Creutz Ratios From Color-Truncated Lattice Configurations

We investigate whether information about Creutz ratios is encoded, separately, in each gluon color component of numerically generated lattice configurations. Working in SU(2) lattice gauge theory in Landau gauge, we set two of the three gluon color components to zero, and compensate for the loss of two-thirds of the fluctuation by simply rescaling the remaining component by a factor of $\sqrt{3}$. Creutz ratios are then computed with this "abelianized" configuration. We find that the Creutz ratios of loops constructed from abelianized links converge to the usual Creutz ratios in the scaling regime.Comment: 5 pages, plain LaTeX, one figur

Dual Superconductor Mechanism of Confinement on the Lattice

We investigate the dual superconductor mechanism of confinement for pure SU(2) lattice gauge theory in the maximally abelian gauge. We focus on the the dual Meissner effect. We find that the transverse distribution of the longitudinal chromoelectric field due to a static quark-antiquark pair satisfies the dual London equation. Moreover we show that the size of the flux tube scales according to asymptotic freedom.Comment: LaTeX, 9 pages, 6 figures available as a PostScript file from L. Cosmai, BARI - TH 110/9

Large Dual Transformations and the Petrov-Diakonov Representation of the Wilson Loop

In this work, based on the Petrov-Diakonov representation of the Wilson loop average W in the SU(2) Yang-Mills theory, together with the Cho-Fadeev-Niemi decomposition, we present a natural framework to discuss possible ideas underlying confinement and ensembles of defects in the continuum. In this language we show how for different ensembles the surface appearing in the Wess-Zumino term in W can be either decoupled or turned into a variable, to be summed together with gauge fields, defects and dual fields. This is discussed in terms of the regularity properties imposed by the ensembles on the dual fields, thus precluding or enabling the possibility of performing the large dual transformations that would be necessary to decouple the initial surface.Comment: 35 pages, LaTeX, corrected version, accepted for publication in Phys. Rev.

Systematic study of autocorrelation time in pure SU(3) lattice gauge theory

Results of our autocorrelation measurement performed on Fujitsu AP1000 are reported. We analyze (i) typical autocorrelation time, (ii) optimal mixing ratio between overrelaxation and pseudo-heatbath and (iii) critical behavior of autocorrelation time around cross-over region with high statistic in wide range of $\beta$ for pure SU(3) lattice gauge theory on $8^4$, $16^4$ and $32^4$ lattices. For the mixing ratio K, small value (3-7) looks optimal in the confined region, and reduces the integrated autocorrelation time by a factor 2-4 compared to the pseudo-heatbath. On the other hand in the deconfined phase, correlation times are short, and overrelaxation does not seem to matter For a fixed value of K(=9 in this paper), the dynamical exponent of overrelaxation is consistent with 2 Autocorrelation measurement of the topological charge on $32^3 \times 64$ lattice at $\beta$ = 6.0 is also briefly mentioned.Comment: 3 pages of A4 format including 7-figure

Effects of Chemical Potential on Hadron Masses at Finite Temperature

We study the effects of the chemical potential on the $\rho$ meson mass at finite temperature. Our preliminary results show that some effects are seen in the vicinity of the phase transition point. Although the signal is still too noisy to obtain conclusive physical results within limited statistics, the mass susceptibility is consistent with zero.Comment: LATTICE98(hightemp), 3 page

Evidence of Strong Correlation between Instanton and QCD-monopole on SU(2) Lattice

The correlation between instantons and QCD-monopoles is studied both in the lattice gauge theory and in the continuum theory. An analytical study in the Polyakov-like gauge, where $A_4(x)$ is diagonalized, shows that the QCD-monopole trajectory penetrates the center of each instanton, and becomes complicated in the multi-instanton system. Using the SU(2) lattice with $16^4$, the instanton number is measured in the singular (monopole-dominating) and regular (photon-dominating) parts, respectively. The monopole dominance for the topological charge is found both in the maximally abelian gauge and in the Polyakov gauge.Comment: 4 pages, Latex, 3 figures. Talk presented by H. Suganuma at International Symposium on 'Lattice Field Theory', July 11 - 15, 1995, Melbourne, Australi

Autocorrelation in Updating Pure SU(3) Lattice Gauge Theory by the use of Overrelaxed Algorithms

We measure the sweep-to-sweep autocorrelations of blocked loops below and above the deconfinement transition for SU(3) on a $16^4$ lattice using 20000-140000 Monte-Carlo updating sweeps. A divergence of the autocorrelation time toward the critical $\beta$ is seen at high blocking levels. The peak is near $\beta$ = 6.33 where we observe 440 $\pm$ 210 for the autocorrelation time of $1\times 1$ Wilson loop on $2^4$ blocked lattice. The mixing of 7 Brown-Woch overrelaxation steps followed by one pseudo-heat-bath step appears optimal to reduce the autocorrelation time below the critical $\beta$. Above the critical $\beta$, however, no clear difference between these two algorithms can be seen and the system decorrelates rather fast.Comment: 4 pages of A4 format including 6-figure

Incorporation of QCD Effects in Basic Corrections of the Electroweak Theory

We study the incorporation of QCD effects in the basic electroweak corrections \drcar, \drcarw, and \dr. They include perturbative \Ord{\alpha\alpha_s} contributions and $t\bar{t}$ threshold effects. The latter are studied in the resonance and Green-function approaches, in the framework of dispersion relations that automatically satisfy relevant Ward identities. Refinements in the treatment of the electroweak corrections, in both the \ms\ and the on-shell schemes of renormalization, are introduced, including the decoupling of the top quark in certain amplitudes, its effect on \hat{e}^2(\mz) and \sincarmz, the incorporation of recent results on the leading irreducible \Ord{\alpha^2} corrections, and simple expressions for the residual, i.e.\ ``non-electromagnetic'', parts of \drcar, \drcarw, and \dr. The results are used to obtain accurate values for \mw\ and \sincarmz, as functions of \mt\ and \mh. The higher-order effects induce shifts in these parameters comparable to the expected experimental accuracy, and they increase the prediction for \mt\ derived from current measurements. The \ms\ and the on-shell calculations of \dr, in a recently proposed formulation, are compared and found to be in excellent agreement over the wide ranges 60\GeV \leq \mh \leq 1 \TeV, \mz \leq \mt \leq 250 \GeV.Comment: 51 pages (needs doublespace, equations, and cite styles