Soft-collinear gravity beyond the leading power

TL;DR

This paper develops an effective field theory for soft and collinear gravitons interacting with matter, revealing gauge symmetries and structures similar to those in QCD, applicable to all orders in the power expansion.

Contribution

It constructs the first all-orders soft-collinear gravity effective theory, uncovering emergent gauge symmetries and invariant structures analogous to QCD.

Findings

Reveals an emergent soft background gauge symmetry in gravity

Provides a gauge-invariant formulation using soft covariant derivatives and Riemann tensor

Establishes a consistent all-orders power expansion in soft-collinear gravity

Abstract

We construct "soft-collinear gravity", the effective field theory which describes the interaction of collinear and soft gravitons with matter (and themselves), to all orders in the soft-collinear power expansion. Despite the absence of collinear divergences in gravity at leading power, the construction exhibits remarkable similarities with soft-collinear effective theory of QCD (gauge fields). It reveals an emergent soft background gauge symmetry, which allows for a manifestly gauge-invariant representation of the interactions in terms of a soft covariant derivative, the soft Riemann tensor, and a covariant generalisation of the collinear light-cone gauge metric field. The gauge symmetries control both the unsuppressed collinear field components and the inherent inhomogeneity in $\lambda$ of the invariant objects to all orders, resulting in a consistent expansion.