2,827 research outputs found
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
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
Pion decay constant in quenched QCD with Kogut-Susskind quarks
We present a non-perturbative calculation for the pion decay constant with
quenched Kogut-Susskind quarks. Numerical simulations are carried out at and 6.2 with various operators extending over all flavors. The
renormalization correction is applied for each flavor by computing
non-perturbative renormalization constants, and it is compared with a
perturbative calculation. We also study the behavior of in the
continuum limits for both non-perturbative and perturbative calculations. The
results in the continuum limit is also discussed.Comment: LATTICE99(matrix elements) 3 pages, 4 eps figure
Metal-insulator transition caused by the coupling to localized charge-frustrated systems under ice-rule local constraint
We report the results of our theoretical and numerical study on electronic
and transport properties of fermion systems with charge frustration. We
consider an extended Falicov-Kimball model in which itinerant spinless fermions
interact repulsively by U with localized particles whose distribution satisfies
a local constraint under geometrical frustration, the so-called ice rule. We
numerically calculate the density of states, optical conductivity, and inverse
participation ratio for the models on the pyrochlore, checkerboard, and kagome
lattices, and discuss the nature of metal-insulator transitions at commensurate
fillings. As a result, we show that the ice-rule local constraint leads to
several universal features in the electronic structure; a charge gap opens at a
considerably small U compared to the bandwidth, and the energy spectrum
approaches a characteristic form in the large U limit, that is, the
noninteracting tight-binding form in one dimension or the -functional
peak. In the large U region, the itinerant fermions are confined in the
macroscopically-degenerate ice-rule configurations, which consist of a bunch of
one-dimensional loops: We call this insulating state the charge ice. On the
other hand, transport properties are much affected by the geometry and
dimensionality of lattices; e.g., the pyrochlore lattice model exhibits a
transition from a metallic to the charge-ice insulating state by increasing U,
while the checkerboard lattice model appears to show Anderson localization
before opening a gap. Meanwhile, in the kagome lattice case, we do not obtain
clear evidence of Anderson localization. Our results elucidate the universality
and diversity of phase transitions to the charge-ice insulator in fully
frustrated lattices.Comment: 16 pages, 17 figure
Quantum melting of charge ice and non-Fermi-liquid behavior: An exact solution for the extended Falicov-Kimball model in the ice-rule limit
An exact solution is obtained for a model of itinerant electrons coupled to
ice-rule variables on the tetrahedron Husimi cactus, an analogue of the Bethe
lattice of corner-sharing tetrahedra. It reveals a quantum critical point with
the emergence of non-Fermi-liquid behavior in melting of the "charge ice"
insulator. The electronic structure is compared with the numerical results for
the pyrochlore-lattice model to elucidate the physics of electron systems
interacting with the tetrahedron ice rule.Comment: 5 pages, 4 figure
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
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
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