Asymptotic symmetries of gravity and soft theorems for massive particles

TL;DR

This paper extends the connection between asymptotic symmetries and soft theorems to include massive particles, showing that generalized BMS symmetries relate to soft graviton theorems for massive scalars.

Contribution

It generalizes the equivalence between BMS Ward identities and soft theorems to massive scalar particles, expanding the scope of asymptotic symmetry analysis in gravity.

Findings

Ward identities for massive scalars are equivalent to soft graviton theorems.

Extended BMS group acts on massive scattering data.

Connection between asymptotic symmetries and soft theorems is confirmed for massive particles.

Abstract

The existing equivalence between (generalized) BMS Ward identities with leading and subleading soft graviton theorems is extended to the case where the scattering particles are massive scalars. By extending the action of generalized BMS group off null infinity at late times, we show that there is a natural action of such group not only on the radiative data at null infinity but also on the scattering data of the massive scalar field. This leads to a formulation of Ward identities associated to the generalized BMS group when the scattering states are massive scalars or massless gravitons and we show that these Ward identities are equivalent to the leading and subleading soft graviton theorems.