658 research outputs found
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
Anisotropic Improved Actions
The studies of the quantum corrections for the anisotropy
parameter,, for the improved actions, , are proceeded in the medium to strong coupling
region on anisotropic lattices. The global features for the parameters
as a function of and the coefficient have been clarified. It
has been found by the perturbative analysis that as decreases, the slope
of the becomes less steep and for the actions whose is
less than -0.160, decreases as decreases, contrary to the case
of the standard action. In the medium to strong coupling region, the
parameter begins to increase as decreases for all . This means
that for the actions with , the one-loop perturbative results
for break down qualitatively and the parameters have a dip. As a
result of this dip structure the for Iwasaki's action remains close to
unity in the wide range of .Comment: LATTICE99(hightemp), 3 pages in latex, 4 Postscript 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
Numerical Results for Transport Coefficients of Quark Gluon Plasma with Iwasaki's Improved Action
Numerical results for the transport coefficients of quark gluon plasma are
calculated by lattice simulation of SU(3) pure gauge model. The bulk viscosity
is consistent with zero. The shear viscosity is finite and increases with
temperature roughly as , and around the finite temperature
transition points, it is slightly smaller than the typical hadron masses.Comment: Talk presented at LATTICE97(Finite Temperature and Density), 3 pages
in latex, 4 Postscript figure
Improved Gauge Actions on Anisotropic Lattices I
On anisotropic lattices with the anisotropy the
following basic parameters are calculated by perturbative method: (1) the
renormalization of the gauge coupling in spatial and temporal directions,
and , (2) the parameter, (3) the ratio of the
renormalized and bare anisotropy and (4) the derivatives of
the coupling constants with respect to , and . We employ the improved gauge
actions which consist of plaquette and six-link rectangular loops, . This class of actions
covers Symanzik, Iwasaki and DBW2 actions. The ratio shows an impressive
behavior as a function of , i.e., for the standard Wilson and
Symanzik actions, while for Iwasaki and DBW2 actions. This is
confirmed non-perturbatively by numerical simulations in weak coupling regions.
The derivatives and also changes sign as increases. For
Iwasaki and DBW2 actions they become opposite sign to those for standard and
Symanzik actions. However, their sum is independent of the type of actions due
to Karsch's sum rule
Equation of state in the PNJL model with the entanglement interaction
The equation of state and the phase diagram in two-flavor QCD are
investigated by the Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model
with an entanglement vertex between the chiral condensate and the
Polyakov-loop. The entanglement-PNJL (EPNJL) model reproduces LQCD data at zero
and finite chemical potential better than the PNJL model. Hadronic degrees of
freedom are taken into account by the free-hadron-gas (FHG) model with the
volume-exclusion effect due to the hadron generation. The EPNJL+FHG model
improves agreement of the EPNJL model with LQCD data particularly at small
temperature. The quarkyonic phase survives, even if the correlation between the
chiral condensate and the Polyakov loop is strong and hadron degrees of freedom
are taken into account. However, the location of the quarkyonic phase is
sensitive to the strength of the volume exclusion.Comment: 9 pages, 7 figure
Measurement of a small atmospheric ratio
From an exposure of 25.5~kiloton-years of the Super-Kamiokande detector, 900
muon-like and 983 electron-like single-ring atmospheric neutrino interactions
were detected with momentum MeV/, MeV/, and
with visible energy less than 1.33 GeV. Using a detailed Monte Carlo
simulation, the ratio was measured to be , consistent with previous results from the
Kamiokande, IMB and Soudan-2 experiments, and smaller than expected from
theoretical models of atmospheric neutrino production.Comment: 14 pages with 5 figure
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