Two-loop leading colour helicity amplitudes for W±γ + j production at the LHC

Abstract

Abstract We present the two-loop leading colour QCD helicity amplitudes for the process pp → W (→ lν)γ + j. We implement a complete reduction of the amplitudes, including the leptonic decay of the W-boson, using finite field arithmetic, and extract the analytic finite remainders using a recently identified basis of special functions. Simplified analytic expressions are obtained after considering permutations of a rational kinematic parametrisation and multivariate partial fractioning. We demonstrate efficient numerical evaluation of the two-loop colour and helicity summed finite remainders for physical kinematics, and hence the suitability for phenomenological applications.