Infrared singularities in multi-leg scattering amplitudes

TL;DR

This paper reviews the current understanding of infrared singularities in multi-leg scattering amplitudes and reports progress on calculating the three-loop soft anomalous dimension using Wilson line correlators.

Contribution

It introduces a new calculation of the three-loop soft anomalous dimension and discusses the generalization of the non-Abelian exponentiation theorem to multiple Wilson lines.

Findings

Progress in calculating the three-loop soft anomalous dimension.

Demonstration of the non-Abelian exponentiation theorem for multiple Wilson lines.

Analysis of the analytic structure of multiple-gluon-exchange webs.

Abstract

I discuss the state-of-the-art knowledge of long-distance singularities in multi-leg gauge-theory scattering amplitudes and report on an on-going calculation of the three-loop soft anomalous dimension through the renormalization of correlators of semi-infinite Wilson lines. I also discuss the non-Abelian exponentiation theorem that has been recently generalised to multiple Wilson lines and demonstrate its application in computing the soft anomalous dimension. Finally, I present recent results for multiple-gluon-exchange webs and discuss their analytic structure.