Dynamics of Langevin Simulation

This chapter [of a supplement to Prog. Theo. Phys.] reviews numerical simulations of quantum field theories based on stochastic quantization and the Langevin equation. The topics discussed include renormalization of finite step-size algorithms, Fourier acceleration, and the relation of the Langevin equation to hybrid stochastic algorithms and hybrid Monte Carlo.Comment: 20 p

Non-perturbative Renormalization of Lattice Operators

We briefly review and compare three methods (one perturbative, one based on Ward Identities and one non-perturbative) for the calculation of the renormalization constants of lattice operators. The following results are presented: (a) non perturbative renormalization of the operators with light quarks; (b) the renormalization constants with a heavy (charm) quark mass and its KLM improvement; (c) the non perturbative determination of the mixing of the $\Delta S = 2$ operator.Comment: 9 pages, uuencoded PS file, 8 figures included, 1 tabl

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

Accumulating evidence for nonstandard leptonic decays of D_s mesons

The measured rate for D_s -> l nu decays, where l is a muon or tau, is larger than the standard model prediction, which relies on lattice QCD, at the 3.8 sigma level. We discuss how robust the theoretical prediction is, and we show that the discrepancy with experiment may be explained by a charged Higgs boson or a leptoquark.Comment: 4 pages; v2 conforms with PRL versio

Monopole Spectra in non-Abelian Gauge Theories

We study the continuum limit of the length spectrum of magnetic monopole structures found after various Abelian projections of pure gauge SU(2), including the maximally Abelian gauge. We comment on Gribov copies, and measurements of the string tension.Comment: Talk presented at LATTICE96(topology) LaTeX, with 4 LaTeX figure