Leading Color Two-Loop QCD Corrections for Three-Photon Production at Hadron Colliders
I will discuss the very recent calculation of the two-loop helicity amplitudes for the production of three photons at hadron colliders in leading-color QCD. Using the two-loop numerical unitarity method, coupled with analytic reconstruction techniques, we obtained the amplitudes as a decomposition in terms of master integrals and the associated two-loop remainders. The remainders are given in a form that can be efficiently evaluated across the whole physical phase space in a numerically stable manner. This is the first time that a five-point two-loop process is publicly available for immediate phenomenological applications.