Soft-Collinear Gravity and Soft Theorems
Abstract
This chapter reviews the construction of ``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, focusing on the essential concepts. Among them are an emergent soft background gauge symmetry, which lives on the light-like trajectories of energetic particles and allows for a manifestly gauge-invariant representation of the interactions in terms of a soft covariant derivative and the soft Riemann tensor, and a systematic treatment of collinear interactions, which are absent at leading power in gravity. The gravitational soft theorems are derived from soft-collinear gravity at the Lagrangian level. The symmetries of the effective theory provide a transparent explanation of why soft graviton emission is universal to sub-sub-leading power, but gauge boson emission is not and suggest a physical interpretation of the form of the universal soft factors in terms of the charges corresponding to the soft symmetries. The power counting of soft-collinear gravity further provides an understanding of the structure of loop corrections to the soft theorems.
Cite
@article{arxiv.2210.09336,
title = {Soft-Collinear Gravity and Soft Theorems},
author = {Martin Beneke and Patrick Hager and Robert Szafron},
journal= {arXiv preprint arXiv:2210.09336},
year = {2022}
}
Comments
52 pages, 10 figures; Invited chapter for the Section "Effective Quantum Gravity" edited by C. Burgess and J. Donoghue of the "Handbook of Quantum Gravity" (Eds. C. Bambi, L. Modesto and I.L. Shapiro, Springer Singapore, expected in 2023)