Asymptotic safety and the gauged SU(N) nonlinear sigma-model

Abstract

We study the beta functions of the leading, two-derivative terms of the left-gauged SU(N) nonlinear sigma-model in d dimensions. In d>2, we find the usual Gaussian ultraviolet fixed point for the gauge coupling and an attractive non-Gaussian fixed point for the Goldstone boson coupling. The position of the latter fixed point controls the chiral expansion, unitarity and the strength of the tree-level Goldstone boson scattering amplitudes. Attention is paid to the gauge- and scheme-dependence of the results.

Comments: REVTeX4, 11 pages, no figures, v2. Revised version accepted for publication in PRD where comments on large N have been removed