Bifurcation of the quark self-energy: Infrared and ultraviolet cutoffs

Abstract

The quark self-energy in massless QCD is studied in the approximation that both the quark-gluon vertex and the gluon propagator remain bare. It is shown that chiral invariance is not spontaneously broken at a critical coupling ${\ensuremath{\lambda}}_{c}$>0, unless both infrared and ultraviolet cutoffs are introduced.