Measurement of the production cross section of an isolated photon associated with jets in proton-proton collisions at √s=7 TeV with the ATLAS detector

Abstract

A measurement of the cross section for the production of an isolated photon in association with jets in proton-proton collisions at a center-of-mass energy √s=7  TeV is presented. Photons are reconstructed in the pseudorapidity range |η^γ|<1.37 and with a transverse energy E_T^γ>25  GeV. Jets are reconstructed in the rapidity range |y^(jet)|<4.4 and with a transverse momentum p_T^(jet)>20  GeV. The differential cross section dσ/dE_T^γ is measured, as a function of the photon transverse energy, for three different rapidity ranges of the leading-p_T jet:|y^(jet)|<1.2, 1.2≤|y^(jet)|<2.8 and 2.8≤|y^(jet)|<4.4. For each rapidity configuration the same-sign (η^γy^(jet)≥0) and opposite-sign (η^γy^(jet)<0) cases are studied separately. The results are based on an integrated luminosity of 37  pb^(-1), collected with the ATLAS detector at the LHC. Next-to-leading order perturbative QCD calculations are found to be in fair agreement with the data, except for E_T^γ≲45  GeV, where the theoretical predictions overestimate the measured cross sections.

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