Study of photon production also in association with jets with the ATLAS detector

The production of prompt isolated photons at hadron colliders provides a stringent test of perturbative QCD and can be used to probe the gluon density function of the proton. The ATLAS collaboration has performed precise measurements of the inclusive production of isolated prompt photons at a center-of-mass energy of 13 TeV, differential in both rapidity and the photon transverse momentum. In addition, the integrated and differential cross sections for isolated photon pair production and for triple-photon production at 8 TeV have been measured. The results are compared with state-of-the-art theory predictions at NLO in QCD and with predictions of several MC generators. The production of prompt photons in association with jets in proton–proton collisions provides a further testing ground for perturbative QCD (pQCD) with a hard colourless probe less affected by hadronisation effects than jet production alone. We present cross-section measurements performed at cms energies of 8TeV and 13TeV, using final states with hadronic jets in addition to an isolated photon, differential in several kinematic variables describing the photon+jet production dynamic. The results are compared to recent theoretical predictions. We have also measured the cross section for the production of heavy-flavoured jets in association with a photon and studied the impact on the proton structure.