2-DIMENSIONAL SU(N)-X-SU(N) CHIRAL MODELS ON THE LATTICE

Lattice SU(N)xSU(N) chiral models are analyzed by strong and weak coupling expansions and by numerical simulations. Twelfth-order strong coupling series for the free and internal energy are obtained for all N greater than or equal to 6. Three-loop contributions to the internal energy and to the lattice beta function are evaluated for all N and nonuniversal corrections to the asymptotic ii parameter are computed in the ''temperature'' and the ''energy'' schemes. Numerical simulations confirm a faster approach to asymptopia of the energy scheme. A phenomenological correlation between the peak in the specific heat and the dip of the beta function is observed. Tests of scaling ape performed for various physical quantities, finding substantial scaling at xi greater than or similar to 2. In particular, at N = 6 three different mass ratios are determined numerically and found in agreement, within statistical errors af about 1%, with the theoretical predictions from the exact S-matrix theory.