Apparently noninvariant terms of $U(N)\times U(N)$ nonlinear sigma model in the one-loop approximation

Abstract

We show how the Apparently Noninvariant Terms (ANTs), which emerge in perturbation theory of nonlinear sigma models, are consistent with the nonlinearly realized symmetry by employing the Ward-Takahashi identity (in the form of an inhomogeneous Zinn-Justin equation). In the literature the discussions on ANTs are confined to the SU(2) case. We generalize them to the U(N) case and demonstrate explicitly at the one-loop level that despite the presence of divergent ANTs in the effective action of the "pions", the symmetry is preserved.

two paragraphs added in Introduction, typos in Eqs. fixed

References in corpus (1)

• Further Comments on the Symmetric Subtraction of the Nonlinear Sigma Model

Cited by in corpus (1)

• Pions are neither perturbative nor nonperturbative: Wilsonian renormalization group analysis of nuclear effective field theory including pions