Resummed Effective Action in Inhomogeneous External Field at Zero and Finite Temperature

TL;DR

This paper discusses methods for resumming the effective action of massless and nearly massless particles in inhomogeneous external fields at zero and finite temperatures, ensuring infrared finiteness.

Contribution

It introduces resummation techniques for the effective action in inhomogeneous fields applicable at both zero and finite temperatures, including the case of small but finite mass.

Findings

Infrared finite effective action for massless particles in inhomogeneous fields

Extension of resummation methods to finite temperature scenarios

Brief analysis of small-mass particle effects

Abstract

The two ways of resumming the efffective action for the massless test particles in inhomogeneous external field at zero and finite temperature providing the infrared finite answer are discussed. The case of the massive test particles having a mass which is parametrically small with respect to a scale set by the inhomogeneous external field is briefly considered.