Chiral-symmetry breaking in QCD. I. The infrared domain

Abstract

The Dyson-Schwinger equation for the quark propagator is handled in the infrared in three ways: (i) by a sharp cutoff; (ii) by an automatic infrared cutoff, which yields a pseudolinear equation; (iii) by considering the full nonlinearity. The last treatment is rendered possible by detailed comparison with the pseudolinear case; and it is found that chiral symmetry can be dynamically broken if the effective coupling is strong enough.