Infrared singularities of QCD scattering amplitudes in the Regge limit to all orders

TL;DR

This paper analyzes the infrared divergences in QCD scattering amplitudes in the high-energy Regge limit, deriving a closed-form expression for the soft anomalous dimension to all orders.

Contribution

It provides a novel all-orders expression for the infrared-singular part of QCD amplitudes in the Regge limit, connecting infrared divergences with high-energy resummation techniques.

Findings

Derived a closed-form for the infrared-singular part of amplitudes.

Predicted the Regge limit of the soft anomalous dimension at any loop order.

Resummed two-Reggeon contributions to next-to-leading-logarithm accuracy.

Abstract

Scattering amplitudes of partons in QCD contain infrared divergences which can be resummed to all orders in terms of an anomalous dimension. Independently, in the limit of high-energy forward scattering, large logarithms of the energy can be resummed using Balitsky-Fadin-Kuraev-Lipatov theory. We use the latter to analyze the infrared-singular part of amplitudes to all orders in perturbation theory and to next-to-leading-logarithm accuracy in the high-energy limit, resumming the two-Reggeon contribution. Remarkably, we find a closed form for the infrared-singular part, predicting the Regge limit of the soft anomalous dimension to any loop order.