Inclusive photon cross section at 13 TeV

Measurements of prompt photon production in proton-proton collisions provide a testing ground for perturbative QCD with a hard colourless probe. This kind of measurements were recently used to investigate novel approaches to the description of parton radiation, showcasing the importance of resummation of threshold logarithms in QCD and of electroweak corrections, further they are also sensitive at leading order to the gluon density in the proton. ATLAS has made public very recently the first measurements of inclusive photon production in the new kinematic regime opened by the 13 TeV collisions with an integrated luminosity of 3.2 fb^{-1}. The inclusive photo-production cross section is measured as a function of the photon transverse energy above 125 GeV in different regions of photon pseudorapidity. Next-to-leading-order perturbative QCD and Monte Carlo event-generator predictions are compared to the measured cross section and provide an adequate description of the data.