Charged-Particle Decay at Finite Temperature

TL;DR

This paper calculates how a thermal photon bath affects charged fermion decay rates at temperatures below particle masses, addressing infrared divergences and exploring implications for early Universe physics.

Contribution

It provides the first detailed calculation of finite-temperature radiative corrections to charged fermion decays, including divergence cancellation and potential cosmological implications.

Findings

Finite-temperature infrared divergences are canceled in decay rates.

Temperature-dependent corrections are quantified for hypothetical and electroweak decays.

Implications for charged particles in the early Universe are discussed.

Abstract

Radiative corrections to the decay rate of charged fermions caused by the presence of a thermal bath of photons are calculated in the limit when temperatures are below the masses of all charged particles involved. The cancellation of finite-temperature infrared divergences in the decay rate is described in detail. Temperature-dependent radiative corrections to a two-body decay of a hypothetical charged fermion and to electroweak decays of a muon are given. We touch upon possible implications of these results for charged particles in the early Universe.