Sub-subleading soft gravitons: New symmetries of quantum gravity?

TL;DR

This paper provides evidence that a third factorization constraint in quantum gravity amplitudes corresponds to new symmetries, suggesting the symmetry group of quantum gravity is larger than the known BMS group.

Contribution

It establishes a link between a third factorization constraint and new symmetries in quantum gravity, expanding the understanding of its symmetry group.

Findings

Third factorization constraint relates to new quantum gravity symmetries

Symmetry group may be larger than BMS group

Supports richer structure of quantum gravity symmetries

Abstract

Due to seminal works of Weinberg, Cachazo and Strominger we know that tree level quantum gravity amplitudes satisfy three factorization constraints. Building on previous works which relate two of these constraints to symmetries of quantum gravity at null infinity, we present rather strong evidence that the third constraint is also equivalent to a new set of symmetries of (perturbative) quantum gravity. Our analysis implies that the symmetry group of quantum gravity may be even richer than the BMS group (or infinite dimensional extension thereof) previously considered.