in association with an electroweak boson (H/{\\gamma}/Z) via gluon fusion. These processes contribute to the corresponding hadronic processes at the next-to-leading order in {\\alpha}_s. Many interesting issues related to the fermion loop amplitudes have also been discussed.

Ambresh Shivaji

2013-05-21T23:59:59.000Z

145

Heavy-quark production at large rapidities at hadron colliders.  

E-Print Network (OSTI)

to those partonic subprocesses that feature a gluon exchange in the t-channel; this happens for gg ? QQ¯g and qg ? QQ¯q, and it is peculiar to the NLO computations of quark pair production, as opposed to Born-level predictions, in which only fermions... -energy limit is QQ¯+1 jet production. In this case the partonic subprocesses gg ? QQ¯g and qg ? QQ¯q, which feature a gluon exchange in the t-channel, are O(?3S) at the Born level. This can also be considered as a reformulation of the standard Mueller...

Andersen, Jeppe R; Del Duca, Vittoria; Frixione, Stefano; Maltoni, Fabio; Stirling, W James

146

Recent PQCD calculations of heavy quark production  

E-Print Network (OSTI)

We summarize the results of a recent study of heavy quark production and attenuation in cold nuclear matter. In p+p collisions, we investigate the relative contribution of partonic sub-processes to $D$ meson production and $D$ meson-triggered inclusive di-hadrons to lowest order in perturbative QCD. While gluon fusion dominates the creation of large angle $D\\bar{D}$ pairs, charm on light parton scattering determines the yield of single inclusive $D$ mesons. The distinctly different non-perturbative fragmentation of $c$ quarks into $D$ mesons versus the fragmentation of quarks and gluons into light hadrons results in a strong transverse momentum dependence of anticharm content of the away-side charm-triggered jet. In p+A reactions, we calculate and resum the coherent nuclear-enhanced power corrections from the final-state partonic scattering in the medium. We find that single and double inclusive open charm production can be suppressed as much as the yield of neutral pions from dynamical high-twist shadowing. Effects of energy loss in p+A collisions are also investigated in the incoherent Bertsch-Gunion limit and may lead to significantly weaker transverse momentum dependence of the nuclear attenuation.

Ivan Vitev

2006-05-30T23:59:59.000Z

147

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....

148

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...

149

Exploration of hyperfine interaction between constituent quarks via eta productions  

E-Print Network (OSTI)

In this work, the different exchange freedom, one gluon, one pion or Goldstone boson, in constituent quark model is investigated, which is responsible to the hyperfine interaction between constituent quarks, via the combined analysis of the eta production processes, $\\pi^{-}p\\rightarrow\\eta n$ and $\\gamma p\\rightarrow\\eta p$. With the Goldstone-boson exchange, as well as the one-gluon or one-pion exchange, both the spectrum and observables, such as, the differential cross section and polarized beam asymmetry, are fitted to the suggested values of Particle Data Group and the experimental data. The first two types of exchange freedoms give acceptable description of the spectrum and observables while the one pion exchange can not describe the observables and spectrum simultaneously, so can be excluded. The experimental data for the two processes considered here strongly support the mixing angles for two lowest S11 sates and D13 states as about -30 and 6 degree respectively.

Jun He; S. G. Yuan; H. S. Xu

2011-05-09T23:59:59.000Z

150

Integral equation for gauge invariant quark Green's function  

E-Print Network (OSTI)

We consider gauge invariant quark two-point Green's functions in which the gluonic phase factor follows a skew-polygonal line. Using a particular representation for the quark propagator in the presence of an external gluon field, functional relations between Green's functions with different numbers of segments of the polygonal lines are established. An integral equation is obtained for the Green's function having a phase factor along a single straight line. The related kernels involve Wilson loops with skew-polygonal contours and with functional derivatives along the sides of the contours.

H. Sazdjian

2008-06-20T23:59:59.000Z

151

Universitair focusgebied: Foundations of Science  

E-Print Network (OSTI)

accelerators worldwide. The field of quark-gluon-plasma research attracts a lot of attention in the research

Utrecht, Universiteit

152

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

153

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

154

Ginzburg-Landau equations for superconducting quark matter in neutron stars  

E-Print Network (OSTI)

We investigate magnetic properties of color superconducting quark matter within a Ginzburg-Landau approach. The simultaneous coupling of the quark fields to gluonic and electromagnetic gauge fields leads to rotated electromagnetism with a massive (Higgsed) and a massless photon-gluon field. We derive the Ginzburg-Landau equations for superconducting quark matter taking into account the rotated electromagnetism in the general case when the rotation angle is an arbitrary function of the coordinates. We solve these equations for an isolated vortex in superconducting quark matter. We obtain a solution for the magnetic and gluomagnetic fields and expressions for the calculation of the penetration depth and the quantized magnetic flux in quark matter. For this case we have demonstrated that the occurence of electric and color Meissner currents is a consequence of the color superconducting state of quark matter.

D. Blaschke; D. Sedrakian

2000-06-19T23:59:59.000Z

155

Electric and magnetic screenings of gluons in a model with dimension-2 gluon condensate  

E-Print Network (OSTI)

Electric and magnetic screenings of the thermal gluons are studied by using the background expansion method in a gluodynamic model with dimension-2 gluon condensate. At low temperature, the electric and magnetic gluons are degenerate. With the increasing of temperature, it is found that the electric and magnetic gluons start to split at certain temperature $T_0$. The electric screening mass changes rapidly with temperature when $T>T_0$, and the Polyakov loop expectation value rises sharply around $T_0$ from zero in the vacuum to a value around 0.8 at high temperature. This suggests that the color electric deconfinement phase transition is driven by electric gluons. It is also observed that the magnetic screening mass keeps almost the same as its vacuum value, which manifests that the magnetic gluons remains confined. Both the screening masses and the Polyakov loop results are qualitatively in agreement with the Lattice calculations.

Fukun Xu; Mei Huang

2011-11-22T23:59:59.000Z

156

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

157

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...

158

Murray Gell-Mann, the Eightfold Way, Quarks, and Quantum Chromodynamics  

Office of Scientific and Technical Information (OSTI)

Murray Gell-Mann, the Eightfold Way, and Quantum Chromodynamics Murray Gell-Mann, the Eightfold Way, and Quantum Chromodynamics Resources with Additional Information Murray Gell-Mann Courtesy of the Santa Fe Institute 'In 1969, Professor Gell-Mann received the Nobel Prize in physics for his work on the theory of elementary particles. Professor Gell-Mann's "eightfold way" theory brought order to the chaos created by the discovery of some 100 particles in the atom's nucleus. Then he found that all of those particles, including the neutron and proton, are composed of fundamental building blocks that he named "quarks." The quarks are permanently confined by forces coming from the exchange of "gluons." He and others later constructed the quantum field theory of quarks and gluons, called "quantum chromodynamics," which seems to account for all the nuclear particles and their strong interactions." ...

159

Higgs boson plus photon production at the LHC: a clean probe of the b-quark parton densities  

E-Print Network (OSTI)

Higgs boson production in association with a high pT photon at the CERN Large Hadron Collider is analyzed, in the framework of the MSSM model, for the heavier neutral Higgs bosons. The request of an additional photon in the exclusive Higgs boson final state selects b-quark pairs among the possible initial partonic states, since gluon-gluon initial states are not allowed by C-parity conservation. Hence, the measurement of cross sections for neutral Higgs boson plus photon production can provide a clean probe of the b-quark density in the proton as well as of the b-quark Yukawa coupling. The suppression of the production rates by the b-quark electromagnetic coupling can be compensated by the enhanced Higgs boson Yukawa coupling to b's in the large tan(beta) regime. The Higgs boson decay into a tau-lepton pair is considered, and irreducible backgrounds with corresponding signal significances are evaluated.

Emidio Gabrielli; Barbara Mele; Johan Rathsman

2007-07-05T23:59:59.000Z

160

Remarks on double Higgs boson production by gluon fusion at threshold  

E-Print Network (OSTI)

The amplitude of double Higgs boson production by the gluon fusion, $gg \\to hh$, is known to be small due to cancellation between the graphs with the boson trilinear coupling and those with the coupling to the top quark. For this reason a study of this process was suggested as a sensitive probe of the Higgs sector nonlinearity. We calculate in a closed analytical form this amplitude at the threshold of the two bosons, where the cancellation is the strongest, and discuss the origin of the small value of the amplitude. We also note that the cancellation in the double boson production is in fact a part of a more general phenomenon of suppression of similar threshold amplitudes for multiple boson production, which, although not directly relevant to the actual top quark and the Higgs boson, can be useful in other studies.

Xin Li; M. B. Voloshin

2013-11-20T23:59:59.000Z

Note: This page contains sample records for the topic "quark gluon plasma" 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

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

162

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 -...

163

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 -...

164

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...

165

Charm and Beauty in a Hot Environment  

E-Print Network (OSTI)

We discuss the spectral analysis of quarkonium states in a hot medium of deconfined quarks and gluons, and we show that such an analysis provides a way to determine the thermal properties of the quark-gluon plasma.

Helmut Satz

2006-02-28T23:59:59.000Z

166

Shear Viscosity in a CFL Quark Star  

E-Print Network (OSTI)

We compute the mean free path and shear viscosity in the color-flavor locked (CFL) phase of dense quark matter at low temperature T, when the contributions of mesons, quarks and gluons to the transport coefficients are Boltzmann suppressed. CFL quark matter displays superfluid properties, and transport phenomena in such cold regime are dominated by phonon-phonon scattering. We study superfluid phonons within thermal field theory and compute the mean free path associated to their most relevant collision processes. Small-angle processes turn out to be more efficient in slowing transport phenomena in the CFL matter, while the mean free path relevant for the shear viscosity is less sensitive to collinear scattering due to the presence of zero modes in the Boltzmann equation. In analogy with superfluid He4, we find the same T power law for the superfluid phonon damping rate and mean free path. Our results are relevant for the study of rotational properties of compact stars, and correct wrong estimates existing in the literature.

Cristina Manuel; Antonio Dobado; Felipe J. Llanes-Estrada

2004-06-04T23:59:59.000Z

167

Gluon Condensate in Pion Superfluid beyond Mean Field Approximation  

E-Print Network (OSTI)

We study gluon condensate in a pion superfluid, through calculating the equation of state of the system in the Nambu-Jona-Lasinio model. While in mean field approximation the growing pion condensate leads to an increasing gluon condensate, meson fluctuations reduce the gluon condensate and the broken scalar symmetry can be smoothly restored at finite isospin density.

Yin Jiang; Pengfei Zhuang

2010-12-10T23:59:59.000Z

168

A General Effective Action for Quark Matter and its Application to Color Superconductivity  

E-Print Network (OSTI)

I derive a general effective theory for hot and/or dense quark matter. After introducing general projection operators for hard and soft quark and gluon degrees of freedom, I explicitly compute the functional integral for the hard quark and gluon modes in the QCD partition function. Upon appropriate choices for the projection operators one recovers various well-known effective theories such as the Hard Thermal Loop/ Hard Dense Loop Effective Theories as well as the High Density Effective Theory by Hong and Schaefer. I then apply the effective theory to cold and dense quark matter and show how it can be utilized to simplify the weak-coupling solution of the color-superconducting gap equation. In general, one considers as relevant quark degrees of freedom those within a thin layer of width 2 Lambda_q around the Fermi surface and as relevant gluon degrees of freedom those with 3-momenta less than Lambda_gl. It turns out that it is necessary to choose Lambda_q << Lambda_gl, i.e., scattering of quarks along the Fermi surface is the dominant process. Moreover, this special choice of the two cutoff parameters Lambda_q and Lambda_gl facilitates the power-counting of the numerous contributions in the gap-equation. In addition, it is demonstrated that both the energy and the momentum dependence of the gap function has to be treated self-consistently in order to determine the imaginary part of the gap function. For quarks close to the Fermi surface the imaginary part is calculated explicitly and shown to be of sub-subleading order in the gap equation.

Philipp T. Reuter

2006-02-13T23:59:59.000Z

169

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

170

Soft-gluon expansions through NNNLO  

SciTech Connect

I present universal master formulas for soft-gluon corrections to hard-scattering cross sections through next-to-next-to-next-to-leading order (NNNLO). I also briefly discuss applications to some processes where these corrections enhance the cross section and decrease the scale dependence.

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

2005-10-06T23:59:59.000Z

171

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

172

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

173

–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

174

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...

175

–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

176

–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

177

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

178

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...

179

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

180

Electric Flux Tube in Magnetic Plasma  

E-Print Network (OSTI)

In this paper we study a methodical problem related to the magnetic scenario recently suggested and initiated by the authors \\cite{Liao_ES_mono} to understand the strongly coupled quark-gluon plasma (sQGP): the electric flux tube in monopole plasma. A macroscopic approach, interpolating between Bose condensed (dual superconductor) and classical gas medium is developed first. Then we work out a microscopic approach based on detailed quantum mechanical calculation of the monopole scattering on electric flux tube, evaluating induced currents for all partial waves. As expected, the flux tube looses its stability when particles can penetrate it: we make this condition precise by calculating the critical value for the product of the flux tube size times the particle momentum, above which the flux tube dissolves. Lattice static potentials indicate that flux tubes seem to dissolve at $T>T_{dissolution} \\approx 1.3 T_c$. Using our criterion one gets an estimate of the magnetic density $n\\approx 4.4 \\sim 6.6 fm^{-3}$ a...

Liao Jin Feng

2007-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "quark gluon plasma" 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.


181

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...

182

Relativistic shock waves in viscous gluon matter  

E-Print Network (OSTI)

We solve the relativistic Riemann problem in viscous gluon matter employing a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio $\\eta/s$ from zero to infinity. We show that an $\\eta/s$ ratio larger than 0.2 prevents the development of well-defined shock waves on timescales typical for ultrarelativistic heavy-ion collisions. Comparisons with viscous hydrodynamic calculations confirm our findings.

I. Bouras; E. Molnar; H. Niemi; Z. Xu; A. El; O. Fochler; C. Greiner; D. H. Rischke

2009-02-11T23:59:59.000Z

183

The Gluon Green's Function at Small x  

E-Print Network (OSTI)

In this contribution a recently proposed iterative procedure is used to study the BFKL gluon Green's function at next-to-leading order. This is done in QCD and in N=4 supersymmetric Yang-Mills theory. The study includes an analysis of the evolution with energy and of angular dependences. A discussion of a novel resummation of running coupling terms in the QCD case is included.

Agustin Sabio Vera

2004-08-01T23:59:59.000Z

184

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

185

Challenges to quantum chromodynamics: Anomalous spin, heavy quark, and nuclear phenomena  

SciTech Connect

The general structure of QCD meshes remarkably well with the facts of the hadronic world, especially quark-based spectroscopy, current algebra, the approximate point-like structure of large momentum transfer inclusive reactions, and the logarithmic violation of scale invariance in deep inelastic lepton-hadron reactions. QCD has been successful in predicting the features of electron-positron and photon-photon annihilation into hadrons, including the magnitude and scaling of the cross sections, the shape of the photon structure function, the production of hadronic jets with patterns conforming to elementary quark and gluon subprocesses. The experimental measurements appear to be consistent with basic postulates of QCD, that the charge and weak currents within hadrons are carried by fractionally-charged quarks, and that the strength of the interactions between the quarks, and gluons becomes weak at short distances, consistent with asymptotic freedom. Nevertheless in some cases, the predictions of QCD appear to be in dramatic conflict with experiment. The anomalies suggest that the proton itself as a much more complex object than suggested by simple non-relativistic quark models. Recent analyses of the proton distribution amplitude using QCD sum rules points to highly-nontrival proton structure. Solutions to QCD in one-space and one-time dimension suggest that the momentum distributions of non-valence quarks in the hadrons have a non-trival oscillatory structure. The data seems also to be suggesting that the intrinsic'' bound state structure of the proton has a non- negligible strange and charm quark content, in addition to the extrinsic'' sources of heavy quarks created in the collision itself. 144 refs., 46 figs., 2 tabs.

Brodsky, S.J.

1989-11-01T23:59:59.000Z

186

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

187

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

188

Next-to-next-to-next-to-leading-order soft-gluon corrections in hard-scattering processes near threshold  

SciTech Connect

I present a unified calculation of soft-gluon corrections to hard-scattering cross sections through next-to-next-to-next-to-leading order (NNNLO). Master formulas are derived, from a threshold resummation formalism, that can be applied to total and differential cross sections for hard-scattering processes in hadron colliders. I also present numerical results for charged Higgs production at the LHC where these corrections are large, and for top quark production at the Tevatron where these corrections greatly reduce the scale dependence of the cross section.

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

2006-02-01T23:59:59.000Z

189

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,

190

Universality of Unintegrated Gluon Distributions at small x  

Science Conference Proceedings (OSTI)

We systematically study dijet production in various processes in the small-x limit and establish an effective kt-factorization for hard processes in a system with dilute probes scattering on a dense target. In the large-Nc limit, the unintegrated gluon distributions involved in different processes are shown to be related to two widely proposed ones: the Weizsacker-Williams gluon distribution and the dipole gluon distribution.

Dominguez, Fabio; Marquet, Cyrille; Xiao, Bowen; Yuan, Feng

2011-01-04T23:59:59.000Z

191

A New Approach to the Gluon Structure Function  

E-Print Network (OSTI)

We calculate the gluon structure function of a color dipole in a new approach evaluating the matrix elements of SU(2) gluon field operators separated along a direction close to the light cone. As vacuum state in the pure glue sector, we use a variational ground state of the near-light-cone Hamiltonian. With a mean momentum fraction of the gluons fixed to the "experimental value" in a proton, the resulting gluon structure function for a dipole state with four links is compared qualitatively to the NLO \\emph{MRST} 2002 parameterization at $Q^2=1.5 \\mathrm{GeV}^2$.

D. Grünewald; E. -M. Ilgenfritz; H. J. Pirner

2009-11-05T23:59:59.000Z

192

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

193

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

194

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...

195

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

196

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....

197

Higgs Production by Gluon initiated Weak Boson Fusion  

E-Print Network (OSTI)

The gluon-gluon induced terms for Higgs production through weak-boson fusion are calculated. They form a finite and gauge-invariant subset of the NNLO corrections in the strong coupling constant. This is also the lowest order with sizeable t-channel colour exchange contributions, leading to additional hadronic activity between the outgoing jets.

M. M. Weber

2007-09-17T23:59:59.000Z

198

Molecular dynamics simulation of strongly coupled QCD plasmas  

E-Print Network (OSTI)

The properties of a strongly interacting quark plasma are investigated by molecular dynamics method including non-abelian quark-quark potential. Our main goal is to study the thermalization process in this system. We find an interesting resonance-like behaviour: at a characteristic time close to the inverse plasma frequency the quark plasma is heated up substantially via energy transfer from quark potential energy into one particle kinetic energy. Color rotation mechanism enhances the effectivity of this heating process, leading to a very fast thermalization with high temperature.

P. Hartmann; Z. Donko; P. Levai; G. J. Kalman

2006-01-06T23:59:59.000Z

199

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

200

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

Note: This page contains sample records for the topic "quark gluon plasma" 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.


201

Quark helicity flip and the transverse spin dependence of inclusive DIS  

SciTech Connect

Inclusive DIS with unpolarized beam exhibits a subtle dependence on the transverse target spin, arising from the interference of one-photon and two-photon exchange amplitudes in the cross section. We argue that this observable probes mainly the quark helicity-flip amplitudes induced by the non-perturbative vacuum structure of QCD (spontaneous chiral symmetry breaking). This conjecture is based on (a) the absence of significant Sudakov suppression of the helicity-flip process if soft gluon emission in the quark subprocess is limited by the chiral symmetry breaking scale mu^2_{chiral} >> Lambda^2_{QCD}; (b) the expectation that the quark helicity-conserving twist-3 contribution is small. The normal target spin asymmetry is estimated to be of the order 10^{-4} in the kinematics of the planned Jefferson Lab Hall A experiment.

Andrei Afanasev; Mark Strikman; Christian Weiss

2007-05-21T23:59:59.000Z

202

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

203

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,...

204

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...

205

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

206

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

207

The study of quark-gluon matter in high-energy nucleus-nucleus collisions  

SciTech Connect

A short overview is given on the study of hot matter produced in relativistic nucleusnucleus collisions, with emphasis on recent measurements at the LHC.

Andronic, A. [Reasearch Division and EMMI, GSI Helmholtzzentrum fuer Schwerionenforschung, D-64291 Darmstadt (Germany)

2012-11-20T23:59:59.000Z

208

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

209

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

210

Page not found | Department of Energy  

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

Quark Gluon Plasma, Solar-Power Generating Windows and CCS Field Studies Large Hadron Collider's (LHC) first record-setting run of high-energy proton collisions,...

211

DLMF: Index Q  

Science Conference Proceedings (OSTI)

... quantum wave-packets: theta functions §20.13. quark-gluon plasma: Bernoulli polynomials §24.18. quartic equations ¶ ? §1.11 ...

2013-05-03T23:59:59.000Z

212

DLMF: §24.18 Physical Applications  

Science Conference Proceedings (OSTI)

... forces ( Li et al. (1991) ), and in a study of quark-gluon plasma ( Meisinger et al. (2002) ). Euler polynomials also appear ...

2013-05-03T23:59:59.000Z

213

Fullset(HEDP-Sept20).pmd  

National Nuclear Security Administration (NNSA)

Nuclear Physics: This category recognizes the distinct nature of quark- gluon plasma research and its foundations in the broader field of nuclear physics. At normal...

214

Distribution of linearly polarized gluons inside a large nucleus  

E-Print Network (OSTI)

The distribution of linearly polarized gluons inside a large nucleus is studied in the framework of the color glass condensate. We find that the Weizs\\"acker-Williams distribution saturates the positivity bound at large transverse momenta and is suppressed at small transverse momenta, whereas the dipole distribution saturates the bound for any value of the transverse momentum. We also discuss processes in which both distributions of linearly polarized gluons can be probed.

Andreas Metz; Jian Zhou

2011-05-10T23:59:59.000Z

215

Detecting a Higgs Pseudoscalar with a Z Boson Produced in Bottom Quark Fusion  

E-Print Network (OSTI)

We investigate the prospects of detecting a Higgs pseudoscalar ($A^0$) in association with a $Z$ gauge boson produced from bottom quark fusion ($b\\bar{b} \\to ZA^0$) at the CERN Large Hadron Collider (LHC). A general two Higgs doublet model and the minimal supersymmetric standard model are adopted to study the discovery potential of $pp \\to ZA^0 \\to \\ell \\bar{\\ell} b\\bar{b} +X (\\ell = e, \\mu)$, via $b\\bar{b} \\to ZA^0$ with physics backgrounds and realistic cuts. Promising results are found for $m_A \\alt 400$ GeV in a general two Higgs doublet model when the heavier Higgs scalar ($H^0$) can decay into a $Z$ boson and a Higgs pseudoscalar ($H^0 \\to ZA^0$). We compare the production rates from bottom quark fusion ($b\\bar{b} \\to ZA^0$) and gluon fusion ($gg \\to ZA^0$) and find that they are complementary processes to produce $ZA^0$ in hadron collisions. While gluon fusion is the major source for producing a Higgs pseudoscalar associated with a $Z$ boson at the LHC for $\\tan\\beta \\alt 10$, bottom quark fusion can make dominant contributions for $\\tan\\beta \\agt 10$.

Chung Kao; Shankar Sachithanandam

2004-11-24T23:59:59.000Z

216

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

217

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

218

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...

219

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

220

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...

Note: This page contains sample records for the topic "quark gluon plasma" 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.


221

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...

222

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...

223

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

224

Relativistic Shock Waves and Mach Cones in Viscous Gluon Matter  

E-Print Network (OSTI)

To investigate the formation and the propagation of relativistic shock waves in viscous gluon matter we solve the relativistic Riemann problem using a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio $\\eta/s$. Furthermore we compare our results with those obtained by solving the relativistic causal dissipative fluid equations of Israel and Stewart (IS), in order to show the validity of the IS hydrodynamics. Employing the parton cascade we also investigate the formation of Mach shocks induced by a high-energy gluon traversing viscous gluon matter. For $\\eta/s = 0.08$ a Mach cone structure is observed, whereas the signal smears out for $\\eta/s \\geq 0.32$.

Ioannis Bouras; Etele Molnár; Harri Niemi; Zhe Xu; Andrej El; Oliver Fochler; Francesco Lauciello; Carsten Greiner; Dirk H. Rischke

2010-04-26T23:59:59.000Z

225

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

226

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

227

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

228

Heavy quark production in photon-Pomeron interactions at high energies  

Science Conference Proceedings (OSTI)

The diffractive heavy quark cross sections are estimated considering photon-Pomeron interactions in hadron - hadron at RHIC, Tevatron, and CERN LHC energies. We assume the validity of the hard diffractive factorization and calculate the charm and bottom total cross sections and rapidity distributions using the diffractive parton distribution functions of the Pomeron obtained by the H1 Collaboration at DESY-HERA. Such processes are sensitive to the gluon content of the Pomeron at high energies and are a good place to constrain the behavior of this distribution. We also compare our predictions with those obtained using the dipole model, and verify that these processes are a good test of the different mechanisms for heavy quarks diffractive production at hadron colliders.

Machado, M. M. [Instituto Federal de Ciencia, Educacao e Tecnologia Farroupilha, Campus Sao Borja, Rua Otaviano Castilho Mendes, 355, CEP 97670-000, Sao Borja, RS (Brazil); Goncalves, V. P. [Instituto de Fisica e Matematica - IFM, Universidade Federal de Pelotas, Caixa Postal 354, CEP 96010-900, RS (Brazil)

2013-03-25T23:59:59.000Z

229

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

230

Two-loop corrections to gluon fusion into two photons  

SciTech Connect

An overview of the calculation of the two-loop helicity amplitudes for scattering of two gluons into two photons is presented. These matrix elements enter into the recent improved calculation of the QCD background to Higgs boson decay into a pair of photons, which is the preferred search mode at the LHC for the case of a light Higgs boson.

Dixon, Lance

2002-12-20T23:59:59.000Z

231

Higher twists in polarized DIS and the size of the constituent quark  

SciTech Connect

The spontaneous breaking of chiral symmetry implies the presence of a short-distance scale in the QCD vacuum, which phenomenologically may be associated with the ''size'' of the constituent quark, rho {approx} 0.3 fm. We discuss the role of this scale in the matrix elements of the twist-4 and 3 quark-gluon operators determining the leading power (1/Q{sup 2}-) corrections to the moments of the nucleon spin structure functions. We argue that the flavor-nonsinglet twist-4 matrix element, f{sub 2}{sup u-d}, has a sizable negative value of the order rho{sup -2}, due to the presence of sea quarks with virtualities {approx} rho{sup -2} in the proton wave function. The twist-3 matrix element, d{sub 2}, is not related to the scale rho{sup -2}. Our arguments support the results of previous calculations of the matrix elements in the instanton vacuum model. We show that this qualitative picture is in agreement with the phenomenological higher-twist correction extracted from an NLO QCD fit to the world data on g{sub 1}{sup p} and g{sub 1}{sup n}, which include recent data from the Jefferson Lab Hall A and COMPASS experiments. We comment on the implications of the short-distance scale rho for quark-hadron duality and the x-dependence of higher-twist contributions.

Alexander Sidorov; Christian Weiss

2006-02-15T23:59:59.000Z

232

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

233

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

234

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...

235

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...

236

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

237

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

238

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

239

Working group report: Quantum chromodynamics - Springer  

Science Conference Proceedings (OSTI)

(quark/anti-quark) and for Higgs production through gluon fusion, I = g (gluon) and for bottom quark annihilation to Higgs boson, I = b (bottom quark). Here. ?I.

240

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

Note: This page contains sample records for the topic "quark gluon plasma" 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

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

242

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...

243

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

244

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

245

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

246

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

247

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

248

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

249

The Gluon Green's function in the BFKL approach at next-to-leading logarithmic accuracy.  

E-Print Network (OSTI)

, University of Cambridge, Madingley Road, CB3 0HE, Cambridge, UK bDAMTP, Centre for Mathematical Sciences, Wilberforce Road, CB3 0WA, Cambridge, UK Abstract We investigate the gluon Green’s function in the high energy limit of QCD using a recently proposed... –independent gluon Green’s function. This gluon Green’s function de- scribes the interaction between two Reggeised gluons exchanged in the t– channel with transverse momenta ka,b, and it carries the energy dependence of the cross–section. We choose to work...

Andersen, Jeppe R; Sabio Vera, Agustin

250

Higgs production via gluon fusion in association with two or three jets in supersymmetric models.  

E-Print Network (OSTI)

??Within the MSSM neutral Higgs bosons can be efficiently produced via gluon fusion in high energy hadronic collisions. Real emission corrections to Higgs production can… (more)

Kubocz, Michael

2009-01-01T23:59:59.000Z

251

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

252

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

253

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

254

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

255

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

256

A Study of the gluon ladder in diffractive processes.  

E-Print Network (OSTI)

of iterations of its kernel directly in transverse momentum and rapidity space. Several studies of the non–forward solution are performed both at the level of the gluon Green’s function and for a toy cross–section, including an analysis of the diffusion... - sponding kernel is available. ?e-mail: andersen@hep.phy.cam.ac.uk †e-mail: sabio@mail.desy.de ‡Alexander von Humboldt Research Fellow 1 1 Introduction An interesting framework to study the behaviour of QCD scattering amplitudes in the limit of large centre...

Andersen, Jeppe R; Sabio Vera, Agustin

257

Gluon distribution functions and Higgs boson production at moderate transverse momentum  

Science Conference Proceedings (OSTI)

We investigate the gluon distribution functions and their contributions to the Higgs boson production in pp collisions in the transverse momentum-dependent factorization formalism. In addition to the usual azimuthal symmetric transverse momentum-dependent gluon distribution, we find that the azimuthal correlated gluon distribution also contributes to the Higgs boson production. This explains recent findings on the additional contribution in the transverse momentum resummation for the Higgs boson production as compared to that for electroweak boson production processes. We further examine the small-x naive k{sub t}-factorization in the dilute region and find that the azimuthal correlated gluon distribution contribution is consistently taken into account. The result agrees with the transverse momentum-dependent factorization formalism. We comment on the possible breakdown of the naive k{sub t}-factorization in the dense medium region, due to the unique behaviors for the gluon distributions.

Sun Peng [Center for High Energy Physics, Peking University, Beijing 100871 (China); Xiao Bowen [Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Yuan Feng [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Center for High Energy Physics, Peking University, Beijing 100871 (China); RIKEN BNL Research Center, Building 510A, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2011-11-01T23:59:59.000Z

258

Gluon distribution functions and Higgs boson production at moderate transverse momentum  

Science Conference Proceedings (OSTI)

We investigate the gluon distribution functions and their contributions to the Higgs boson production in pp collisions in the transverse momentum-dependent factorization formalism. In addition to the usual azimuthal symmetric transverse momentum-dependent gluon distribution, we find that the azimuthal correlated gluon distribution also contributes to the Higgs boson production. This explains recent findings on the additional contribution in the transverse momentum resummation for the Higgs boson production as compared to that for electroweak boson production processes. We further examine the small-x naive kt-factorization in the dilute region and find that the azimuthal correlated gluon distribution contribution is consistently taken into account. The result agrees with the transverse momentum-dependent factorization formalism. We comment on the possible breakdown of the naive kt-factorization in the dense medium region, due to the unique behaviors for the gluon distributions.

Sun P.; Yuan F.; Xiao, B.W.

2011-11-04T23:59:59.000Z

259

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

260

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

Note: This page contains sample records for the topic "quark gluon plasma" 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

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

262

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

263

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

264

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

265

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

266

A Colorful Wake for Gerhard Soff  

E-Print Network (OSTI)

We calculate the wake induced in a hot QCD plasma by a fast parton in the framework of linear response theory. We discuss two scenarios: ($i$) a weakly coupled quark-gluon plasma described by hard-thermal loop perturbation theory and ($ii$) a strongly coupled quark-gluon plasma which resembles a quantum liquid. We show that a Mach cone can appear in the second scenario, but not in the first one

Berndt Müller; Jörg Ruppert

2005-07-18T23:59:59.000Z

267

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

268

Gluon Regge trajectory at two loops from Lipatov's high energy effective action  

E-Print Network (OSTI)

We present the derivation of the two-loop gluon Regge trajectory using Lipatov's high energy effective action and a direct evaluation of Feynman diagrams. Using a gauge invariant regularization of high energy divergences by deforming the light-cone vectors of the effective action, we determine the two-loop self-energy of the reggeized gluon, after computing the master integrals involved using the Mellin-Barnes representations technique. The self-energy is further matched to QCD through a recently proposed subtraction prescription. The Regge trajectory of the gluon is then defined through renormalization of the reggeized gluon propagator with respect to high energy divergences. Our result is in agreement with previous computations in the literature, providing a non-trivial test of the effective action and the proposed subtraction and renormalization framework.

Chachamis, G; Madrigal, J D; Vera, A Sabio

2013-01-01T23:59:59.000Z

269

Gravity Dual Corrections to the Heavy Quark Potential at Finite-Temperature  

E-Print Network (OSTI)

We apply gauge/gravity duality to compute $1/N^2_c$ corrections to the heavy quark potentials of a quark--anti-quark pair ($Q\\bar Q$) and of a quark--quark pair ($QQ$) immersed into the strongly coupled N = 4 SYM plasma. On the gravity side these corrections come from the exchanges of supergravity modes between two string worldsheets stretching from the UV boundary of AdS space to the black hole horizon in the bulk and smeared over $S^5$. We find that the contributions to the $Q\\bar Q$ potential coming from the exchanges of all of the relevant modes (such as dilaton, massive scalar, 2-form field, and graviton) are all attractive, leading to an attractive net $Q\\bar Q$ potential. We show that at large separations $r$ and/or high-temperature $T$ the potential is of Yukawa-type, dominated by the graviton exchange, in agreement with earlier findings. On the other hand, at small-$r T$ the $Q\\bar Q$ potential scales as $\\sim (1/r) \\ln (1/rT)$. In the case of $QQ$ potential the 2-form contribution changes sign and becomes repulsive: however, the net $QQ$ potential remains attractive. At large-$r T$ it is dominated by the graviton exchange, while at small-$r T$ the $QQ$ potential becomes Coulomb-like.

Hovhannes R. Grigoryan; Yuri V. Kovchegov

2011-05-11T23:59:59.000Z

270

Gluon saturation in dijet production in p-Pb collisions at Large Hadron Collider  

E-Print Network (OSTI)

We study saturation effects in the production of dijets in p-p and p-Pb collisions using the framework of high energy factorization. We focus on central-forward jet configurations, which allow for probing gluon density at low longitudinal momentum fraction. We find significant suppression of the central-forward jet decorrelations in p-Pb compared to p-p, which we attribute to saturation of gluon density in nuclei.

Krzysztof Kutak; Sebastian Sapeta

2012-05-22T23:59:59.000Z

271

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

272

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

273

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

274

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

275

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

276

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

277

Small Quarkonium states in an anisotropic QCD plasma  

E-Print Network (OSTI)

We determine the hard-loop resummed propagator in an anisotropic QCD plasma in general covariant gauges and define a potential between heavy quarks from the Fourier transform of its static limit. We find that the potential exhibits angular dependence and that binding of very small quarkonium states is stronger than in an isotropic plasma.

Yun Guo

2008-05-16T23:59:59.000Z

278

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

279

Quantum chromodynamics and nuclear physics at extreme energy density. Progress report, May 15, 1993--May 14, 1994  

SciTech Connect

This report briefly discusses the following topics: quark-gluon plasma and high-energy collisions; hadron structure and chiral dynamics; nonperturbative studies and nonabelian gauge theories; and studies in quantum field theory.

Mueller, B.; Springer, R.P.

1994-05-15T23:59:59.000Z

280

U.S. Department of Energy Research News  

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

data from the Relativistic Heavy Ion Collider are helping scientists map out the nuclear phase diagram. This research offers insight into the transition of quark-gluon plasma to...

Note: This page contains sample records for the topic "quark gluon plasma" 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

The ALICE Electromagnetic Calorimeter  

Science Conference Proceedings (OSTI)

ALICE (A Large Ion Collider Experiment) is the only LHC experiment at CERN fully dedicated to the study of the quark and gluon plasma. Driven by the RHIC results on jet quenching

S. Gadrat; The ALICE Collaboration

2010-01-01T23:59:59.000Z

282

Geek-Up: K East Reactor Demolition, Retrograde Melting and Cloud...  

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

lead-ions, courtesy the ALICE experiment at CERN Geek-Up11.05.10: Quark Gluon Plasma, Solar-Power Generating Windows and CCS Field Studies Geek-Up: 350,000 Pounds of Paper,...

283

(Nuclear theory). [Research in nuclear physics  

SciTech Connect

This report discusses research in nuclear physics. Topics covered in this paper are: symmetry principles; nuclear astrophysics; nuclear structure; quark-gluon plasma; quantum chromodynamics; symmetry breaking; nuclear deformation; and cold fusion. (LSP)

Haxton, W.

1990-01-01T23:59:59.000Z

284

PowerPoint ?????????  

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

the property of QGP. * Quantitative study of QGP property is underway at RHIC and LHC 2 Quark Gluon Plasma Temperature Baryon Density LHC RHIC Probing QGP with Hard Probes...

285

Recent News from the National Labs | Department of Energy  

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

collision of lead-ions, courtesy the ALICE experiment at CERN Geek-Up11.05.10: Quark Gluon Plasma, Solar-Power Generating Windows and CCS Field Studies Large Hadron...

286

RHIC | Relativistic Heavy Ion Collider  

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

indicate that collisions of small particles with large gold nuclei at the Relativistic Heavy Ion Collider may be serving up miniscule servings of hot quark-gluon plasma. RHIC...

287

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

288

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.

289

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...

290

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

291

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

292

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

293

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

294

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

295

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

296

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

297

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

298

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

299

Phase transition from hadronic matter to quark matter  

Science Conference Proceedings (OSTI)

We study the phase transition from nuclear matter to quark matter within the SU(3) quark mean field model and NJL model. The SU(3) quark mean field model is used to give the equation of state for nuclear matter, while the equation of state for color superconducting quark matter is calculated within the NJL model. It is found that at low temperature, the phase transition from nuclear to color superconducting quark matter will take place when the density is of order 2.5?0 - 5?0. At zero density, the quark phase will appear when the temperature is larger than about 148 MeV. The phase transition from nuclear matter to quark matter is always first order, whereas the transition between color superconducting quark matter and normal quark matter is second order.

P. Wang; A.W. Thomas; A.G. Williams

2007-04-01T23:59:59.000Z

300

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

Note: This page contains sample records for the topic "quark gluon plasma" 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

The Gluon Green's function in N=4 supersymmetric Yang-Mills theory.  

E-Print Network (OSTI)

energy limit of scattering amplitudes in the N = 4 supersymmetric Yang– Mills theory is studied by solving the corresponding BFKL equation in the next– to–leading approximation. The gluon Green’s function is analysed using a newly proposed method suitable... (~ka) ??(~kb) f ( ~ka, ~kb,Y ? ln s s0 ) , (1) where s0 = |~ka||~kb| is the Regge scale. The energy dependence is determined by the universal process–independent gluon Green’s function f . The impact factors, ?,??, depend on the process under study...

Andersen, Jeppe R; Sabio Vera, Agustin

302

Constraining the nuclear gluon distribution in $eA$ processes at RHIC  

E-Print Network (OSTI)

A systematic determination of the gluon distribution is of fundamental interest in understanding the parton structure of nuclei and the QCD dynamics. Currently, the behavior of this distribution at small $x$ (high energy) is completely undefined. In this paper we analyze the possibility of constraining the nuclear effects present in $xg^A$ using the inclusive observables which would be measured in the future electron-nucleus collider at RHIC. We demonstrate that the study of nuclear longitudinal and charm structure functions allows to estimate the magnitude of shadowing and antishadowing effects in the nuclear gluon distribution.

E. R. Cazaroto; F. Carvalho; V. P. Goncalves; F. S. Navarra

2008-04-16T23:59:59.000Z

303

Questions and Answers - What is the charge of an up quark and the charge of  

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

What kinds of quarks are inprotons and neutrons? What kinds of quarks are in<br>protons and neutrons? Previous Question (What kinds of quarks are in protons and neutrons?) Questions and Answers Main Index Next Question (Are quarks confineable for study?) Are quarks confineable for study? What is the charge of an up quark and the charge of a down quark? How many quarks make up a proton and a neutron? Protons and neutrons are each composed of three quarks. Protons are made up of two 'up' quarks and one 'down' quark while neutrons are made up of two 'down' quarks and one 'up' quark. Quarks carry fractional electrical charges. An 'up' quark has a charge of +2/3 and a 'down' quark has a charge of -1/3. Is this consistent with what we know about protons and neutrons? Remember that protons carry an electrical charge of +1 while neutrons carry no electrical charge. We said

304

String Approach to QCD Quarks in Fundamental Representations  

E-Print Network (OSTI)

Straightforward use of AdS/CFT correspondence can give QCD with quarks in adjoint representations. Using an asymmetric orbifold approach we obtain nonsupersymmetric QCD with four quark flavors in fundamental representations of color.

Paul H. Frampton

2004-07-12T23:59:59.000Z

305

Bulk viscosity in nuclear and quark matter: A short review  

E-Print Network (OSTI)

The history and recent progresses in the study of bulk viscosity in nuclear and quark matter are reviewed. The constraints from baryon number conservation and electric neutrality in quark matter on particle densities and fluid velocity divergences are discussed.

Hui Dong; Nan Su; Qun Wang

2007-02-07T23:59:59.000Z

306

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:

307

Cold quark matter, quadratic corrections, and gauge/string duality  

Science Conference Proceedings (OSTI)

We make an estimate of the quadratic correction in the pressure of cold quark matter using gauge/string duality.

Andreev, Oleg [Arnold Sommerfeld Center for Theoretical Physics, LMU-Muenchen, Theresienstrasse 37, 80333 Muenchen (Germany)

2010-04-15T23:59:59.000Z

308

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

309

NCG gluon fusion for the Higgs production at large hadron colliders  

Science Conference Proceedings (OSTI)

A pure NCG gluon fusion contribution to the Higgs production at large hadron colliders is discussed. It is shown that the NCG results become relevant at very high energies. This can be a good signal for the space-time non commutativity events.

Chadou, I.; Mebarki, N.; Bekli, M. R. [Laboratoire de Physique Mathematique et Subatomique, University of Constantine (Algeria)

2012-06-27T23:59:59.000Z

310

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

311

Determination of intrinsic transverse momentum of quarks  

SciTech Connect

It is suggested that the observed universality of the transverse momentum squared distribution for the meson resonances eta, rho, ..omega.., f and K* in soft hadron-hadron interactions arises because they are dominantly produced as a result of quark-antiquark fusion (recombination). The universal value of the slope parameter is then interpreted as due to the intrinsic transverse momentum (k/sub T/) of the quarks which yields the values < k/sub T/ > /sub q/ = 0.36 +- 0.01 GeV/c and < k/sub T//sup 2/ > /sub q/ = 0.16 +- 0.01 (GeV/c)/sup 2/.

Malhotra, P.K.; Orava, R.

1982-11-01T23:59:59.000Z

312

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

313

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

314

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

315

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

316

Memory of Quark Matter Card Game  

E-Print Network (OSTI)

Scientists at the Relativistic Heavy Ion Collider (RHIC, BNL) recently discovered, that the hottest known form of matter is not a gas, but acts like a fluid. Furthermore, this fluid of quarks expands and flows much more perfectly than water or any other well known fluid. This aspect of the RHIC discovery can be introduced even to primary levels of physics education, noting that the usual solid to liquid to gas sequence of phase transitions now are known to be followed by a transition to a nearly perfect fluid, a liquid of quarks, at the largest temperatures made by humans. The educational games described herein were invented by middle school students, members of a Science Club in Hungary. The games were invented for their entertainment, the educational applications in teaching high energy particle and nuclear physics to laypersons are quite unexpected but most welcomed. This manuscript describes games with a deck of cards called Quark Matter cards, where each card represents an elementary particle. The games include an important contribution by Angela Melocoton, an administrator of the Guests, Users and Visitors (GUV) Center at BNL. It describes in simple terms, how to play the Memory of Quark Matter style card games.

J. Csörg?; Cs. Török; T. Csörg?

2013-03-12T23:59:59.000Z

317

Joint resummation for heavy quark production  

E-Print Network (OSTI)

We present joint threshold and recoil resummed transverse momentum distributions for heavy quark hadroproduction, at next-to-leading logarithmic accuracy. We study the dependence of these distributions on the production channel, the color configurations and the differences with the pure threshold-resummed distribution.

Andrea Banfi; Eric Laenen

2004-11-18T23:59:59.000Z

318

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

319

Questions and Answers - Are quarks confineable for study?  

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

is the charge of an up quarkand of down quark? is the charge of an up quark<br>and of down quark? Previous Question (What is the charge of an up quark and of down quark?) Questions and Answers Main Index Next Question (Is vacuum matter? What are ten things that are not matter? ) Is vacuum matter? What are tenthings that are not matter? Are quarks confineable for study? Quarks we study at Jefferson Lab are confined to each other by nature's laws. We shine our electrons on them to observe their behavior in their confined state. This is not so different from turning on a light to see a gold fish swimming in a glass bowl. Author: Nathan Isgur, Theory Group Leader (Other answers by Nathan Isgur) Related Pages: All About Atoms What is the smallest particle of matter known? Could there be anything smaller inside of an electron or inside of a

320

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

Note: This page contains sample records for the topic "quark gluon plasma" 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

The uncertainties due to quark energy loss on determining nuclear sea quark distribution from nuclear Drell-Yan data  

E-Print Network (OSTI)

By means of two different parametrizations of quark energy loss and the nuclear parton distributions determined only with lepton-nuclear deep inelastic scattering experimental data, a leading order phenomenological analysis is performed on the nuclear Drell-Yan differential cross section ratios as a function of the quark momentum fraction in the beam proton and target nuclei for E772 experimental data. It is shown that there is the quark energy loss effect in nuclear Drell-Yan process apart from the nuclear effects on the parton distribution as in deep inelastic scattering. The uncertainties due to quark energy loss effect is quantified on determining nuclear sea quark distribution by using nuclear Drell-Yan data. It is found that the quark energy loss effect on nuclear Drell-Yan cross section ratios make greater with the increase of quark momentum fraction in the target nuclei. The uncertainties from quark energy loss become bigger as the nucleus A come to be heavier. The Drell-Yan data on proton incident middle and heavy nuclei versus deuterium would result in an overestimate for nuclear modifications on sea quark distribution functions with neglecting the quark energy loss. Our results are hoped to provide good directional information on the magnitude and form of nuclear modifications on sea quark distribution functions by means of the nuclear Drell-Yan experimental data.

C. G. Duan; N. Liu; G. L. Li

2008-11-05T23:59:59.000Z

322

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

323

RHIC | Why Does Quark Matter Matter?  

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

Why Does Quark Matter 'Matter'? Why Does Quark Matter 'Matter'? The history of modern technological development can be viewed as a series of investigations, with ever increasing resolution, into the microscopic structure of matter. Since the days of the early Greek philosophers, science has been on a continual quest to find the smallest piece - the most fundamental building block - forming the substance of the universe. STAR researchers During that journey, many beautiful and exotic properties of the subatomic world have been discovered: particles with wave-like properties the ultimate position of which can never be known; "particles" of light that deliver a fixed amount of energy when they strike the atoms of a material's surface; particles in some types of electrical conductors that

324

Heavy Quarks, QCD, and Effective Field Theory  

SciTech Connect

The research supported by this OJI award is in the area of heavy quark and quarkonium production, especially the application Soft-Collinear E#11;ective Theory (SCET) to the hadronic production of quarkonia. SCET is an e#11;ffective theory which allows one to derive factorization theorems and perform all order resummations for QCD processes. Factorization theorems allow one to separate the various scales entering a QCD process, and in particular, separate perturbative scales from nonperturbative scales. The perturbative physics can then be calculated using QCD perturbation theory. Universal functions with precise fi#12;eld theoretic de#12;nitions describe the nonperturbative physics. In addition, higher order perturbative QCD corrections that are enhanced by large logarithms can be resummed using the renormalization group equations of SCET. The applies SCET to the physics of heavy quarks, heavy quarkonium, and similar particles.

Thomas Mehen

2012-10-09T23:59:59.000Z

325

Dual quark condensate and dressed Polyakov loops  

E-Print Network (OSTI)

We construct a new order parameter for finite temperature QCD by considering the quark condensate for U(1)-valued temporal boundary conditions for the fermions. Fourier transformation with respect to the boundary condition defines the dual condensate. This quantity corresponds to an equivalence class of Polyakov loops, thereby being an order parameter for the center symmetry. We explore the duality relation between the quark condensate and these dressed Polyakov loops numerically, using quenched lattice QCD configurations below and above the QCD phase transition. It is demonstrated that the Dirac spectrum responds differently to changing the boundary condition, in a manner that reproduces the expected Polyakov loop pattern. We find the dressed Polyakov loops to be dominated by the lowest Dirac modes, in contrast to thin Polyakov loops investigated earlier.

Erek Bilgici; Falk Bruckmann; Christof Gattringer; Christian Hagen

2008-01-28T23:59:59.000Z

326

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

327

Magnetic Phases in Dense Quark Matter  

E-Print Network (OSTI)

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

Vivian de la Incera

2007-08-12T23:59:59.000Z

328

Magnetic Phases in Dense Quark Matter  

SciTech Connect

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

Incera, Vivian de la [Department of Physics, Western Illinois University, Macomb, IL 61455 (United States)

2007-10-26T23:59:59.000Z

329

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

330

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

331

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

332

PLASMA GENERATOR  

DOE Patents (OSTI)

This patent describes apparatus for producing an electricity neutral ionized gas discharge, termed a plasma, substantially free from contamination with neutral gas particles. The plasma generator of the present invention comprises a plasma chamber wherein gas introduced into the chamber is ionized by a radiofrequency source. A magnetic field is used to focus the plasma in line with an exit. This magnetic field cooperates with a differential pressure created across the exit to draw a uniform and uncontaminated plasma from the plasma chamber.

Foster, J.S. Jr.

1958-03-11T23:59:59.000Z

333

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

334

Domain growth and ordering kinetics in dense quark matter  

Science Conference Proceedings (OSTI)

The kinetics of chiral transitions in quark matter is studied in a two-flavor Nambu-Jona-Lasinio model. We focus on the phase-ordering dynamics subsequent to a temperature quench from the massless quark phase to the massive quark phase. We study the dynamics by considering a phenomenological model (Ginzburg-Landau free-energy functional). The morphology of the ordering system is characterized by the scaling of the order-parameter correlation function.

Singh, A.; Puri, S. [Jawaharlal Nehru University, School of Physical Sciences (India); Mishra, H., E-mail: hm@prl.res.in [Physical Research Laboratory, Theory Division (India)

2012-06-15T23:59:59.000Z

335

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

336

Thermodynamics of QCD at large quark chemical potential  

E-Print Network (OSTI)

We review the existing weak-coupling results on the thermodynamic potential of deconfined QCD at small and large quark chemical potential and compare with results from lattice gauge theory as well as the exactly solvable case of large-N_f QCD. We also discuss the new analytical results on non-Fermi-liquid effects in entropy and specific heat as well as in dispersion laws of quark quasiparticles at large quark chemical potential.

Andreas Gerhold; Andreas Ipp; Anton Rebhan

2005-12-21T23:59:59.000Z

337

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

338

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

339

Parton Equilibration Enforcing Baryon Number Conservation  

E-Print Network (OSTI)

Parton equilibration for a thermally equilibrated but chemically non-equilibrated quark gluon plasma is presented. Parton equilibration is studied enforcing baryon numbver conservation. Process like quark flavour interchanging is also considered. The degree of equilibration is studied comparatively for the various reactions / constraints that are being considered.

Abhijit Sen

2007-10-01T23:59:59.000Z

340

Electric and Magnetic Screening Masses at Finite Temperature from Generalized Polyakov-Line Correlations in Two-flavor Lattice QCD  

E-Print Network (OSTI)

Screenings of the quark-gluon plasma in electric and magnetic sectors are studied on the basis of generalized Polyakov-line correlation functions in lattice QCD simulations with two flavors of improved Wilson quarks. Using the Euclidean-time reflection ($\\R$) and the charge conjugation ($\\Ca$), electric and magnetic screening masses are extracted in a gauge invariant manner. Long distance behavior of the standard Polyakov-line correlation in the quark-gluon plasma is found to be dictated by the magnetic screening. Also, ratio of the two screening masses agrees with that obtained from the dimensionally-reduced effective field theory and the ${\\cal N}=4$ supersymmetric Yang-Mills theory.

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

2010-03-06T23:59:59.000Z

Note: This page contains sample records for the topic "quark gluon plasma" 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

Phase diagram of hot quark matter under magnetic field  

Science Conference Proceedings (OSTI)

I review the computation of the phase diagram of hot quark matter in strong magnetic field, at zero baryon density, within an effective model of Quantum Chromodynamics.

Ruggieri, Marco [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)

2010-12-22T23:59:59.000Z

342

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 ...

343

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

344

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

345

Proposal to support junior scientists participation of Quark Matter 2004  

SciTech Connect

This report summarizes the student and post-doc support budget for quark matter 2004 conference, held at Oakland in January 2004.

Huan Zhong Huang; Kenneth Barish; Hans Georg Ritter

2005-12-15T23:59:59.000Z

346

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

347

Color superconductivity in ultra-dense quark matter  

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. This phenomenon is called color superconductivity. In these proceedings I review the underlying physics of color superconductivity and our current understanding of the possible phases of real-world quark matter. Then I consider how lattice gauge theorists would proceed to investigate the phase structure of dense quark matter if it were possible to perform the path integral numerically, i.e. if the sign problem had been solved.

Mark G. Alford

2006-10-06T23:59:59.000Z

348

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

349

Jefferson Lab Science Series - Hidden Worlds - Hunting for Quarks...  

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

Extinctions and Giant Asteroids) Science Series Video Archive Next Video (Comic Book Physics) Comic Book Physics Hidden Worlds - Hunting for Quarks in Ordinary Matter Dr....

350

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

351

THERMODYNAMICS AND HEAVY-QUARK FREE ENERGIES AT FINITE TEMPERATURE AND DENSITY WITH TWO FLAVORS OF IMPROVED WILSON QUARKS.  

SciTech Connect

Thermodynamics of two-flavor QCD at finite temperature and density is studied on a 16{sup 3} x 4 lattice, using a renormalization group improved gauge action and the clover improved Wilson quark action. In the simulations along lines of constant m{sub PS}/m{sub V}, we calculate the Taylor expansion coefficients of the heavy-quark free energy with respect to the quark chemical potential ({mu}{sub q}) up to the second order. By comparing the expansion coefficients of the free energies between quark(Q) and antiquark({anti Q}), and between Q and Q, we find a characteristic difference at finite {mu}{sub q} due to the first order coefficient of the Taylor expansion. We also calculate the quark number and isospin susceptibilities, and find that the second order coefficient of the quark number susceptibility shows enhancement around the pseudo-critical temperature.

MAEZAWA,Y.; HATSUDA, T.; AOKI, S.; KANAYA, K.; EJIRI, S.; ISHII, N.; UKITA, N.; UMEDA, T.

2007-07-30T23:59:59.000Z

352

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

353

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

354

Strange quark content of the nucleon  

E-Print Network (OSTI)

We discuss the calculation of disconnected diagrams needed for determining the strange quark content of the nucleon on the lattice. We present results for the strange scalar form factor and the related parameter fT s, which enters into the cross-section for the scattering of dark matter off nuclei in supersymmetric extensions of the standard model. In addition, we present results for the strange contribution to the nucleon’s axial and electromagnetic form factors. The calculations were performed with two dynamical flavors of Wilson fermions on a 24 3 × 64 anisotropic lattice with as ? 3at ? 0.11 fm and M? ? 400 MeV.

James Osborn; Claudio Rebbi Ab; Ronald Babich

2008-01-01T23:59:59.000Z

355

ASSOCIATED HIGGS BOSON PRODUCTION WITH HEAVY QUARKS.  

SciTech Connect

The production of a Higgs boson in association with a pair of e quarks will play a very important role at both hadron and lepton colliders. We review the status of theoretical predictions and their relevance to Higgs boson studies, with particular emphasis on the recently calculated NLO QCD corrections to the inclusive cross section for p{bar p}, pp {yields} t{bar t}h. We conclude by briefly discussing the case of exclusive b{bar b}h production and the potential of this process in revealing signals of new physics beyond the Standard Model.

DAWSON,S.ORR,L.H.REINA,L.WACKEROTH,D.

2003-03-15T23:59:59.000Z

356

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

357

Soft-gluon resummation for Higgs differential distributions at the Large Hadron Collider  

E-Print Network (OSTI)

We study the transverse-momentum (q_T) and rapidity (y) distributions of the Higgs boson in perturbative QCD, including the most advanced theoretical information presently available: fixed-order perturbation theory at Next-to-Leading Order (NLO) in the large-q_T region (q_T ~ M_H, being M_H the Higgs mass), and soft-gluon resummation at the Next-to-Next-to-Leading Logarithmic accuracy (NNLL) in the small-q_T region (q_T Large Hadron Collider (LHC).

Giuseppe Bozzi

2007-10-12T23:59:59.000Z

358

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

359

Searches for New Vector Like Quarks: Higgs Channels  

E-Print Network (OSTI)

New vector-like quarks can mix sizably with first generation Standard Model quarks without conflicting with current experimental constraints. Searches for such new quarks have been performed in pair production and electroweak single production channels with subsequent decays into electroweak gauge bosons. To fully explore the underlying structure of the theory the channels with heavy quark decays into Higgs bosons are crucial and in this article we consider for the first time the LHC reach for such channels. The two main production mechanisms involve single production of new quarks through the fusion of a vector boson and the Higgs and single production in association with a Higgs boson. We show that both channels have promising reach at the LHC and that they complement the current direct searches involving decays into electroweak gauge bosons.

Anupama Atre; Mikael Chala; Jose Santiago

2013-02-01T23:59:59.000Z

360

Searches for New Vector Like Quarks: Higgs Channels  

E-Print Network (OSTI)

New vector-like quarks can mix sizably with first generation Standard Model quarks without conflicting with current experimental constraints. Searches for such new quarks have been performed in pair production and electroweak single production channels with subsequent decays into electroweak gauge bosons. To fully explore the underlying structure of the theory the channels with heavy quark decays into Higgs bosons are crucial and in this article we consider for the first time the LHC reach for such channels. The two main production mechanisms involve single production of new quarks through the fusion of a vector boson and the Higgs and single production in association with a Higgs boson. We show that both channels have promising reach at the LHC and that they complement the current direct searches involving decays into electroweak gauge bosons.

Atre, Anupama; Santiago, Jose

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "quark gluon plasma" 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

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

362

The uncertainties due to quark energy loss on determining nuclear sea quark distribution from nuclear Drell-Yan data  

E-Print Network (OSTI)

By means of two different parametrizations of quark energy loss and the nuclear parton distributions determined only with lepton-nuclear deep inelastic scattering experimental data, a leading order phenomenological analysis is performed on the nuclear Drell-Yan differential cross section ratios as a function of the quark momentum fraction in the beam proton and target nuclei for E772 experimental data. It is shown that there is the quark energy loss effect in nuclear Drell-Yan process apart from the nuclear effects on the parton distribution as in deep inelastic scattering. The uncertainties due to quark energy loss effect is quantified on determining nuclear sea quark distribution by using nuclear Drell-Yan data. It is found that the quark energy loss effect on nuclear Drell-Yan cross section ratios make greater with the increase of quark momentum fraction in the target nuclei. The uncertainties from quark energy loss become bigger as the nucleus A come to be heavier. The Drell-Yan data on proton incident mi...

Duan, C G; Li, G L

2008-01-01T23:59:59.000Z

363

The influence of quark energy loss on extracting nuclear sea quark distribution from nuclear Drell-Yan experimental data  

E-Print Network (OSTI)

By means of two typical kinds of quark energy loss parametrization and the nuclear parton distributions determined only with lepton-nuclear deep inelastic scattering experimental data, a leading order analysis are performed on the proton-induced Drell-Yan differential cross section ratios of tungsten versus deuterium as a function of the quark momentum fraction in the beam proton and target nuclei. It is found that the theoretical results with quark energy loss are in good agreement with the experimental data. The quark energy loss effect produce approximately 3% to 11% suppression on the Drell-Yan differential cross section ratios $R_{W/D}$ in the range $0.05\\leq x_2\\leq0.3$. The application of nuclear Drell-Yan data with heavy targets is remarkably subject to difficulty in the constraints of the nuclear sea-quark distribution.

Chun-Gui, Duan

2008-01-01T23:59:59.000Z

364

The influence of quark energy loss on extracting nuclear sea quark distribution from nuclear Drell-Yan experimental data  

E-Print Network (OSTI)

By means of two typical kinds of quark energy loss parametrization and the nuclear parton distributions determined only with lepton-nuclear deep inelastic scattering experimental data, a leading order analysis are performed on the proton-induced Drell-Yan differential cross section ratios of tungsten versus deuterium as a function of the quark momentum fraction in the beam proton and target nuclei. It is found that the theoretical results with quark energy loss are in good agreement with the experimental data. The quark energy loss effect produce approximately 3% to 11% suppression on the Drell-Yan differential cross section ratios $R_{W/D}$ in the range $0.05\\leq x_2\\leq0.3$. The application of nuclear Drell-Yan data with heavy targets is remarkably subject to difficulty in the constraints of the nuclear sea-quark distribution.

Duan Chun-Gui; Liu Na

2008-09-28T23:59:59.000Z

365

Evidence for nuclear gluon shadowing from the ALICE measurements of PbPb ultraperipheral exclusive J/{\\psi} production  

E-Print Network (OSTI)

We show that the recent ALICE measurements of exclusive J/{\\psi} production in ultraperipheral PbPb collisions at 2.76 TeV provide the first direct experimental evidence for the strong nuclear gluon shadowing in lead at $x \\sim 10^{-3}$. The evidence is based on the comparison of the nuclear suppression factor S(x\\approx 0.001)=0.61^{+0.05}_{-0.04} found in the analysis of the coherent J/{\\psi} photoproduction cross sections measured by ALICE with the nuclear gluon shadowing predicted by the global fits of nuclear parton distributions and by the leading twist theory of nuclear shadowing.

Guzey, V; Strikman, M; Zhalov, M

2013-01-01T23:59:59.000Z

366

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

367

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

368

Weinberg Angle and Integer Electric Charges of Quarks  

E-Print Network (OSTI)

Orthogonality between photon and Z boson involves the Weinberg angle and a scheme for assignments of electric charge and weak isospin to leptons and quarks coupling to photon and Z. The Han-Nambu scheme, with integer electric charges for quarks, satisfies photon-Z orthogonality with sin^2(theta_W)= 0.25 in leading order. Experimental results for photon-photon fusion into charm-anticharm and bottom-antibottom pairs provide further support for assigning integer electric charges to quarks.

Martin A. Faessler

2013-08-22T23:59:59.000Z

369

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

370

Combining Quark and Link Smearing to Improve Extended Baryon Operators  

SciTech Connect

The effects of Gaussian quark-field smearing and analytic stout-link smearing on the correlations of gauge-invariant extended baryon operators are studied. Gaussian quark-field smearing substantially reduces contributions from the short wavelength modes of the theory, while stout-link smearing significantly reduces the noise from the stochastic evaluations. The use of gauge-link smearing is shown to be crucial for baryon operators constructed of covariantly-displaced quark fields. Preferred smearing parameters are determined for a lattice spacing a_s ~ 0.1 fm.

Adam Lichtl; Subhasish Basak; Robert Edwards; George T. Fleming; Urs M. Heller; Colin Morningstar; David Richards; Ikuro Sato; Stephen Wallace

2005-09-29T23:59:59.000Z

371

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

372

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

373

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

374

The Particle Adventure | What is the world made of? | The naming of quarks  

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

The naming of quarks The naming of quarks The naming of quarks The naming of quarks... ...began when, in 1964, Murray Gell-Mann and George Zweig suggested that hundreds of the particles known at the time could be explained as combinations of just three fundamental particles. Gell-Mann chose the name "quarks," pronounced "kworks," for these three particles, a nonsense word used by James Joyce in the novel Finnegan's Wake: "Three quarks for Muster Mark!" In order to make their calculations work, the quarks had to be assigned fractional electrical charges of 2/3 and -1/3. Such charges had never been observed before. Quarks are never observed by themselves, and so initially these quarks were regarded as mathematical fiction. Experiments have since convinced physicists that not only do quarks exist, but there are six of them, not three.

375

Reading Comprehension - Looking for Quarks Inside the Atom  

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

Looking for Quarks Inside the Atom Looking for Quarks Inside the Atom In the late 1960's, three scientists ran some accelerator experiments to study the nucleus at the _________ outside edge center perimeter of the atom. They ran the experiments because they wanted to know more about the structure of the _________ nucleus accelerator electromagnet spectrometer . They found that the protons and neutrons in the nucleus are made of quarks. The discovery of _________ alpha quarks nuclei electron raised new questions about the nucleus. The three scientists are Richard Taylor, Henry Kendall and Jerome Friedman. They did their experiments from 1967 to 1973 in California at the Stanford Linear Accelerator Center, called SLAC for short. These scientists won the 1990 Nobel Prize in Physics, one of the world's greatest honors for

376

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

377

On thermal nucleation of quark matter in compact stars  

E-Print Network (OSTI)

The possibility of a hadron-quark phase transition in extreme astrophysical phenomena such as the collapse of a supernova is not discarded by the modern knowledge of the high-energy nuclear and quark-matter equations of state. Both the density and the temperature attainable in such extreme processes are possibly high enough to trigger a chiral phase transition. However, the time scales involved are an important issue. Even if the physical conditions for the phase transition are favorable (for a system in equilibrium), there may not be enough time for the dynamical process of phase conversion to be completed. We analyze the relevant time scales for the phase conversion via thermal nucleation of bubbles of quark matter and compare them to the typical astrophysical time scale, in order to verify the feasibility of the scenario of hadron-quark phase conversion during, for example, the core-collapse of a supernova.

Mintz, B W; Schaffner-Bielich, J; Pagliara, G

2010-01-01T23:59:59.000Z

378

Search for Higgs bosons produced in association with b quarks  

E-Print Network (OSTI)

We present a search for neutral Higgs bosons ? decaying into bb? , produced in association with b quarks in pp? collisions. This process could be observable in supersymmetric models with high values of tan??. The event ...

Bauer, Gerry P.

379

Hadron resonances with a quark core embedded in the continuum  

SciTech Connect

We investigate the excited baryons and mesons which cannot be described in terms of a simple constituent quark model, such as {Lambda}(1405) and X(3872) as a resonance in a coupled channel hadron-hadron (baryon-meson or meson-meson) scattering with a 'bound state embedded in the continuum' (BSEC). For this purpose, we solve the Lippmann-Schwinger equation including a BSEC in the momentum space. This BSEC is introduced by hand, as a state not originated from a simple baryon-meson or meson-meson system. We assume it comes from the three-quark state or quark-anti quark state and show such a picture can describe the {Lambda}(1405) and X(3872) resonances.

Shimizu, Kiyotaka [Department of Physics, Sophia University, Chiyoda-ku, Tokyo 102-8554 (Japan); Takeuchi, Sachiko [Japan College of Social Work, Kiyose, Tokyo 204-8555 (Japan); Takizawa, Makoto [Showa Pharmaceutical University, Machida, Tokyo 194-8543 (Japan)

2011-05-06T23:59:59.000Z

380

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

Note: This page contains sample records for the topic "quark gluon plasma" 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

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 reponse function in this y-scaling region is, within the traditional frame work sensitive to the nucleon momentum distribution at large momentum. We find a surprizingly 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.

1988-11-20T23:59:59.000Z

382

Thermal conductivity of dense quark matter and cooling of stars  

E-Print Network (OSTI)

The thermal conductivity of the color-flavor locked phase of dense quark matter is calculated. The dominant contribution to the conductivity comes from photons and Nambu-Goldstone bosons associated with breaking of baryon number which are trapped in the quark core. Because of their very large mean free path the conductivity is also very large. The cooling of the quark core arises mostly from the heat flux across the surface of direct contact with the nuclear matter. As the thermal conductivity of the neighboring layer is also high, the whole interior of the star should be nearly isothermal. Our results imply that the cooling time of compact stars with color-flavor locked quark cores is similar to that of ordinary neutron stars.

Igor A. Shovkovy; Paul J. Ellis

2002-04-11T23:59:59.000Z

383

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

384

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

385

Helicity Probabilities For Heavy Quark Fragmentation Into Excited Mesons  

E-Print Network (OSTI)

In the fragmentation of a heavy quark into a heavy meson whose light degrees of freedom have angular momentum $3/2$, all the helicity probabilities are completely determined in the heavy quark limit up to a single probability $w_{3/2}$. We point out that this probability depends on the longitudinal momentum fraction $z$ of the meson and on its transverse momentum $p_\\bot$ relative to the jet axis. We calculate $w_{3/2}$ as a function of scaling variables corresponding to $z$ and $p_\\bot$ for the heavy quark limit of the perturbative QCD fragmentation functions for $b$ quark to fragment into $(b \\bar c)$ mesons. In this model, the light degrees of freedom prefer to have their angular momentum aligned transverse to, rather than along, the jet axis. Implications for the production of excited heavy mesons, like $D^{**}$ and $B^{**}$, are discussed.

Tzu Chiang Yuan

1994-07-20T23:59:59.000Z

386

QuarkNet - Educational Materials from 2013 Workshop  

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

Makers QuarkNet and the Fermi Mars Rover System (Brian Nord FNAL ) - PowerPoint Underwater Robotics - Mark Rowzee, Naperville North - PowerPoint Version Dark Energy Resources...

387

Unlike particle correlations and the strange quark matter distillation process  

E-Print Network (OSTI)

We present a new technique for observing the strange quark matter distillation process based on unlike particle correlations. A simulation is presented based on the scenario of a two-phase thermodynamical evolution model.

D. Ardouin; Sven Soff; C. Spieles; S. A. Bass; H. Stocker; D. Gourio; S. Schramm; C. Greiner; R. Lednicky; V. L. Lyuboshits; J. P. Coffin; C. Kuhn

2002-03-14T23:59:59.000Z

388

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

389

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

390

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

391

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

392

Free Energy and Plaquette expectation value for gluons on the lattice, in three dimensions  

E-Print Network (OSTI)

We calculate the perturbative value of the Free Energy in Lattice QCD in three dimensions, up to three loops. Our calculation is performed using the Wilson formulation for gluons in SU(N) gauge theories. The Free Energy is directly related to the average plaquette. To carry out the calculation, we compute the coefficients involved in the perturbative expansion of the Free Energy up to three loops, using an automated set of procedures developed by us in Mathematica. The dependence on N is shown explicitly in our results. For purposes of comparison, we also present the individual contributions from every diagram. These have been obtained by means of two independent calculations, in order to cross check our results.

H. Panagopoulos; A. Skouroupathis; A. Tsapalis

2006-01-06T23:59:59.000Z

393

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

394

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

395

16. Heavy-Quark and Soft-Collinear Effective Theory 1 16. Heavy-Quark and Soft-Collinear Effective Theory  

E-Print Network (OSTI)

16. Heavy-Quark and Soft-Collinear Effective Theory 1 16. Heavy-Quark and Soft-Collinear Effective the quantum fluctuations of such heavy particles are "integrated out" from the generating functional integral.lbl.gov) February 16, 2012 14:07 #12;2 16. Heavy-Quark and Soft-Collinear Effective Theory 16.2. Heavy

396

QuarkNet Workshop: Beyond Human Error  

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

Human Error Human Error QuarkNet Workshop for High School Science Teachers 8:30 am to 4:00 pm, August 1 -3, 2012 at Fermi National Accelerator Laboratory This was a three-day workshop for high school science teachers. Measurement and error are key ingredients for all science applications. Both align with the Next Generation Science Standards, but many high school students struggle to understand the importance of error analysis and prevention. Over the three days we examined multiple experiments going on at Fermilab and discussed the ways that scientists take measurements and reduce error on these projects. Participants met and worked with scientists from Fermilab and University of Chicago to look at how error analysis takes place at Fermilab and bridged those ideas into high school classes. Teachers discussed lesson plans available at Fermilab and their own methods of teaching error analysis. Additionally, participants heard from high school students who participated in summer research as they presented their findings and linked students' learning back to the teachers' understanding of error recognition and analysis.

397

The radiance of the gluon spin : constraining the proton spin structure with the direct photon double helicity asymmetry  

E-Print Network (OSTI)

Although fundamental to the observable universe, the proton is not elementary. Rather the particle is a bound state of three valence quarks and the QCD vacuum that condenses around them, its properties an amalgamation of ...

Betancourt, Michael (Michael Joseph)

2012-01-01T23:59:59.000Z

398

Plasma valve  

DOE Patents (OSTI)

A plasma valve includes a confinement channel and primary anode and cathode disposed therein. An ignition cathode is disposed adjacent the primary cathode. Power supplies are joined to the cathodes and anode for rapidly igniting and maintaining a plasma in the channel for preventing leakage of atmospheric pressure through the channel.

Hershcovitch, Ady (Mount Sinai, NY); Sharma, Sushil (Hinsdale, IL); Noonan, John (Naperville, IL); Rotela, Elbio (Clarendon Hills, IL); Khounsary, Ali (Hinsdale, IL)

2003-01-01T23:59:59.000Z

399

PLASMA ENERGIZATION  

DOE Patents (OSTI)

BS>A method is given for ion cyclotron resonance heatthg of a magnetically confined plasma by an applied radio-frequency field. In accordance with the invention, the radiofrequency energy is transferred to the plasma without the usual attendent self-shielding effect of plasma polarlzatlon, whereby the energy transfer is accomplished with superior efficiency. More explicitly, the invention includes means for applying a radio-frequency electric field radially to an end of a plasma column confined in a magnetic mirror field configuration. The radio-frequency field propagates hydromagnetic waves axially through the column with the waves diminishing in an intermediate region of the column at ion cyclotron resonance with the fleld frequency. In such region the wave energy is converted by viscous damping to rotational energy of the plasma ions. (AEC)

Furth, H.P.; Chambers, E.S.

1962-03-01T23:59:59.000Z

400

PLASMA DEVICE  

DOE Patents (OSTI)

A device is described for establishing and maintaining a high-energy, rotational plasma for use as a fast discharge capacitor. A disc-shaped, current- conducting plasma is formed in an axinl magnetic field and a crossed electric field, thereby creating rotational kinetic enengy in the plasma. Such energy stored in the rotation of the plasma disc is substantial and is convertible tc electrical energy by generator action in an output line electrically coupled to the plasma volume. Means are then provided for discharging the electrical energy into an external circuit coupled to the output line to produce a very large pulse having an extremely rapid rise time in the waveform thereof. (AE C)

Baker, W.R.

1961-08-22T23:59:59.000Z

Note: This page contains sample records for the topic "quark gluon plasma" 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

Chemical and kinetic equilibrations via radiative parton transport  

E-Print Network (OSTI)

A hot and dense partonic system can be produced in the early stage of a relativistic heavy ion collision. How it equilibrates is important for the extraction of Quark-Gluon Plasma properties. We study the chemical and kinetic equilibrations of the Quark-Gluon Plasma using a radiative transport model. Thermal and Color-Glass-Condensate motivated initial conditions are used. We observe that screened parton interactions always lead to partial pressure isotropization. Different initial pressure anisotropies result in the same asymptotic evolution. Comparison of evolutions with and without radiative processes shows that chemical equilibration interacts with kinetic equilibration and radiative processes can contribute significantly to pressure isotropization.

Bin Zhang; Warner A. Wortman

2011-02-21T23:59:59.000Z

402

Viscosity, wave damping and shock wave formation in cold hadronic matter  

E-Print Network (OSTI)

We study linear and nonlinear wave propagation in a dense and cold hadron gas and also in a cold quark gluon plasma, taking viscosity into account and using the Navier-Stokes equation. The equation of state of the hadronic phase is derived from the nonlinear Walecka model in the mean field approximation. The quark gluon plasma phase is described by the MIT equation of state. We show that in a hadron gas viscosity strongly damps wave propagation and also hinders shock wave formation. This marked difference between the two phases may have phenomenological consequences and lead to new QGP signatures.

D. A. Fogaça; F. S. Navarra; L. G. Ferreira Filho

2013-05-03T23:59:59.000Z

403

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

404

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

405

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

406

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

407

Analytic derivation of dual gluons and monopoles from SU(2) lattice Yang-Mills theory. III. Plaquette representation  

E-Print Network (OSTI)

In this series of three papers, we generalize the derivation of dual photons and monopoles by Polyakov, and Banks, Myerson and Kogut, to obtain approximative models of SU(2) lattice gauge theory. Our approach is based on stationary phase approximations. In this third article, we start from the plaquette representation of 3-dimensional SU(2) lattice gauge theory. By extending a work of Borisenko, Voloshin and Faber, we transform the expectation value of a Wilson loop into a path integral over a dual gluon field and monopole variables. The action contains the tree-level Coulomb interaction and a nonlinear coupling between dual gluons, monopoles and current. We show that this model exhibits confinement if a condition on the monopole self-energy is satisfied.

Florian Conrady

2006-10-23T23:59:59.000Z

408

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

409

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

410

Quark Stars as inner engines for Gamma Ray Bursts?  

E-Print Network (OSTI)

A model for Gamma ray bursts inner engine based on quark stars (speculated to exist in nature) is presented. We describe how and why these objects might constitute new candidates for GRB inner engines. At the heart of the model is the onset of exotic phases of quark matter at the surface of such stars, in particular the 2-flavor color superconductivity. A novel feature of such a phase is the generation of particles which are unstable to photon decay providing a natural mechanism for a fireball generation; an approach which is fundamentally different from models where the fireball is generated during collapse or conversion of neutron star to quark star processes. The model is capable of reproducing crucial features of Gamma ray bursts, such as the episodic activity of the engine (multiple and random shell emission) and the two distinct categories of the bursts (two regimes are isolated in the model with \\sim 2 s and \\sim 81 s burst total duration).

R. Ouyed; F. Sannino

2001-03-01T23:59:59.000Z

411

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

412

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

413

A COMPREHENSIVE NEW DETECTOR FOR DETAILED STUDY OF THE QGP, INITIAL CONDITION AND SPIN PHYSICS AT RHIC II.  

SciTech Connect

A case is presented for compelling physics at a high luminosity RHIC II collider. A comprehensive new detector system is introduced to address this physics. The experimental focus is on detailed jet tomography of the quark gluon plasma (QGP); measuring gluon saturation in the nucleus, investigating the color glass condensate, measuring effects of the QCD vacuum on particle masses, determining the structure and dynamics within the proton and possible new phenomena. The physics and detector capabilities are introduced.

HARRIS, J.W.; BELLWIED, R.; SMIRNOV, N.; STEINBERG, P.; SURROW, B.; ULLRICH, T.

2004-03-15T23:59:59.000Z

414

Plasma Nitrocarburizing  

Science Conference Proceedings (OSTI)

...heat pollution Reduced processing times Reduced energy consumption Reduced treatment gas consumption Industrial plasma nitrocarburizing processing modules contain: Vacuum furnace Vacuum system Gas supply with gas mixing and pressure control system Electric power supply unit Microprocessor control unit...

415

HEAVY BARYONS: A COMBINED LARGE Nc AND HEAVY QUARK EXPANSION FOR ELECTROWEAK CURRENTS  

E-Print Network (OSTI)

The combined large Nc and heavy quark limit for baryons containing a single heavy quark is discussed. The combined large Nc and heavy quark expansion of the heavy quark bilinear operators is obtained. In the combined expansion the corrections proportional to mN/mQ are summed to all orders. In particular, the combined expansion can be used to determine semileptonic form factors of heavy baryons in the combined limit. 1

Boris A. Gelman

2002-01-01T23:59:59.000Z

416

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

417

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

418

Next-to-next-to-leading order soft gluon corrections in direct photon production.  

E-Print Network (OSTI)

) , (2.4) where µF is the factorization scale, CA = Nc, and ?0 = (11CA ? 2nf )/3, with nf the number of quark flavors. We also define for use below T qq¯2 = ?(?0/4) + 2CF ln(p2T/s) and T qg 2 = ?(3/4)CF + (CF + CA) ln(p2T/s). Finally we write c fifj 1 = c... µ fifj 1 + T fifj 1 . For qq¯ ? ?g we have cµ qq¯1 = CF [ ?3 2 ? ln ( p2T s )] ln ( µ2F s ) + ?0 4 ln ( µ2R s ) , (2.5) and T qq¯1 = CF [3/2+ln(p2T/s)] ln(p 2 T/s)?(?0/4) ln(µ2R/s)+c? qq¯ 1 where c ?qq¯ 1 is defined in Eq. (3.11) of Ref. [5]. For qg...

Kidonakis, Nikolaos; Owens, J F

419

Ferromagnetism and Superconductivity in Quark Matter - Color magnetic superconductivity -  

E-Print Network (OSTI)

A coexistent phase of spin polarization and color superconductivity in high-density QCD is studied at zero temperature. The axial-vector self-energy stemming from the Fock exchange term of the one-gluon-exchange interaction has a central role to cause spin polarization. As a significant feature, the Fermi surface is deformed by the axial-vector self-energy and then rotation symmetry is spontaneously broken down. The gap function results in being anisotropic in the momentum space in accordance with the deformation. It is found that spin polarization barely conflicts with color superconductivity, and almost coexists with it.

Toshitaka Tatsumi; Tomoyuki Maruyama; Eiji Nakano

2003-12-25T23:59:59.000Z

420

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

Note: This page contains sample records for the topic "quark gluon plasma" 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.


421

J/Psi Production by Charm Quark Coalescence  

E-Print Network (OSTI)

Production of $c\\bar c$ pairs in elementary hadron-hadron collisions is introduced in a simulation of relativistic heavy ion collisions. Coalescence of charmed quarks and antiquarks into various charmonium states is performed and the results are compared to PHENIX J$/\\psi$ Au+Au data. The $\\chi$ and $\\psi$' bound states must be included as well as the ground state J$/\\psi$, given the appreciable feeding from the excited states down to the J$/\\psi$ via gamma decays. Charmonium coalescence is found to take place at relatively late times: generally after $c$($\\bar c$)-medium interactions have ceased. Direct production of charmonia through hadron-hadron interactions, {\\it ie.} without explicit presence of charm quarks, occurring only at early times, is suppressed by collisions with comoving particles and accounts for some $\\sim 5\\%$ of the total J$/\\psi$ production. Coalescence is especially sensitive to the level of open charm production, scaling naively as $n_{c\\bar c}^2$. The J$/\\psi$ transverse momentum distribution is dependent on the charm quark transverse momentum distribution and early charm quark-medium interaction, thus providing a glimpse of the initial collision history.

D. E. Kahana; S. H. Kahana

2010-06-30T23:59:59.000Z

422

QuarkNet/Walta/CROP Cosmic Ray Detectors  

E-Print Network (OSTI)

QuarkNet/Walta/CROP Cosmic Ray Detectors User's Manual Jeff Rylander and Tom Jordan, Fermilab R. J. Project Development Team Fermilab: Sten Hansen, Tom Jordan, Terry Kiper Univeristy of Nebraska: Dan Claes energies. However, it is possi- ble to do high-energy physics in your school without a particle accelerator

California at Santa Cruz, University of

423

An Introduction to the Heavy Quark Effective Theory  

E-Print Network (OSTI)

These lecture notes begin with a brief survey of the physics of heavy quark systems. This discusion motivates the introduction of the Heavy Quark Effective theory (HQET) which captures a great deal of the intuition developed. A derivation of the HQET from QCD is presented as well as an analysis of its special properties. The effective theory can be seen to amount to a one-dimensional field theory in the quark sector. The heavy quark flavour- and spin- symmetry of the effective lagrangian is an offspring of this. Other topics covered include the question of covariance of the theory, the construction of interpolating fields for the heavy hadron states, the application of LSZ reduction theorems to determine the (reduced) number of form factors in flavour changing transitions, a complete verification of Luke's theorem, plus the matching conditions between QCD and the HQET beyond tree level. These are an expanded version of lectures presented during the Trieste 1994 Summer school on High Energy physics.

F. Hussain; G. Thompson

1995-02-07T23:59:59.000Z

424

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

425

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

426

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

427

HIGGS BOSON PRODUCTION IN ASSOCIATION WITH BOTTOM QUARKS.  

SciTech Connect

In the Standard Model, the coupling of the Higgs boson to b quarks is weak, leading to small cross sections for producing a Higgs boson in association with b quarks. However, Higgs bosons with enhanced couplings to b quarks, such as occur in supersymmetric models for large values of tan {beta}, will be copiously produced at both the Tevatron and the LHC in association with b quarks which will be an important discovery channel. We investigate the connections between the production channels, bg {yields} bh and gg {yields} b{bar b}h, at next-to-leading order (NLO) in perturbative QCD and present results for the case with two high-p{sub T} b jets and with one high-p{sub T} b jet at both the Tevatron and the LHC. Finally, the total cross sections without cuts are compared between gg {yields} b{bar b}h at NLO and b{bar b} {yields} h at NNLO.

DAWSON, S.; CAMPBELL, J.; DITTMAIER, S.; JACKSON, C.; KRAMER, M.; MALTONI, F.; ET AL.

2003-05-26T23:59:59.000Z

428

Influence of pions on the hadron-quark phase transition  

SciTech Connect

In this work we present the features of the hadron-quark phase transition diagrams in which the pions are included in the system. To construct such diagrams we use two different models in the description of the hadronic and quark sectors. At the quark level, we consider two distinct parametrizations of the Polyakov-Nambu-Jona-Lasinio (PNJL) models. In the hadronic side, we use a well known relativistic mean-field (RMF) nonlinear Walecka model. We show that the effect of the pions on the hadron-quark phase diagrams is to move the critical end point (CEP) of the transitions lines. Such an effect also depends on the value of the critical temperature (T{sub 0}) in the pure gauge sector used to parametrize the PNJL models. Here we treat the phase transitions using two values for T{sub 0}, namely, T{sub 0}= 270 MeV and T{sub 0}= 190 MeV. The last value is used to reproduce lattice QCD data for the transition temperature at zero chemical potential.

Lourenco, O.; Dutra, M.; Frederico, T.; Malheiro, M. [Departamento de Fisica, Instituto Tecnologico de Aeronautica-CTA, 12228-900, Sao Jose dos Campos (Brazil); Delfino, A. [Instituto de Fisica, Universidade Federal Fluminense, Av. Litoranea s/n, 24210-150, Boa Viagem, Niteroi RJ (Brazil)

2013-05-06T23:59:59.000Z

429

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

430

Unlike Particle Correlations and the Strange Quark Matter Distillation Process  

E-Print Network (OSTI)

We present a new technique for observing the strange quark matter distillation process based on unlike particle correlations. A simulation is presented based on the scenario of a two-phase thermodynamical evolution model. on leave from University of Nantes, U.M.R. Subatech

D. Ardouin; Sven Soff; C. Spieles; S. A. Bass; H. Stöcker; D. Gourio; S. Schramm; C. Greiner; R. Lednicky; V. L. Lyuboshitz; J. -p. Coffin; C. Kuhn

2002-01-01T23:59:59.000Z

431

Studies of plasma transport  

SciTech Connect

This report discusses the charge-coupled device camera and other plasma diagnostic equipment used to measure plasma density and other plasma properties. (LSP)

Malmberg, J.H.; O' Neil, T.M.; Driscoll, C.F.

1991-07-22T23:59:59.000Z

432

PLASMA DEVICE  

DOE Patents (OSTI)

A device for producing a confined high temperature plasma is described. In the device the concave inner surface of an outer annular electrode is disposed concentrically about and facing the convex outer face of an inner annular electrode across which electrodes a high potential is applied to produce an electric field there between. Means is provided to create a magnetic field perpendicular to the electric field and a gas is supplied at reduced pressure in the area therebetween. Upon application of the high potential, the gas between the electrodes is ionized, heated, and under the influence of the electric and magnetic fields there is produced a rotating annular plasma disk. The ionized plasma has high dielectric constant properties. The device is useful as a fast discharge rate capacitor, in controlled thermonuclear research, and other high temperature gas applications. (AEC)

Baker, W.R.; Brathenahl, A.; Furth, H.P.

1962-04-10T23:59:59.000Z

433

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

434

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

435

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

436

Hadron structure in a simple model of quark/nuclear matter  

SciTech Connect

We study a simple model for one-dimensional hadron matter with many of the essential features needed for examining the transition from nuclear to quark matter and the limitations of models based upon hadron rather than quark degrees of freedom. The dynamics are generated entirely by the quark confining force and exchange symmetry. Using Monte Carlo techniques, the ground-state energy, single-quark momentum distribution, and quark correlation function are calculated for uniform matter as a function of density. The quark confinement scale in the medium increases substantially with increasing density. This change is evident in the correlation function and momentum distribution, in qualitative agreement with the changes observed in deep-inelastic lepton scattering. Nevertheless, the ground-state energy is smooth throughout the transition to quark matter and is described remarkably well by an effective hadron theory based on a phenomenological hadron-hadron potential.

Horowitz, C.J.; Moniz, E.J.; Negele, J.W.

1985-04-01T23:59:59.000Z

437

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

438

Burning plasmas  

SciTech Connect

The fraction of fusion-reaction energy that is released in energetic charged ions, such as the alpha particles of the D-T reaction, can be thermalized within the reacting plasma and used to maintain its temperature. This mechanism facilitates the achievement of very high energy-multiplication factors Q, but also raises a number of new issues of confinement physics. To ensure satisfactory reaction operation, three areas of energetic-ion interaction need to be addressed: single-ion transport in imperfectly symmetric magnetic fields or turbulent background plasmas; energetic-ion-driven (or stabilized) collective phenomena; and fusion-heat-driven collective phenomena. The first of these topics is already being explored in a number of tokamak experiments, and the second will begin to be addressed in the D-T-burning phase of TFTR and JET. Exploration of the third topic calls for high-Q operation, which is a goal of proposed next-generation plasma-burning projects. Planning for future experiments must take into consideration the full range of plasma-physics and engineering R D areas that need to be addressed on the way to a fusion power demonstration.

Furth, H.P.; Goldston, R.J.; Zweben, S.J. (Princeton Univ., NJ (USA). Plasma Physics Lab.); Sigmar, D.J. (Massachusetts Inst. of Tech., Cambridge, MA (USA))

1990-10-01T23:59:59.000Z

439

Gamma-Ray Bursts and Dark Matter - a joint origin?  

E-Print Network (OSTI)

A scenario is presented where large quark-gluon plasma (QGP) objects escaping the quark-hadron transition in the early Universe account for the baryonic dark matter as well as act as the sources for gamma-ray bursts. Two basic assumptions are made. Firstly, we assume that a QGP consisting of u,d and s quarks is the absolute ground state of QCD and secondly, that the quark-hadron transition in the early Universe was of first order. Both particle physics and astrophysics constraints are discussed, mainly from an observational point of view.

Daniel Enstrom

1998-10-13T23:59:59.000Z

440

Synchrotron radiation by fast fermions in heavy-ion collisions  

SciTech Connect

We study the synchrotron radiation of gluons by fast quarks in strong magnetic field produced by colliding relativistic heavy ions. We argue that due to high electric conductivity of plasma, the magnetic field is almost constant during the entire plasma lifetime. We calculate the energy loss due to synchrotron radiation of gluons by fast quarks. We find that the typical energy loss per unit length for a light quark at the Large Hadron Collider is a few GeV per fm. This effect alone predicts quenching of jets with p{sub perpendicular} up to about 20 GeV. We also show that the spin-flip transition effect accompanying the synchrotron radiation leads to a strong polarization of quarks and leptons with respect to the direction of the magnetic field. Observation of the lepton polarization may provide a direct evidence of existence of strong magnetic field in heavy-ion collisions.

Tuchin, Kirill [Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States) and RIKEN BNL Research Center, Upton, New York 11973-5000 (United States)

2010-09-15T23:59:59.000Z

Note: This page contains sample records for the topic "quark gluon plasma" 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.


441

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

442

Electric charge fluctuations in central Pb+Pb collisions at 20, 30, 40, 80 and 158 AGeV  

E-Print Network (OSTI)

Results are presented on event-by-event electric charge fluctuations in central Pb+Pb collisions at 20, 30, 40, 80 and 158 AGeV. The observed fluctuations are close to those expected for a gas of pions correlated by global charge conservation only. These fluctuations are considerably larger than those calculated for an ideal gas of deconfined quarks and gluons. The present measurements do not necessarily exclude reduced fluctuations from a quark-gluon plasma because these might be masked by contributions from resonance decays.

NA49 Collaboration

2004-06-11T23:59:59.000Z

443

16. Heavy-Quark and Soft-Collinear Effective Theory 1 16. Heavy-Quark and Soft-Collinear Effective Theory  

E-Print Network (OSTI)

16. Heavy-Quark and Soft-Collinear Effective Theory 1 16. Heavy-Quark and Soft-Collinear Effective the quantum fluctuations of such heavy particles are "integrated out" from the generating functional integral. Beringer et al.(PDG), PR D86, 010001 (2012) (http://pdg.lbl.gov) June 18, 2012 16:19 #12;2 16. Heavy

444

Study of Chemical Equilibration of a Baryon Rich QGP  

E-Print Network (OSTI)

Parton equilibration studies for thermally equilibrated but chemically non-equilibrated quark-gluon-plasma (QGP), likely to be formed at the relativistic colliders at BNL and CERN is presented.Parton equilibration is studied enforcing baryon number conservation. Process like quark-flavor interchanging is also taken into consideration.The degree of equilibration is studied comparatively for the various reactions/ constraints that are being considered.

Abhijit Sen

2008-02-26T23:59:59.000Z

445

RHIC physics overview  

E-Print Network (OSTI)

The results from data taken during the last several years at the Relativistic Heavy-Ion Collider (RHIC) will be reviewed in the paper. Several selected topics that further our understanding of constituent quark scaling, jet quenching and color screening effect of heavy quarkonia in the hot dense medium will be presented. Detector upgrades will further probe the properties of Quark Gluon Plasma. Future measurements with upgraded detectors will be presented. The discovery perspectives from future measurements will also be discussed.

Lijuan Ruan

2010-07-16T23:59:59.000Z

446

Lectures on the gauge/string duality with emphasis on spectroscopy  

Science Conference Proceedings (OSTI)

I review recent progress on the connection between string theory and quantum chromo-dynamics in the context of the gauge/string duality. Emphasis is placed on conciseness and conceptual aspects rather than on technical details. Topics covered include the large-N{sub c} limit of gauge theories, the gravitational description of gauge theory thermodynamics and hydrodynamics, and the physics of quarks and mesons in the quark-gluon plasma.

Mateos, David [Institucio Catalana de Recerca i Estudis Avancats (ICREA), Barcelona (Spain) and Departament de Fisica Fonamental and Institut de Ciencies del Cosmos, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona (Spain)

2010-11-12T23:59:59.000Z

447

The electromagnetic calorimeter for the STAR experiment at RHIC  

SciTech Connect

The STAR detector at RHIC can be used both for searches for quark-gluon plasma and for high energy pp spin physics. An electromagnetic calorimeter is being planned which will be used for triggering on High pt direct gammas, e[sup [plus minus

Underwood, D.G.

1992-01-01T23:59:59.000Z

448

Microsoft Word - QuarkNet Friday Flyer.docx  

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

Flyer, March 15, 2013 SPECIAL EDITION Flyer, March 15, 2013 SPECIAL EDITION QuarkNet Workshops Since 1999, QuarkNet has introduced teachers to inquiry-based investigations using particle physics data. Select workshops from this menu for your center programs. Contacts can answer your questions and schedule a workshop. Teaching and Learning Workshop (2-3 days) - Contact Tom: jordant@fnal.gov This workshop introduces teachers to inquiry-based resources that incorporate particle physics content. We tailor this workshop to the needs and interests of the center and provide teachers with investigations that can be used in a high school classroom. The following workshops prepare teachers to facilitate data analysis for students, from scaffolding to investigation and reporting using different datasets.

449

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

450

Color symmetrical superconductivity in a schematic nuclear quark model  

E-Print Network (OSTI)

In this note, a novel BCS-type formalism is constructed in the framework of a schematic QCD inspired quark model, having in mind the description of color symmetrical superconducting states. The physical properties of the BCS vacuum (average numbers of quarks of different colors) remain unchanged under an arbitrary color rotation. In the usual approach to color superconductivity, the pairing correlations affect only the quasi-particle states of two colors, the single particle states of the third color remaining unaffected by the pairing correlations. In the theory of color symmetrical superconductivity here proposed, the pairing correlations affect symmetrically the quasi-particle states of the three colors and vanishing net color-charge is automatically insured. It is found that the groundstate energy of the color symmetrical sector of the Bonn model is well approximated by the average energy of the color symmetrical superconducting state proposed here.

Henrik Bohr; João da Providência

2009-09-14T23:59:59.000Z

451

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

452

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

453

Higgs Boson Resummation via Bottom-Quark Fusion  

E-Print Network (OSTI)

The region of small transverse momentum in q-qbar- and gg-initiated processes must be studied in the framework of resummation to account for the large, logarithmically-enhanced contributions to physical observables. In this letter, we study resummed differential cross-sections for Higgs production via bottom-quark fusion. We find that the differential distribution peaks at approximately 15 GeV, a number of great experimental importance to measuring this production channel.

B. Field

2004-07-21T23:59:59.000Z

454

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

455

Quark flavor mixing, CP violation, and all that  

SciTech Connect

We review the present state of knowledge of the mixing of quark flavors under weak interactions and the associated explanation of CP violation inherent in the single nontrivial phase present in the three-generation mixing matrix. In this context we present the phenomenological basis for the increasing possibility that large CP violation asymmetries can be experimentally observed in the B meson system. 39 refs., 11 figs.,

Gilman, F.J.

1988-04-01T23:59:59.000Z

456

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

457

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

458

Numerical simulation of the hydrodynamical combustion to strange quark matter  

Science Conference Proceedings (OSTI)

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

Niebergal, Brian; Ouyed, Rachid [Department of Physics and Astronomy, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4 (Canada); Jaikumar, Prashanth [Department of Physics and Astronomy, California State University Long Beach, 1250 Bellflower Blvd., Long Beach, California 90840 (United States); Institute of Mathematical Sciences, C.I.T. Campus, Chennai, TN 600113 (India)

2010-12-15T23:59:59.000Z

459

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

460

Flavor Asymmetry of the Nucleon Sea and the Five-Quark Components of the Nucleons  

Science Conference Proceedings (OSTI)

The existence of the five-quark Fock states for the intrinsic charm quark in the nucleons was suggested some time ago, but conclusive evidence is still lacking. We generalize the previous theoretical approach to the light-quark sector and study possible experimental signatures for such five-quark states. In particular, we compare the d-u and u+d-s-s data with the calculations based on the five-quark Fock states. The qualitative agreement between the data and the calculations is interpreted as evidence for the existence of the intrinsic light-quark sea in the nucleons. The probabilities for the |uuduu> and |uuddd> Fock states are also extracted.

Chang, Wen-Chen [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Peng, Jen-Chieh [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

2011-06-24T23:59:59.000Z

Note: This page contains sample records for the topic "quark gluon plasma" 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.


461

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

462

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

463

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

464

Systematic Study of Charm Quark Energy Loss Using Parton Cascade Model  

E-Print Network (OSTI)

In this paper we use a Parton Cascade Model to study the evolution of charm quarks propagating through a thermal brick of QCD matter. We determine the energy loss and the transport coefficient 'qhat' for charm quarks. The calculations are done for constant temperature of 350 MeV and the results are compared to analytical calculations of heavy quark energy loss in order to validate the applicability of using a Parton Cascade Model for the study of heavy quark dynamics in hot and dense QCD matter.

Mohammed Younus; Christopher E. Coleman-Smith; Steffen A. Bass; Dinesh K. Srivastava

2013-09-05T23:59:59.000Z

465

The Particle Adventure | How do we interpret our data? | A quark...  

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

A quarkgluon event In these pictures e- and e+ beams, perpendicular to the screen, met and annihilated. The resulting quarks and antiquarks combined to produce mesons and baryons,...

466

Chiral transition and deconfinement transition in QCD with the highly improved staggered quark (HISQ) action  

Science Conference Proceedings (OSTI)

We report preliminary results on the chiral and deconfinement aspects of the QCD transition at finite temperature using the Highly Improved Staggered Quark (HISQ) action on lattices with temporal extent of N{sub {tau}} = 6 and 8. The chiral aspects of the transition are studied in terms of quark condensates and the disconnected chiral susceptibility. We study the deconfinement transition in terms of the strange quark number susceptibility and the renormalized Polyakov loop. We made continuum estimates for some quantities and find reasonably good agreement between our results and the recent continuum extrapolated results obtained with the stout staggered quark action.

Petreczky P.; Bazavov, A.

2011-10-11T23:59:59.000Z

467

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

468

Non-Abelian dual superconductivity and Gluon propagators in the deep IR region for SU(3) Yang-Mills theory  

E-Print Network (OSTI)

We have proposed the non-Abelian dual superconductivity picture for quark confinement in the SU(3) Yang-Mills (YM) theory, and have given numerical evidences for the restricted-field dominance and the non-Abelian magnetic monopole dominance in the string tension by applying a new formulation of the YM theory on a lattice. To establish the non-Abelian dual superconductivity picture for quark confinement, we have observed the non-Abelian dual Meissner effect in the SU(3) Yang-Mills theory by measuring the chromoelectric flux created by the quark-antiquark source, and the non-Abelian magnetic monopole currents induced around the flux. We conclude that the dual superconductivity of the SU(3) Yang-Mills theory is strictly the type I and that this type of dual superconductivity is reproduced by the restricted field and the non-Abelian magnetic monopole part, in sharp contrast to the SU(2) case: the border of type I and type II.

Akihiro Shibata; Kei-Ichi Kondo; Seikou Kato; Toru Shinohara

2013-02-27T23:59:59.000Z

469

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

470

Collinear and soft-gluon corrections to Higgs production at next-to-next-to-next-to-leading order  

SciTech Connect

I present analytical expressions for the collinear and soft-gluon corrections to Higgs production via the process bb{yields}H as well as gg{yields}H through next-to-next-to-next-to-leading order (NNNLO). The soft corrections are complete, while the collinear corrections include leading and some subleading logarithms. Numerical results at the Tevatron and the CERN LHC are presented, primarily for bb{yields}H. It is shown that the collinear terms greatly improve the soft and virtual approximation at next-to-leading order and next-to-next-to-leading order, especially when subleading terms are included. The NNNLO collinear and soft corrections provide significant enhancements to the total cross section. I also provide expressions for the collinear and soft corrections through NNNLO for the related Drell-Yan process.

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

2008-03-01T23:59:59.000Z