9,410 research outputs found
SU(3) Latent Heat and Surface Tension from Tree Level and Tadpole Improved Actions
We analyze the latent heat and surface tension at the SU(3) deconfinement
phase transition with tree level and tadpole improved Symanzik actions on
lattices with temporal extent and 4 and spatial extent , 6 and 8. In comparison to the standard Wilson action we do find a
drastic reduction of cut-off effects already with tree level improved actions.
On lattices with temporal extent results for the surface tension and
latent heat obtained with a tree level improved action agree well with those
obtained with a tadpole improved action. A comparison with
calculations, however, shows that results obtained with tadpole action remain
unaffected by cut-off effects even on this coarse lattice, while the tree level
action becomes sensitive to the cut-off. For the surface tension and latent
heat we find and , respectively.Comment: 11 pages, LaTeX2e File, 3 Postscript figure
SU(3) Gauge Theory with Adjoint Fermions
We analyze the finite temperature phase diagram of QCD with fermions in the
adjoint representation. The simulations performed with four dynamical Majorana
fermions, which is equivalent to two Dirac fermions, show that the
deconfinement and chiral phase transitions occur at two distinct temperatures,
. While the deconfinement transition
is first order we find evidence for a continuous chiral transition. We also
present potentials for and both for fundamental and adjoint fermion-antifermion pairs.Comment: LATTICE98(hightemp), 3 pages LaTeX2e, espcrc2 style, 6 eps figure
QCD Thermodynamics with Improved Actions
The thermodynamics of the SU(3) gauge theory has been analyzed with tree
level and tadpole improved Symanzik actions. A comparison with the continuum
extrapolated results for the standard Wilson action shows that improved actions
lead to a drastic reduction of finite cut-off effects already on lattices with
temporal extent . Results for the pressure, the critical temperature,
surface tension and latent heat are presented. First results for the
thermodynamics of four-flavour QCD with an improved staggered action are also
presented. They indicate similarly large improvement factors for bulk
thermodynamics.Comment: Talk presented at LATTICE96(finite temperature) 4 pages, LaTeX2e
file, 6 eps-file
Soil Liquefaction Potential Evaluation with Use of the Simplified Procedure
A simplified method based on both a liquefaction resistance factor, FL and a liquefaction potential factor, PL has been proposed for evaluating soil liquefaction potential. The factor FL indicates the liquefaction potential at a given depth of a site, and the factor PL indicates the one at a site. The effectiveness of the proposed method is investigated by calculating the factors FL and PL at both liquefied and non-liquefied sites during past typical earthquakes in Japan, and carrying out shaking table tests
The three flavour chiral phase transition with an improved quark and gluon action in lattice QCD
The finite-temperature chiral phase transition is investigated for three
flavours of staggered quarks on a lattice of temporal extent N_t=4. In the
simulation we use an improved fermion action which reduces rotational symmetry
breaking of the quark propagator (p4-action), include fat-links to improve the
flavour symmetry and use the tree level improved (1,2) gluon action. We study
the nature of the phase transition for quark masses of ma=0.025, ma=0.05 and
ma=0.1 on lattices with spatial sizes of 8^3 and 16^3.Comment: LATTICE98(hightemp), 3 pages, 7 figures, LaTeX2e-File, espcrc2.st
Improved Actions for QCD Thermodynamics on the Lattice
Finite cut-off effects strongly influence the thermodynamics of lattice
regularized QCD at high temperature in the standard Wilson formulation. We
analyze the reduction of finite cut-off effects in formulations of the
thermodynamics of gauge theories with three different and
improved actions. We calculate the energy density and pressure on
finite lattices in leading order weak coupling perturbation theory
() and perform Monte Carlo simulations with improved
actions at non-zero . Already on lattices with temporal extent
we find a strong reduction of finite cut-off effects in the high
temperature limit, which persists also down to temperatures a few times the
deconfinement transition temperature.Comment: 20 pages, 3 Postscript figure
Testing improved actions for dynamical Kogut-Susskind quarks
We extend tests of "Naik" and "fat link" improvements of the Kogut-Susskind
quark action to full QCD simulations, and verify that the improvements
previously demonstrated in the quenched approximation apply also to dynamical
quark simulations. We extend the study of flavor symmetry improvement to the
complete set of pions, and find that the nonlocal pions are significantly
heavier than the local non-Goldstone pion. These results can be used to
estimate the lattice spacing necessary for realistic simulations with this
action.Comment: 16 pages, LaTeX, PostScript figures include
Finite Temperature Transitions in Lattice QCD with Wilson Quarks --- Chiral Transitions and the Influence of the Strange Quark ---
The nature of finite temperature transitions in lattice QCD with Wilson
quarks is studied near the chiral limit for the cases of 2, 3, and 6 flavors of
degenerate quarks (, 3, and 6) and also for the case of massless up and
down quarks and a light strange quark (). Our simulations mainly
performed on lattices with the temporal direction extension indicate
that the finite temperature transition in the chiral limit (chiral transition)
is continuous for , while it is of first order for and 6. We
find that the transition is of first order for the case of massless up and down
quarks and the physical strange quark where we obtain a value of
consistent with the physical value. We also discuss the phase
structure at zero temperature as well as that at finite temperatures.Comment: uuencoded compressed tar file, 70 pages, 32 figure
Perfect lattice action for asymptotically free theories
There exist lattice actions which give cut--off independent physical
predictions even on coarse grained lattices. Rotation symmetry is restored, the
spectrum becomes exact and, in addition, the classical equations have scale
invariant instanton solutions. This perfect action can be made short ranged. It
can be determined by combining analytical calculations with numerical
simulations on small lattices. We illustrate the method and the benefits on the
non--linear --model.Comment: 29 pages(part 1) + 9 postscript figures(part 2, compressed by
uufiles). No changes, replaced due to transmission error observed, BUTP-93/1
Equation of state for pure SU(3) gauge theory with renormalization group improved action
A lattice study of the equation of state for pure SU(3) gauge theory using a
renormalization-group (RG) improved action is presented. The energy density and
pressure are calculated on a and a lattice
employing the integral method. Extrapolating the results to the continuum
limit, we find the energy density and pressure to be in good agreement with
those obtained with the standard plaquette action within the error of 3-4%.Comment: 17 pages, 14 figures, revte
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