Next-to-soft corrections to high energy scattering in QCD and gravity

TL;DR

This paper analyzes high energy scattering in QCD and gravity, computing next-to-soft corrections beyond the eikonal approximation for scalar particles, revealing new insights into gluon Reggeization and gravitational deflections.

Contribution

It systematically calculates next-to-soft corrections in high energy scattering in both QCD and gravity, extending previous work to arbitrary scalar masses and confirming conjectures about gravitational deflections.

Findings

Power-suppressed corrections to gluon Reggeization in QCD.

Confirmation that next-to-soft gravity corrections involve two deflection angles.

Consistency with the double copy relation between QCD and gravity amplitudes.

Abstract

We examine the Regge (high energy) limit of 4-point scattering in both QCD and gravity, using recently developed techniques to systematically compute all corrections up to next-to-leading power in the exchanged momentum i.e. beyond the eikonal approximation. We consider the situation of two scalar particles of arbitrary mass, thus generalising previous calculations in the literature. In QCD, our calculation describes power-suppressed corrections to the Reggeisation of the gluon. In gravity, we confirm a previous conjecture that next-to-soft corrections correspond to two independent deflection angles for the incoming particles. Our calculations in QCD and gravity are consistent with the well-known double copy relating amplitudes in the two theories.