Two-loop helicity amplitudes for diphoton plus jet production in full color

TL;DR

This work presents the first full-color two-loop QCD corrections to all helicity amplitudes for diphoton plus jet production, a 2→3 five-point process. The authors compute analytically all helicity amplitudes for the q q̄, qg, and g q̄ channels, perform UV renormalization and IR factorization via Catani's formalism, and reduce two-loop integrals to master integrals using IBP with Reduze 2 and Finred, expressing results in pentagon functions. They validate their results against independent checks (OpenLoops, pole structure, and polarization-interference) and provide compact, fast-evaluated finite remainders for all color structures, enabling N^3LO predictions for diphoton production at the LHC. This advances precision collider phenomenology by removing the leading-color approximation and delivering complete two-loop amplitudes for a five-point process.

Abstract

We present the complete two-loop corrections in massless QCD for the production of two photons and a jet, taking into account all color structures. In particular, we analytically compute all two-loop helicity amplitudes for the quark-antiquark, quark-gluon, and antiquark-gluon channel, and check them with an independent calculation of the polarization-summed interference with the tree amplitude. This is the first time that two-loop QCD corrections to a five-point scattering process have been computed beyond the leading-color approximation for all helicity configurations.