2,286 research outputs found
Quantum Monte Carlo study of the transverse-field Ising model on a frustrated checkerboard lattice
We present the numerical results for low temperature behavior of the
transverse-field Ising model on a frustrated checkerboard lattice, with focus
on the effect of both quantum and thermal fluctuations. Applying the
recently-developed continuous-time quantum Monte Carlo algorithm, we compute
the magnetization and susceptibility down to extremely low temperatures while
changing the magnitude of both transverse and longitudinal magnetic fields.
Several characteristic behaviors are observed, which were not inferred from the
previously studied quantum order from disorder at zero temperature, such as a
horizontal-type stripe ordering at a substantial longitudinal field and a
persistent critical behavior down to low temperature in a weak longitudinal
field region.Comment: 6 pages, 5 figures, accepted for publication in J. Phys.: Conf. Se
Thermally-induced magnetic phases in an Ising spin Kondo lattice model on a kagome lattice at 1/3-filling
Numerical investigation on the thermodynamic properties of an Ising spin
Kondo lattice model on a kagome lattice is reported. By using Monte Carlo
simulation, we investigated the magnetic phases at 1/3-filling. We identified
two successive transitions from high-temperature paramagnetic state to a
Kosterlitz-Thouless-like phase in an intermediate temperature range and to a
partially disordered phase at a lower temperature. The partially disordered
state is characterized by coexistence of antiferromagnetic hexagons and
paramagnetic sites with period . We compare the results
with those for the triangular lattice case.Comment: 4 pages, 2 figure
Charmonium spectroscopy with heavy Kogut-Susskind quarks
Charmonium spectroscopy with Kogut-Susskind valence quarks are carried out
for quenched QCD at and for two-flavor full QCD at .
Results for 1P--1S mass splitting and estimates of
are reported. Problems associated with
flavor breaking effects and finite size effects of states are discussed.Comment: 3 pages, contribution to the Lattice '94 conference, uuencoded
compressed ps-fil
Sea Quark Effects on the Strong Coupling Constant
We present results showing that the strong coupling constant measured in
two-flavor full QCD with dynamical Kogut-Susskind quarks at exhibit
a 15\% increase due to sea quarks over that for quenched QCD at the scale
GeV . (talk at lattice93)Comment: 3 pages, compressed, uuencoded PostScript file(name:lat93ch.ps.Z
Finite-Size Effect of Hadron Masses with Kogut-Susskind Quarks
We present numerical results and their analyses of finite-size effects of
hadron masses for both quenched and full QCD calculations. We show that they
are much larger for full QCD due to dynamical sea quarks and the associated
breaking of symmetry. We also argue that finite-size effects are
non-negligible even for the largest lattice size simulation currently being
made for a very small quark mass. (talk at lattice93)Comment: 4 pages, compressed, uuencoded PostScript file(name:lat93.ps.Z
Tables of Hyperonic Matter Equation of State for Core-Collapse Supernovae
We present sets of equation of state (EOS) of nuclear matter including
hyperons using an SU_f(3) extended relativistic mean field (RMF) model with a
wide coverage of density, temperature, and charge fraction for numerical
simulations of core collapse supernovae. Coupling constants of Sigma and Xi
hyperons with the sigma meson are determined to fit the hyperon potential
depths in nuclear matter, U_Sigma(rho_0) ~ +30 MeV and U_Xi(rho_0) ~ -15 MeV,
which are suggested from recent analyses of hyperon production reactions. At
low densities, the EOS of uniform matter is connected with the EOS by Shen et
al., in which formation of finite nuclei is included in the Thomas-Fermi
approximation. In the present EOS, the maximum mass of neutron stars decreases
from 2.17 M_sun (Ne mu) to 1.63 M_sun (NYe mu) when hyperons are included. In a
spherical, adiabatic collapse of a 15 star by the hydrodynamics
without neutrino transfer, hyperon effects are found to be small, since the
temperature and density do not reach the region of hyperon mixture, where the
hyperon fraction is above 1 % (T > 40 MeV or rho_B > 0.4 fm^{-3}).Comment: 23 pages, 6 figures (Fig.3 and related comments on pion potential are
corrected in v3.
Kaon B parameter from quenched Lattice QCD
We present results of a large-scale simulation for the Kaon B parameter
in quenched lattice QCD with the Kogut-Susskind quark action. Calculating
at 1% statistical accuracy for seven values of lattice spacing in the range
fm on lattices up to , we verify a
quadratic dependence of theoretically predicted. Strong indications
are found that, with our level of accuracy, terms
arising from our one-loop matching procedure have to be included in the
continuum extrapolation. We present (NDR, 2 GeV)=0.628(42) as our final
value, as obtained by a fit including the term.Comment: 8 pages, Latex(revtex, epsf), 2 epsf figure
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