3,405 research outputs found
Equation of state in 2+1 flavor QCD with improved Wilson quarks by the fixed scale approach
We study the equation of state in 2+1 flavor QCD with nonperturbatively
improved Wilson quarks coupled with the RG-improved Iwasaki glue. We apply the
-integration method to nonperturbatively calculate the equation of state by
the fixed-scale approach. With the fixed-scale approach, we can purely vary the
temperature on a line of constant physics without changing the system size and
renormalization constants. Unlike the conventional fixed- approach, it is
easy to keep scaling violations small at low temperature in the fixed scale
approach. We study 2+1 flavor QCD at light quark mass corresponding to
, while the strange quark mass is chosen around the
physical point. Although the light quark masses are heavier than the physical
values yet, our equation of state is roughly consistent with recent results
with highly improved staggered quarks at large .Comment: 14 pages, 12 figures, v2: Table I and Figure 3 are corrected,
reference updated. Main discussions and conclusions are unchanged, v3:
version to appear in PRD, v4: reference adde
Towards the QCD equation of state at the physical point using Wilson fermion
We study the (2+1)-flavor QCD at nonzero temperatures using nonperturbatively
improved Wilson quarks of the physical masses by the fixed scale approach. We
perform physical point simulations at finite temperatures with the coupling
parameters which were adopted by the PACS-CS Collaboration in their studies
using the reweighting technique. Zero temperature values are obtained on the
PACS-CS configurations which are open to the public on the ILDG/JLDG. Finite
temperature configurations are generated with the RHMC algorithm. The lattice
sizes are with , 13, , 4 which correspond to
--550 MeV. We present results of some basic observables at these
temperatures and the status of our calculation of the equation of state.Comment: 7 pages, 3 figures, proceedings of the 33rd International Symposium
on Lattice Field Theory, July 14-18, 2015, Kobe, Japa
Quantum Chromodynamics with Many Flavors
We investigate the phase structure of lattice QCD for general number of
flavors . Based on numerical data combined with the results of the
perturbation theory we propose the following picture: When , there
is only one IR fixed point at vanishing gauge coupling, i.e., the theory in the
continuum limit is trivial. On the other hand, when , there
is a non-trivial fixed point. Therefore, the theory is non-trivial with
anomalous dimensions, however, without quark confinement. Theories which
satisfy both quark confinement and spontaneous chiral symmetry breaking in the
continuum limit exist only for .Comment: Talk presented by K. Kanaya at the 1997 Yukawa International Seminar
(YKIS'97) on ``Non-Perturbative QCD --- Structure of the QCD Vacuum ---'',
YITP, Kyoto, Japan, 2--12 Dec. 1997. To be published in the proceedings
[Prog. Theor. Phys. Suppl.
Phase structure of QCD for general number of flavors
We investigate and elucidate the phase structure of QCD for general number of
flavors with Wilson quarks, varying from 2 up to 300. Based on
numerical results combined with the result of the perturbation theory we
propose the following picture: When , there is only a trivial fixed
point and therefore the theory in the continuum limit is trivial. On the other
hand, when , there is a non-trivial fixed point and therefore
the theory is non-trivial with anomalous dimensions, however, without quark
confinement. Theories which satisfy both quark confinement and spontaneous
chiral symmetry breaking in the continuum limit exist only for . We
also discuss the structure of the deconfining phase at finite temperatures for
the small number of flavors such as and 3, through a systematic study
of it for general number of flavors.Comment: LaTeX, 7 pages, 10 PS figures, Talk presented at LATTICE96(poster)
and LATTICE96(finite temperature
Application of fixed scale approach to static quark free energies in quenched and 2+1 flavor lattice QCD with improved Wilson quark action
Free energies between static quarks and Debye screening masses in the
quark-gluon plasma are studied on the basis of Polyakov-line correlations in
lattice simulations of 2+1 flavors QCD with the renormalization-group improved
gluon action and the -improved Wilson quark action. We perform
simulations at (0.74) for light (strange) flavors
with lattice sizes of with --12. We adopt the
fixed-scale approach, where temperature can be varied without changing the
spatial volume and renormalization factor. We find that, at short distance, the
free energies of static quarks in color-singlet channel converge to the
static-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 free energies of static quarks approach to
twice the single-quark free energies, implying that the interaction between
static quarks is fully screened. The screening properties can be well described
by the screened Coulomb form with appropriate Casimir factor at high
temperature. We also discuss a limitation of the fixed-scale approach at high
temperature.Comment: 16 pages, 14 figure
Scaling of the critical temperature and quark potential with a renormalization group improved SU(3) gauge action
We study the scaling property of the ratio of the critical temperature
to the square root of the string tension in the SU(3) pure gauge
theory using a renormalization group improved action. We first determine the
critical coupling on lattices with temporal extension and 6,
and then calculate the static quark potential at the critical couplings on
lattices at zero temperature. The values of in the
infinite volume limit are identical within errors, while they are slightly
larger than the value extrapolated to the continuum limit with the standard
action. We also note that the rotational invariance of the static quark
potential is remarkably restored in the both cases, and that the potential
in physical units scales in the whole region of investigated.Comment: 3 pages of Latex, 5 PostScript figures, Talk presented at
LATTICE96(finite temperature
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