Photon, di-photon and photon+jet production measured with the ATLAS detector

Isolated prompt photons provide a direct probe of short­-distance physics, complementary to that provided by measurements of jets or vector-bosons. The data are sensitive to the gluon density of the proton. The inclusive prompt photon cross sections have been measured over a wide range of transverse momenta; the di-photon cross section has also been measured as a function of di-photon mass, total transverse momentum and azimuthal separation; the cross section for photons produced in association with jets is also measured. The results are compared to the predictions of next-­to-­leading-­order QCD.