3,656 research outputs found
Anisotropic Lattices and Dynamical Fermions
We report results from full QCD calculations with two flavors of dynamical
staggered fermions on anisotropic lattices. The physical anisotropy as
determined from spatial and temporal masses, their corresponding dispersion
relations, and spatial and temporal Wilson loops is studied as a function of
the bare gauge anisotropy and the bare velocity of light appearing in the Dirac
operator. The anisotropy dependence of staggered fermion flavor symmetry
breaking is also examined. These results will then be applied to the study of
2-flavor QCD thermodynamics.Comment: Lattice2001(spectrum
The D234 action for light quarks
We investigate a new light fermion action (the ``D234'' action), which is
accurate up to \O(a^3) and tadpole-improved \O(a \alpha_s) errors. Using
D234 with Symanzik- and tadpole-improved glue we find evidence that continuum
results for the quenched hadron spectrum (pion, rho and nucleon) can be
obtained on coarse lattices.Comment: Latex, 4 pages, submitted to Lattice '95 proceeding
Charmonia above the Deconfinement Phase Transition
Analyzing correlation functions of charmonia at finite temperature () on
anisotropic lattices by the maximum entropy method (MEM),
we find that and survive as distinct resonances in the plasma
even up to and that they eventually dissociate between and ( is the critical temperature of deconfinement). This
suggests that the deconfined plasma is non-perturbative enough to hold
heavy-quark bound states. The importance of having sufficient number of
temporal data points in the MEM analysis is also emphasized.Comment: Lattice2003(nonzero), 3 pages, 3 figure
Heavy quark action on the anisotropic lattice
We investigate the improved quark action on anisotropic lattice as a
potential framework for the heavy quark, which may enable precision computation
of hadronic matrix elements of heavy-light mesons. The relativity relations of
heavy-light mesons as well as of heavy quarkonium are examined on a quenched
lattice with spatial lattice cutoff 1.6 GeV and the
anisotropy . We find that the bare anisotropy parameter tuned for the
massless quark describes both the heavy-heavy and heavy-light mesons within 2%
accuracy for the quark mass , which covers the charm quark
mass. This bare anisotropy parameter also successfully describes the
heavy-light mesons in the quark mass region within the
same accuracy. Beyond this region, the discretization effects seem to grow
gradually. The anisotropic lattice is expected to extend by a factor the
quark mass region in which the parameters in the action tuned for the massless
limit are applicable for heavy-light systems with well controlled systematic
errors.Comment: 11 pages, REVTeX4, 11 eps figure
Charmed hadron physics in quenched anisotropic lattice QCD
We investigate the anisotropic lattice with improved quark action as a
candidate of framework in which we can treat both the heavy and light quark
region in the same manner and systematically reduce the systematic
uncertainties. To examine applicability of anisotropic lattice, we calculate
the charmed meson spectrum and decay constants in quenched approximation. We
find consistent result with most advanced results on isotropic lattices.Comment: 3 pages, 1 figure, contribution to Fifth KEK Topical Conference -
Frontiers in Flavor Physics -, Tsukuba, Japan, November 20-22, 200
Heavy-light meson in anisotropic lattice QCD
We examine whether the improved quark action on anisotropic lattices
can be used as a framework for the heavy quark, which enables precision
computation of matrix elements of heavy-light mesons. To this end, it is
crucial to verify that a mass independent and nonperturbative tuning of the
parameters is possible. As a first step, we observe the dispersion relation of
heavy-light mesons on a quenched lattice using the action which is
nonperturbatively tuned only for the leading terms. On a lattice with the
spatial cutoff 1.6 GeV and the anisotropy , the
relativity relation holds within 2% accuracy in the quark mass region with the bare anisotropy parameter tuned for the massless quark.
We also apply the action to a calculation of heavy-light decay constants in the
charm quark mass region.Comment: Lattice2002(heavyquark), 3 pages, 2 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
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