Infrared Singularities and Soft Gluon Resummation with Massive Partons

TL;DR

This paper presents a two-loop calculation of the anomalous dimension matrix in QCD, enabling precise soft gluon resummation for processes involving both massless and massive partons, such as top quark pair production.

Contribution

It provides the first analytical two-loop anomalous dimension matrix for mixed massless and massive partons, advancing soft gluon resummation techniques in QCD.

Findings

Calculated infrared poles for top quark pair production processes.

Enabled next-to-next-to-leading-logarithmic resummation for complex scattering amplitudes.

Enhanced understanding of infrared singularities in QCD with massive partons.

Abstract

Infrared divergences of QCD scattering amplitudes can be derived from an anomalous dimension matrix, which is also an essential ingredient for the resummation of large logarithms due to soft gluon emissions. We report a recent analytical calculation of the anomalous dimension matrix with both massless and massive partons at two-loop level, which describes the two-loop infrared singularities of any scattering amplitudes with an arbitrary number of massless and massive partons, and also enables soft gluon resummation at next-to-next-to-leading-logarithmic order. As an application, we calculate the infrared poles in the q qbar -> t tbar and gg -> t tbar scattering amplitudes at two-loop order.