Thermal Field Theory in real-time formalism: concepts and applications for particle decays

TL;DR

This paper reviews Thermal Field Theory in real-time formalism, focusing on particle decay processes, and provides thermal decay rates for various reactions, highlighting the significance of thermal effects in high-temperature particle phenomenology.

Contribution

It extends previous work by including chemical potentials and multiple species in decay rate calculations within the real-time formalism of TFT.

Findings

Thermal decay rates differ significantly from zero-temperature results.

Inclusion of chemical potentials affects decay processes.

Thermal effects are crucial in high-temperature and high-density systems.

Abstract

This review represents a detailed and comprehensive discussion of the Thermal Field Theory (TFT) concepts and key results in Yukawa-type theories. We start with a general pedagogical introduction into the TFT in the imaginary- and real-time formulation. As phenomenologically relevant implications, we present a compendium of thermal decay rates for several typical reactions calculated within the framework of the real-time formalism and compared to the imaginary-time results found in the literature. Processes considered here are those of a neutral (pseudo)scalar decaying into two distinct (pseudo)scalars or into a fermion-antifermion pair. These processes are extended from earlier works to include chemical potentials and distinct species in the final state. In addition, a (pseudo)scalar emission off a fermion line is also discussed. These results demonstrate the importance of thermal effects in particle decay observables relevant in many phenomenological applications in systems at high temperatures and densities.