English

Collinear Corrections to the Cachazo-Strominger Soft Theorem

High Energy Physics - Theory 2025-04-24 v1

Abstract

Soft theorems describe the behavior of scattering amplitudes when one or several external particles are taken to be energetically soft. In tree-level gravity there are universal soft theorems for the three leading orders in the soft expansion, and they can be shown to be equivalent to Ward identities of asymptotic symmetries. While the leading and subleading symmetries are understood as supertranslations and superrotations respectively, the precise symmetry interpretation of the sub-subleading soft theorem is still a matter of investigation. The form of the sub-subleading soft graviton theorem was elucidated by Cachazo and Strominger using a BCFW expansion of graviton amplitudes. In this work we show that consistency with results based on asymptotic charges requires a careful treatment of collinear singularities in the amplitude, giving rise to collinear corrections to the usual Cachazo-Strominger soft theorem.

Keywords

Cite

@article{arxiv.2504.16903,
  title  = {Collinear Corrections to the Cachazo-Strominger Soft Theorem},
  author = {Eivind Jørstad and Sruthi A. Narayanan},
  journal= {arXiv preprint arXiv:2504.16903},
  year   = {2025}
}

Comments

14 pages, 4 appendices

R2 v1 2026-06-28T23:08:50.747Z