Support of theoretical high energy physics research at the Supercomputer Computations Research Institute]. Final report, September 30, 1992--July 31, 1997

Abstract

The research primarily involved lattice field theory simulations such as Quantum Chromodynamics (QCD) and the Standard Model of electroweak interactions. Among the works completed by the members of the lattice group and their outside collaborators in QCD simulations are extensive hadronic spectrum computations with both Wilson and staggered fermions, and calculations of hadronic matrix elements and wavefunctions. Studies of the QCD {beta} function with two flavors of Wilson fermions, and the study of a possible flavor-parity breaking phase in QCD with two flavors of Wilson fermions have been completed. Studies of the finite temperature behavior of QCD have also been a major activity within the group. Studies of non-relativistic QCD, both for heavy-heavy mesons and for the heavy quark in heavy-light mesons have been done. Combining large N analytic computations within the Higgs sector of the standard model and numerical simulations at N = 4 have yielded a computation of the upper bound of the mass of the Higgs particle, as well as the energy scale above which deviations from the Standard Model may be expected. A major research topic during the second half of the grant period was the study of improved lattice actions, designed to diminish finite lattice spacing effects and thus accelerate the approach to the continuum limit. A new exact Local Hybrid Monte Carlo (overrelaxation) algorithm with a tunable overrelaxation parameter has been developed for pure gauge theories. The characteristics of this algorithm have been investigated. A study of possible instabilities in the global HMC algorithm has been completed.