Soft Photon theorem in the small negative cosmological constant limit

TL;DR

This paper investigates how electromagnetic interactions modify classical soft theorems in asymptotically AdS spacetimes with a small cosmological constant, deriving leading order corrections to soft factors and associated Ward identities.

Contribution

It introduces the first perturbative corrections to soft theorems in asymptotically AdS backgrounds, extending the known flat spacetime results to include small cosmological constant effects.

Findings

Derived $1/l^2$ corrections to soft factors in AdS

Established a corrected Ward identity incorporating the cosmological constant

Confirmed the universality of the leading soft factor beyond tree level

Abstract

We study the effect of electromagnetic interactions on the classical soft theorems on an asymptotically AdS background in 4 spacetime dimensions, in the limit of a small cosmological constant or equivalently a large AdS radius $l$. This identifies $1/l^2$ perturbative corrections to the known asymptotically flat spacetime leading and subleading soft factors. Our analysis is only valid to leading order in $1/l^2$. The leading soft factor can be expected to be universal and holds beyond tree level. This allows us to derive a $1/l^2$ corrected Ward identity, following the known equivalence between large gauge Ward identities and soft theorems in asymptotically flat spacetimes.