O(N)-Symmetric sigma-Model on Finite Lattice: Perturbation Theory Vs. Resummed 1/N-Expansion

摘要

Dyson-Schwinger equations exact to O(1/N) are solved perturbatively at weak coupling for the two-point function of the O(N)-symmetric non-linear sigma-model on a finite lattice. The solution equals the known second order weak coupling result to all powers in 1/N (third and higher powers have coefficient zero). In the Dyson-Schwinger equations zero momentum modes cause no problems. On the contrary, their dominance is the basis for a simple expansion scheme. (ERA citation 13:057875)