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 $N_\tau = 3$ and 4 and spatial extent $N_\sigma/ N_\tau = 4$, 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 $N_\tau=4$ 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 $N_\tau=3$ 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 $\sigma_I/ T_c^3 = 0.0155~(16)$ and $\Delta\epsilon/T_c^4 = 1.40~(9)$, 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, $T_{\rm chiral} \simeq 6.65 T_{\rm deconf}$. While the deconfinement transition is first order we find evidence for a continuous chiral transition. We also present potentials for $T<T_{\rm deconf}$ and $T_{\rm deconf}<T< T_{\rm chiral}$ 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 $N_\tau=4$. 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 $SU(N)$ gauge theories with three different $O(a^2)$ and $O(a^4)$ improved actions. We calculate the energy density and pressure on finite lattices in leading order weak coupling perturbation theory ($T\rightarrow \infty$) and perform Monte Carlo simulations with improved $SU(3)$ actions at non-zero $g^2$. Already on lattices with temporal extent $N_\tau=4$ 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 ($N_F=2$, 3, and 6) and also for the case of massless up and down quarks and a light strange quark ($N_F=2+1$). Our simulations mainly performed on lattices with the temporal direction extension $N_t=4$ indicate that the finite temperature transition in the chiral limit (chiral transition) is continuous for $N_F=2$, while it is of first order for $N_F=3$ 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 $m_\phi/m_\rho$ 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 $d=2$ non--linear $\sigma$--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 $16^3\times 4$ and a $32^3\times 8$ 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