A functional approach to soft graviton scattering and BMS charges

TL;DR

This paper develops a functional eikonal approach to analyze soft graviton scattering, incorporating BMS charges to understand infrared effects and information loss during gravitational interactions.

Contribution

It introduces a composite generating functional and a decoherence functional framework to handle infrared divergences and connect scattering with BMS symmetries.

Findings

Formulation of a diffeomorphism-invariant scattering approach

Expression of the decoherence functional in terms of BMS charges

Insights into information loss in gravitational scattering

Abstract

We consider the interaction between a matter system and soft gravitons. We use a functional eikonal expansion to deal with the infrared divergences, and introduce a "composite generating functional" which allows us to calculate a decoherence functional for the time evolution of the system. These techniques allow us to formulate scattering problems in a way which deals consistently with infrared effects, as well as being manifestly diffeomorphism invariant. We show how the asymptotic form of the decoherence functional can be written in terms of the infinitely many conserved charges associated with asymptotic BMS symmetries, and allow us to address the question of how much information is lost during the scattering.