Photon isolation effects at NLO in gamma gamma + jet final states in hadronic collisions

TL;DR

This work delivers NLO QCD predictions for diphoton production in association with a jet at hadron colliders, incorporating jet-to-photon fragmentation to enable arbitrary infrared-safe photon isolation definitions. The authors implement a fully automated framework combining MadGraph, MadDipole, MadEvent, and GoSam to compute real and virtual corrections and handle photon fragmentation through fragmentation functions. They systematically compare cone-based, democratic clustering, and smooth-cone isolations (Frixione), revealing distinct scale behaviors and K-factors, especially in exclusive versus inclusive production. A public code release (gosam/diphoton) facilitates future studies and potential matching to parton showers.

Abstract

We present the NLO QCD corrections to diphoton plus jet production at hadron colliders. Our calculation includes contributions from the fragmentation of a hadronic jet into a highly energetic photon, and consequently allows the implementation of arbitrary infrared-safe photon isolation definitions. We compare different photon isolation criteria and perform a detailed study of the dependence of the diphoton plus jet cross section on the photon isolation parameters.