Non-perturbative Renormalization Group Approach to Dynamical Chiral Symmetry Breaking in Gauge Theories

Abstract

We analyze the dynamical chiral symmetry breaking in gauge theories solely by the non-perturbative renormalization group, without recourse to the Schwinger-Dyson method. First, we briefly review the basic notions and formulation, and clarify its great feature that it gives a systematic approximation scheme without any divergent series nor serious gauge dependence, compared to other perturbative and non-perturbative methods. Then we apply this new method to QED and QCD to find that our lowest level approximation improves the ladder Schwinger-Dyson equation results in a gauge independent way. We get the chiral phase structures and the critical exponents in the fixed gauge coupling analysis, and also calculate the chiral condensates in case of running QCD.