Measurement of the isolated diphoton cross section in $pp$ collisions at √s=7  TeV with the ATLAS detector

The ATLAS experiment has measured the production cross section of events with two isolated photons in the final state, in proton-proton collisions at √s=7 TeV. The full data set acquired in 2010 is used, corresponding to an integrated luminosity of 37 pb⁻¹. The background, consisting of hadronic jets and isolated electrons, is estimated with fully data-driven techniques and subtracted. The differential cross sections, as functions of the di-photon mass (m𝛾⁢𝛾), total transverse momentum (pT,𝛾⁢𝛾), and azimuthal separation (𝛥⁢𝜙𝛾⁢𝛾), are presented and compared to the predictions of next-to-leading-order QCD.