Soft contribution to the damping rate of a hard photon in a weakly magnetized hot medium

TL;DR

This paper calculates the damping rate of a hard photon in a weakly magnetized hot QED plasma, revealing how magnetic fields influence photon attenuation through thermal and magnetic effects.

Contribution

It introduces a formalism to evaluate the soft contribution to the photon damping rate considering thermo-magnetic effects, extendable to QCD plasma.

Findings

Magnetic field reduces the photon damping rate compared to thermal effects.

Separation of thermal and thermo-magnetic contributions in weak field approximation.

Formalism applicable to QCD plasma for similar damping rate calculations.

Abstract

We consider weakly magnetized hot QED plasma comprising electrons and positrons. There are three distinct dispersive (longitudinal and two transverse) modes of a photon in a thermo-magnetic medium. At lowest order in coupling constant, photon is damped in this medium via Compton scattering and pair creation process. We evaluate the damping rate of hard photon by calculating the imaginary part of the each transverse dispersive modes in a thermo-magnetic QED medium. We note that one of the fermions in the loop of one-loop photon self-energy is considered as soft and the other one is hard. Considering the resummed fermion propagator in a weakly magnetized medium for the soft fermion and the Schwinger propagator for hard fermion, we calculate the soft contribution to the damping rate of hard photon. In weak field approximation the thermal and thermo-magnetic contributions to damping rate get separated out for each transverse dispersive mode. The total damping rate for each dispersive mode in presence of magnetic field is found to be reduced than that of the thermal one. This formalism can easily be extended to QCD plasma.