EVALUATION OF THERMAL CORRECTIONS TO FALSE VACUUM DECAY-RATES

We examine the computation of the nucleation barrier used in the expre ssion for false vacuum decay rates in finite-temperature field theory. By a detailed analysis of the determinantal prefactor, we show that t he correct bounce solution used in the computation of the nucleation b arrier should not include loop corrections coming from the scalar fiel d undergoing decay. Temperature corrections to the bounce appear from loop contributions from other fields coupled to the scalar field. We c ompute the nucleation barrier for a model of scalar fields coupled to fermions, and compare our results to the expression commonly used in t he literature. We find that, for large enough self-couplings, the incl usion of scalar loops in the expression of the nucleation barrier lead s to an underestimate of the decay rate in the neighborhood of the cri tical temperature.