268 research outputs found
Thermodynamics and heavy-quark free energies at finite temperature and density with two flavors of improved Wilson quarks
Thermodynamics of two-flavor QCD at finite temperature and density is studied
on a lattice, using a renormalization group improved gauge
action and the clover improved Wilson quark action. In the simulations along
lines of constant , we calculate the Taylor expansion
coefficients of the heavy-quark free energy with respect to the quark chemical
potential () up to the second order. By comparing the expansion
coefficients of the free energies between quark()and antiquark(),
and between and , we find a characteristic difference at finite
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.Comment: Talk given at the XXV International Symposium on Lattice Field Theory
(Lattice 2007), July 30 - August 4, 2007, Regensburg, German
Static quark free energies at finite temperature with two flavors of improved Wilson quarks
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
lattice, we extract the free energies, the effective running coupling and the Debye screening mass 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 . Also we made a comparison between our results with the Wilson quark
and those with the staggered quark previously reported.Comment: 7 pages, 9 figures, talk given at Lattice 2006 (high temperature and
density
Finite temperature phase transition of two-flavor QCD with an improved Wilson quark action
We study the phase structure of QCD at finite temperatures with two flavors
of dynamical quarks on a lattice with the size , using a renormalization group improved gauge action and a clover improved
Wilson quark action. The simulations are made along the lines of constant
physics determined in terms of at zero-temperature. We
show preliminary results for the spatial string tension in the high temperature
phase.Comment: 7 pages, 7 figures, talk presented at Lattice 2006 (high temperature
and density
Equation of state at finite density in two-flavor QCD with improved Wilson quarks
We study the equation of state in two-flavor QCD at finite temperature and
density. Simulations are made with the RG-improved gluon action and the
clover-improved Wilson quark action. Along the lines of constant physics for
and 0.80, we compute the derivatives of the quark
determinant with respect to the quark chemical potential up to the
fourth order at . We adopt several improvement techniques in the
evaluation. We study thermodynamic quantities and quark number susceptibilities
at finite using these derivatives. We find enhancement of the quark
number susceptibility at finite , in accordance with previous
observations using staggered-type quarks. This suggests the existence of a
nearby critical point.Comment: 7 pages, 16 figures, presented at the XXVI International Symposium on
Lattice Field Theory (LATTICE 2008), July 14-19, 2008, Williamsburg,
Virginia, US
Heavy-Quark Free Energy, Debye Mass, and Spatial String Tension at Finite Temperature in Two Flavor Lattice QCD with Wilson Quark Action
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 lattice. From the
line of constant physics at and 0.80, we extract
the heavy-quark free energies, the effective running coupling
and the Debye screening mass 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 . 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.Comment: 25 pages, 37 EPS figure
Full QED+QCD Low-Energy Constants through Reweighting
The effect of sea quark electromagnetic charge on meson masses is
investigated, and first results for full QED+QCD low-energy constants are
presented. The electromagnetic charge for sea quarks is incorporated in
quenched QED+full QCD lattice simulations by a reweighting method. The
reweighting factor, which connects quenched and unquenched QED, is estimated
using a stochastic method on 2+1 flavor dynamical domain-wall quark ensembles.Comment: 5 pages, 9 figures, REVTeX 4.1, v2: published versio
Electric and Magnetic Screening Masses at Finite Temperature from Generalized Polyakov-Line Correlations in Two-flavor Lattice QCD
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 () 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 supersymmetric Yang-Mills theory
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