Ralph Roskies

Monte Carlo study of long-range chiral structure in QCD

Abstract Results of a Monte Carlo study of long-range chiral structure is massless 4-dimensional QCD are presented. The algorithm employed integrates fermion degrees of freedom exactly. The behavior of chiral correlations in both abelian and SU(2) color theories is compared. We find strong evidence for chiral breakdown, with a solution of the U(1) problem, in lattice QCD at large β.

Absence of phase transition in QCD with massless quarks

Abstract SU(3) lattice gauge theory with four flavors of massless Susskind fermions is studied on a small (4 4 ) lattice. The fermion determinant is treated in an exact manner. It is observed that the phase transtion which is seen in the pure gauge theory on that lattice disappears when the fermionic determinant is included in the action.

High-temperature expansions to fifteenth order

High-temperature series expansions of the susceptibility and second moment to 15th order are calculated for zero external field on the linear chain (LC), plane square (PSQ), simple cubic (SC), and body-centered cubic (BCC) lattices. Checks for specific models against pertinent work in the literature are detailed.

Representations of unusual mathematical structures in scientific applications of symbolic computation

We present some techniques we have used to apply REDUCE to problems which have mathematical structures unknown to REDUCE. Our examples, the spectrum of the @a model and the Gross-Neveu model, come from particle physics. We had to handle three-vectors, summation with indefinite upper limit, formatting requirements for producing efficient FORTRAN code, and anti-commuting operators.

The Fermion Determinant in Massless Two-Dimensional QCD

I was very lucky to have been a colleague of Feza Gursey’s from 1965 to 1971 at Yale. As a young Ph. D. I learned a great deal from him—about field theory, group theory, and mathematics in general—and I came to admire his originality and the elegance of his ideas. Most people seem to associate Feza’s physics with aspects of group theory. But what struck me most about him in the late 60’s was his conviction that field theory would be the source of our new insights, even into strong interaction physics. This was by no means the party line at the time.

Remarks on lattice copying

Abstract It is pointed out that the procedure of copying gauge-configurations on a small lattice onto a larger one introduces systematic distortions of the spectrum in lattice gauge theories. The phenomenon is illustrated by explicit calculations in the Schwinger model. The effect of Pade analyses of the hopping parameter expansion is also examined and found to be severe.

Renormalizing the Strong-Coupling Expansion for Quantum Field Theory: Present Status

In this talk we review the progress we have made in determining the renormalized strong coupling expansion in quantum field theory. We restrict ourselves here to λϕ4 field theory in d-dimensions. Our starting point is the lattice version of the path integral representation for the Green’s functions.