U(1) gap equation and consistency condition in quantum chromodynamics

We unify most aspects of the "resolution" of the U(1) problem in QCD-nonperturbative as well as perturbative-by calculating one second-order gluon quark-annihilation or "diamond" diagram. This leads to a U(1) gap equation and consistency condition which is numerically satisfied, providing one exchanges eight color, spin-one, massless gluons, as required in QCD. © 1983 The American Physical Society.