Chiral Expansion from Renormalization Group Flow Equations

We explore the influence of the current quark mass on observables in the low energy regime of hadronic interactions within a renormalization group analysis of the Nambu-Jona-Lasinio model in its bosonized form. We derive current quark mass expansions for the pion decay constant and the pion mass, and we recover analytically the universal logarithmic dependence. A numerical solution of the renormalization group flow equations enables us to determine effective low energy constants from the model. We find values consistent with the phenomenological estimates used in chiral perturbation theory.