38,249 research outputs found
Status of the CP-PACS Project
The CP-PACS computer with a peak speed of 300 Gflops was completed in March
1996 and has started to operate. We describe the final specification and the
hardware implementation of the CP-PACS computer, and its performance for QCD
codes. A plan of the grade-up of the computer scheduled for fall of 1996 is
also given.Comment: Talk presented at LATTICE96(machines), 3 pages including 5 PS figure
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
Finite Temperature Transition in Two Flavor QCD with Renormalization Group Improved Action
The finite temperature transition or crossover in QCD with two degenerate
Wilson quarks is investigated using a renormalization group improved action. At
and 2.1 where GeV, the expectation value of
the Polyakov loop and the pion screening mass on an lattice vary
smoothly with the hopping parameter through the transition/crossover. The quark
screening mass in the high temperature phase agrees well with that in the low
temperature phase calculated on an lattice. The smooth transition of the
observables is totally different from the sharp transition found for the
standard action at and 5.1 where is also GeV.Comment: 3 pages, latex, 2 postscript figures. Contribution to Lattice 94
proceeding
Phase Diagram of QCD at Finite Temperatures with Wilson Fermions
Phase diagram of QCD with Wilson fermions for various numbers of flavors
is discussed. Our simulations mainly performed on a lattice with the
temporal size indicate the following: The chiral phase transition is
of first order when , while it is continuous when . For
the realistic case of massless u and d quarks and the strange quark with MeV, the phase transition is first order. The sharp transition in the
intermediate mass region for at observed by the MILC group
disappears when an RG improvement is made for the pure gauge action.Comment: ps file, 7 pages with 5 figures, contribution to Lattice 94
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
Non-equilibrium and non-linear stationary state in thermoelectric materials
Efficiency of thermoelectric materials is characterized by the figure of
merit Z. Z has been believed to be a peculiar material constant. However, the
accurate measurements in the present work reveal that Z has large size
dependence and a non-linear temperature distribution appears as stationary
state in the thermoelectric material. The observation of these phenomena is
achieved by the Harman method. This method is the most appropriate way to
investigate the thermoelectric properties because the dc and ac resistances are
measured by the same electrode configuration. We describe the anomalous
thermoelectric properties observed in mainly (Bi,Sb)2Te3 by the Harman method
and then insist that Z is not the peculiar material constant but must be
defined as the physical quantity dependent of the size and the position in the
material.Comment: 9 pages, 4 figures. submitted to Applied Physics Lette
QCD hadron spectrum with domain wall fermions
We present the QCD hadron spectrum for the cases of both quenched and
two-flavor dynamical domain wall fermions. We compare the results obtained
using the Wilson gauge action and a renormalization group improved gauge
action. Finite volume effects and the dependence on the finite extent of the
fifth dimension are discussed.Comment: LATTICE99(QCD spectrum), 3 pages, 2 figures. Work done with CU and
RIKEN/BNL/CU collaboratio
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
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