Color-Kinematics Duality and the Regge Limit of Inelastic Amplitudes

TL;DR

This paper explores the color-kinematics duality in scalar-QCD and gravitational amplitudes, demonstrating universality in the multi-Regge limit and confirming the double copy correspondence for reggeized particles.

Contribution

It provides a detailed analysis of five-point amplitudes in scalar-QCD and their gravitational counterparts, highlighting the universality of certain couplings in the Regge limit via the duality.

Findings

Universal coupling of reggeized gravitons to on-shell gravitons confirmed

Double copy construction reproduces key gravitational amplitude features

Multi-Regge limit behavior aligns with theoretical expectations

Abstract

We investigate tree-level five-point amplitudes in scalar-QCD expressed in terms of Sudakov variables and find the equivalent "gravitational" counterparts using the color-kinematics duality proposed by Bern, Carrasco, and Johannson. Taking the multi-Regge limit in the gravitational amplitudes, we show that those pieces in the coupling of two reggeized gravitons to one on-shell graviton directly stemming from the double copy of the vertex for two reggeized gluons to one on-shell gluon are universal and properly reproduced by the duality.