Color-Kinematics Duality in Multi-Regge Kinematics and Dimensional Reduction

TL;DR

This paper investigates the application of color-kinematics duality to scattering processes in QCD and gravity, demonstrating that certain theory extensions via dimensional reduction enable correct gravitational amplitude reconstruction in multi-Regge kinematics.

Contribution

It introduces two extensions of gauge theories, via scalar contact interactions and scalar distinguishability relaxation, that enable the double-copy method to reproduce gravitational amplitudes in multi-Regge kinematics.

Findings

Extensions allow full reconstruction of gravitational amplitudes.

Dimensional reduction links gauge theory modifications to gravity.

Correct Regge limit achieved with new diagrams.

Abstract

In this note we study the applicability of the color-kinematics duality to the scattering of two distinguishable scalar matter particles with gluon emission in QCD, or graviton emission in Einstein gravity. Previous analysis suggested that direct use of the Bern-Carrasco-Johansson double-copy prescription to matter amplitudes does not reproduce the gravitational amplitude in multi-Regge kinematics. This situation, however, can be avoided by extensions to the gauge theory, while maintaning the same Regge limit. Here we present two examples of these extensions: the introduction of a scalar contact interaction and the relaxation of the distinguishability of the scalars. In both cases new diagrams allow for a full reconstruction of the correct Regge limit on the gravitational side. Both modifications correspond to theories obtained by dimensional reduction from higher-dimensional gauge theories.