Jet and Photon Results from ATLAS

Several aspects of the jet and photon production in pp collisions have been measured by the ATLAS collaboration. The measurements of the production cross sections of inclusive jets, dijet,inclusive prompt photons and diphotons probe the dynamics of QCD and can constrain the parton proton structure. The cross sections are measured are compared to expectations based on nexttoleading order QCD calculations, as well as to nexttoleading order Monte Carlo simulations. Ratios of inclusive cross sections measured at different centreofmass energies allow for reduced experimental and/or theoretical uncertainties. Doubledifferential dijet cross sections have been measured in protonproton collisions at 7 TeV as a function of dijet masses and the jet rapidity separation. Measurements of dijet systems with a veto on additional jets, probe QCD radiation effects. The inclusive prompt photon cross sections have been measured over a wide range of transverse momenta; the diphoton cross section has also been measured as a function of diphoton mass, total transverse momentum and azimuthal separation. The cross section for photons produced in association with jets is also measured as a function of various kinematic variables describing the photon+jet system. These measurements constitute precision tests of QCD in a new energy regime.