Perturbative soft photon theorems in de Sitter spacetime

TL;DR

This paper investigates how soft photon theorems, which describe low-energy photon behavior, are modified in de Sitter spacetime, revealing universal corrections in the large curvature limit and connecting quantum results with classical electromagnetic memory effects.

Contribution

It derives leading and subleading corrections to flat space soft photon theorems in de Sitter spacetime for generic dimensions, extending the understanding of infrared behavior in curved backgrounds.

Findings

Leading and subleading corrections to soft photon theorems in de Sitter space.

Universality of the corrections in the large curvature limit.

Comparison with classical electromagnetic memory tails in four dimensions.

Abstract

We define a perturbative S-matrix in a local patch of de Sitter background in the limit when the curvature length scale ($\ell$) is large and study the 'soft' behavior of the scalar QED amplitudes in de Sitter spacetime in generic dimensions. We obtain the leading and subleading perturbative corrections to flat space soft photon theorems in the large $\ell$ limit, and comment on the universality of these corrections. We compare our results with the electromagnetic memory tails obtained earlier in $d=4$ using classical radiation analysis.