A two-loop four-gluon helicity amplitude in QCD

Abstract

We present the two-loop pure gauge contribution to the gluon-gluon scattering amplitude with maximal helicity violation. Our construction of the amplitude does not rely directly on Feynman diagrams, but instead uses its analytic properties in 4 - 2ε dimensions. We evaluate the loop integrals appearing in the amplitude through O(ε0) in terms of polylogarithms.