RADIATIVE-CORRECTIONS TO W AND QUARK PROPAGATORS IN THE RESONANCE REGION

It is shown that conventional mass renormalization, when applied to ph otonic or gluonic corrections to unstable particle propagators, leads to non-convergent series in the resonance region. A solution of this p roblem, based on the concepts of pole mass and width, is presented. In contrast with the Z case, the conventional on-shell definition of mas s for W bosons and unstable quarks contains an unbounded gauge depende nce in next-to-leading order. The on-shell and pole definitions of wid th ale shown to coincide if terms of O(Gamma(2)) and higher are neglec ted, but not otherwise.