Measurement of the Production Cross Section of an Isolated Photon Associated With Jets in Proton-Proton Collisions at ?s=7tev 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=7TeV is presented. Photons are reconstructed in the pseudorapidity range |??|<1.37 and with a transverse energy ET?>25GeV. Jets are reconstructed in the rapidity range |yjet|<4.4 and with a transverse momentum pTjet>20GeV. The differential cross section d?/dET? is measured, as a function of the photon transverse energy, for three different rapidity ranges of the leading-pT jet: |yjet|<1.2, 1.2?|yjet|<2.8 and 2.8?|yjet|<4.4. For each rapidity configuration the same-sign (??yjet 0) and opposite-sign (??yjet<0) cases are studied separately. The results are based on an integrated luminosity of 37pb-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 ET? 45GeV, where the theoretical predictions overestimate the measured cross sections. © 2012 CERN.