1112.1531 (Thomas Gehrmann et al.)

Two-loop QCD helicity amplitudes for $q\bar q \to W^\pm γ$ and
$q\bar q \to Z^0 γ$    [PDF]

Thomas Gehrmann, Lorenzo Tancredi

The self-couplings of the electroweak gauge bosons are probed at hadron
colliders through the production of a massive gauge boson and a photon. To
extend the theoretical description of this type of final states towards
next-to-next-to-leading order (NNLO) in QCD, we derive the two-loop QCD
corrections to the helicity amplitudes describing the production of a massive
gauge boson in association with a real photon. Our results are obtained by
applying projectors to the general parton-level tensor structure. The leptonic
decay of the vector boson is included, thus allowing for a fully exclusive
description of the final state. The infrared poles of the amplitudes are
described by an infrared factorization formula. We provide an analytic
expression for the finite remainder of the amplitude in terms of one- and
two-dimensional harmonic polylogarithms. The amplitudes are expressed in the
physical kinematics relevant to gauge-boson-plus-photon production at hadron
colliders. As a by-product, we also derive the two-loop QCD amplitudes for
vector-boson-plus-jet production at hadron colliders.

View original: http://arxiv.org/abs/1112.1531