The Charmonium Spectrum on the Lattice: A Status Report

We present our most recent results on the charmonium spectrum using relativistic Wilson fermions. We study the dependence of the spectrum on the charm quark mass and the Wohlert-Sheikholeslami improvement term.Comment: 4 pages, LaTeX, 5 figures (eps), needs espcrc2.sty, epsf.sty. FERMILAB-CONF-92/330-

Standard Model Parameters from Quarkonia using Lattice QCD

Quarkonia -- mesons made of a heavy quark and anti-quark -- have been extensively studied experimentally. Theoretical calculations of quarkonia based on lattice QCD are possible with control over the systematic errors. The comparison with experimental measurements of the quarkonia spectra leads to determinations of Standard Model parameters: the strong coupling, $\alpha_s$, and the heavy quark masses.Comment: 14 pages uuencoded postscript; To appear in the proceedings of PASCOS'95, Baltimore, MD, March 22-25, 1995

A Study of PCAC for the Nonperturbative Improvement of the Wilson Action

We present an exploratory study for the nonperturbative determination of the coefficient of the ${\cal O}(a)$ improvement term to the Wilson action, $c_{SW}$. Following the work by L\"{u}scher et al., we impose the PCAC relation as a nonperturbative improvement condition on $c_{SW}$, without, however, using the Schr\"{o}dinger functional in our calculation.Comment: 3 pages, LaTeX (uses espcrc2.sty), 4 postscript figures, to be published in the proceedings of Lattice'9

Vacuum Decay and Euclidean Lattice Monte Carlo

The decay rate of a metastable vacuum is usually calculated using a semiclassical approximation to the Euclidean path integral. The extension to a complete Euclidean lattice Monte Carlo computation, however, is hampered by analytic continuations that are ill-suited to numerical treatment, and the nonequilibrium nature of a metastable state. In this paper we develop a new methodology to compute vacuum decay rates from Monte Carlo simulations of Euclidean lattice theories. To test the new method, we consider simple quantum mechanical systems systems with metastable vacua. This work can be extended to Euclidean field theories, which we discuss in the Conclusions.Comment: 33 pages, 10 figure