BLOCH-NORDSIECK CANCELLATIONS BEYOND LOGARITHMS IN HEAVY-PARTICLE DECAYS

We investigate the one-loop radiative corrections to the semileptonic decay of a charged particle at finite gauge boson mass. Extending the Bloch-Nordsieck cancellation of infrared logarithms, the two subsequent nonanalytic terms are also found to vanish after eliminating the pole mass of the decaying particle in favor of a mass defined at short distances. This observation justifies the operator product expansion for inclusive decays of heavy charged particles and implies that infrared effects are suppressed by at least three powers of the heavy mass. © 1994 The American Physical Society.