11,226 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
Toward the Global Structure of Conformal Theories in the SU(3) Gauge Theory
We introduce a new concept "conformal theories with an IR cutoff", after
pointing out that the following two categories in SU(3) gauge theories with
fundamental N_f fermions possess an IR fixed point: Large N_f QCD with N_f in
the conformal window (referred as Conformal QCD) and small N_f QCD with N_f out
of the conformal window at temperature T/Tc > 1 (referred as High Temperature
QCD).
In the conformal theories with an IR cutoff there exists the "conformal
region'" together with the confining region and the deconfining region. We
verify numerically on a lattice of the size 16^3 x64 the existence of the
conformal region and the non-trivial Z(3) structure of the vacuum and the
Yukawa-type decay form of meson propagators in the conformal region.
We stress that High Temperature QCD is intrinsically accompanied with an IR
cutoff. Therefore the understanding the vacuum structure and the property of
correlation functions is the key to resolve long standing issues in High
Temperature QCD.
We further argue that there is a precise correspondence between Conformal QCD
and High Temperature QCD in the temporal propagators under the change of the
parameters N_f and T/T_c respectively: the one boundary is close to meson
states and the other is close to free quark states.
In particular, we find the correspondence between Conformal QCD with N_f = 7
and High Temperature QCD with N_f=2 at T ~ 2 Tc being in close relation to a
meson unparticle model. From this we estimate the anomalous mass dimension
gamma* = 1.2 (1) for N_f=7.Comment: 7 pages, 5 figures, based on the work in collaboration with K. -I
Ishikawa, Yu Nakayama and T. Yoshie, presented at the 31st International
Symposium on Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013,
Mainz, German
Computers for Lattice Field Theories
Parallel computers dedicated to lattice field theories are reviewed with
emphasis on the three recent projects, the Teraflops project in the US, the
CP-PACS project in Japan and the 0.5-Teraflops project in the US. Some new
commercial parallel computers are also discussed. Recent development of
semiconductor technologies is briefly surveyed in relation to possible
approaches toward Teraflops computers.Comment: 15 pages with 16 PS figures, review presented at Lattice 93, LaTeX
(espcrc2.sty required
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
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
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
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