Three-loop helicity amplitudes for quark-gluon scattering in QCD

Abstract

We compute the three-loop helicity amplitudes for $q\bar{q}\to gg$ and its crossed partonic channels, in massless QCD. Our analytical results provide a non-trivial check of the color quadrupole contribution to the infrared poles for external states in different color representations. At high energies, the $qg\to qg$ amplitude shows the predicted factorized form from Regge theory and confirms previous results for the gluon Regge trajectory extracted from $q{q}^{\prime }\to q{q}^{\prime }$ and $gg\to gg$ scattering.

Comments: 32 Pages, 4 figures, ancillary files with analytical results