Asymptotic charges as detectors and the memory effect in massive QED and perturbative quantum gravity

TL;DR

This paper rederives asymptotic symmetries in quantum gravity and QED using detectors, clarifies their relation to memory effects, and extends results to include external hard gravitons with corrected discrepancies.

Contribution

It introduces a detector-based approach to asymptotic symmetries, including full time dependence in dressings, to better understand memory effects and external gravitons.

Findings

Faddeev-Kulish dressings encode the memory effect in scattering states.

Detectors clarify and extend asymptotic symmetry results.

Physical contributions to memory eigenvalues are identified from dressings.

Abstract

It has been shown that there are an infinite set of asymptotic symmetries in quantum gravity and QED, and this has been extended to dressed states in some cases. Here we rederive these statements in terms of detectors in order to clarify, confirm, and generalize these results to include external hard gravitons. Using detectors and including the full t dependence in Faddeev-Kulish dressings allows us to correct discrepancies in the literature and make new statements. We show that Faddeev-Kulish dressings correctly encode the memory effect in the 'in' and 'out' scattering Fock spaces. We find a physical contribution to the memory eigenvalues arising from the dressings in both cases.