12,662 research outputs found
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
Quantum chromodynamics with various number of flavors
The phase structure of QCD with various number of flavors is studied for
Wilson quarks. For the case of we find that the finite temperature
deconfining transition is of first order in the chiral limit on an
lattice. Together with our previous results that the deconfining transition in
the chiral limit is continuous for and is first order for , the
order of the transition is found to be consistent with a prediction of
universality. The case of QCD is also studied in the strong coupling
limit and the phase structure is found to be quite similar to the case of
: There exists a critical number of flavors and for the confinement is broken even in the strong coupling limit for light
quarks. corresponding to 7 for .Comment: 3 pages with 5 PS figures, LaTeX (espcrc2.sty required), UTHEP-26
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
High statistics calculations of quenched QCD spectrum using various quark sources
We present the results for the hadron spectrum calculated on 400
configurations using point source, wall source and 8-cubic sources, in quenched
QCD with Wilson fermions at and on a
lattice. The results for the ground state masses obtained with three types of
quark sources agree well with each other. Masses of the first excited states
appear consistent with experimental values within large errors.Comment: 3 pages, 2 postscript figures, to appear in the Proceedings of
LATTICE 93, Dallas, USA; preprint UTHEP-26
Anisotropic Improved Gauge Actions; --Perturbative and Numerical Studies --
The parameter on the anisotropic lattice, the spatial and
temperature coupling constant , and their derivative
with respaect to the the anisotropy parameter are studied perturbatively
for the class of improved actions, which cover tree level Symanzik's, Iwasaki's
and QCDTARO's improved actions. The becomes less
than 1 for Iwasaki's and QCDTARO's action, which is confirmed nonperturbatively
by numerical simulations. Derivatives of the coupling constants with respect to
the anisotropy parameter, and , change sign for those improved actions.Comment: LATTICE98(hightemp), 3 pages in latex, 4 Postscript figures Fonts in
Fig3 is replaced Aria
Chiral Phase Transition in Lattice QCD with Wilson Quarks
The nature of the chiral phase transition in lattice QCD is studied for the
cases of 2, 3 and 6 flavors with degenerate Wilson quarks, mainly on a lattice
with the temporal direction extension . We find that the chiral phase
transition is continuous for the case of 2 flavors, while it is of first order
for 3 and 6 flavors.Comment: uuencoded compressed tar file, LaTeX, 14 pages, 7 figure
Transport Coefficients of Quark Gluon Plasma From Lattice Gauge Theory
Numerical results for the transport coefficients of quark gluon plasma are
obtained by lattice simulations on on lattice with the quench
approximation where we apply the gauge action proposed by Iwasaki. The bulk
viscosity is consistent with zero, and the shear viscosity is slightly smaller
than the typical hadron masses. They are not far from the simple extrapolation
on the figure of perturbative calculation in high temperature limit down to . The gluon propagator in the confined and deconfined phases are
also discussed.Comment: Quark Matter 97(talk at parallel session QCD) 4 pages in latex, 4
Postscript figure
Hadron spectroscopy and static quark potential in full QCD: A comparison of improved actions on the CP-PACS
We present first results from a full QCD calculation on the CP-PACS,
comparing various actions at and --0.9. We use the plaquette and a renormalization group improved action for
the gluons, and the Wilson and the SW-Clover action for quarks. We find that
significant improvements in the hadron spectrum results from improving the
quarks, while the gluon improvement is required for a rotationally invariant
static potential. An ongoing effort towards exploring the chiral limit in full
QCD is described.Comment: 6 pages, based on talks presented by R. Burkhalter and T. Kaneko at
Lattice97, Edinburg
Finite-temperature chiral transitions in QCD with the Wilson quark action
We investigate the finite-temperature phase structure and the scaling of the
chiral condensate in lattice QCD with two degenerate light quarks, using a
renormalization group improved gauge action and the Wilson quark action. We
obtain a phase diagram which is consistent with that from the parity-flavor
breaking scenario. The scaling relation for the chiral condensate assuming the
critical exponents and the scaling function of the three dimensional O(4) model
is remarkably satisfied for a wide range of parameters. This indicates that the
chiral transition in two flavor QCD is of second order in the continuum limit.Comment: LaTeX, 3 pages, 4 EPS figures, Talk presented at LATTICE97 (finite
temperature
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