Soft Theorems and Memory Effects at Finite Temperatures

TL;DR

This paper investigates how soft theorems and memory effects for photons and gravitons are affected by finite temperatures, revealing temperature-dependent universality and spin sensitivity in scattering processes.

Contribution

It introduces a thermofield dynamics approach to analyze soft theorems at finite temperatures and connects thermal effects to electromagnetic and gravitational memory phenomena.

Findings

Soft factors depend on particle spin at finite temperatures.

Universal behavior emerges at low temperatures.

Thermal contributions to memory effects are consistent with soft factors.

Abstract

We study the soft theorems for photons and gravitons at finite temperatures using the thermofield dynamics approach. The soft factors lose universality at finite temperatures as the soft amplitudes depend on the nature (or spin) of the particles participating in the scattering processes. However, at low temperatures, a universal behaviour is observed in the cross-section of the soft processes. Further, we obtain the thermal contribution to the electromagnetic and gravitational memory effects and show that they are related to the soft factors consistently. The expected zero temperature results are obtained from the soft factors and memories. The thermal effects in soft theorems and memories seem to be sensitive to the spin of the particles involved in scattering.