Renormalization group analysis of lattice theories and improved lattice action: Two-dimensional non-linear O(N) sigma model

Abstract

A block-spin renormalization group analysis is made for the two-dimensional nonlinear O(N) sigma model. The correlation function on the renormalized trajectory for a renormalization group transformation is explicitly obtained near the non-trivial fixed point by perturbation theory. An improved action is obtained in such a way that it is closest to the renormalized trajectory.