Measurement of the differential isolated prompt photon production cross section in pp collisions at 7 TeV center - of - mass energy

In this paper we present two measurements : the measurement of the differential cross section for the inclusive production of isolated prompt photons [1], and the measurement of the production of pairs of prompt isolated photons [2] in proton-proton collisions at a centre-of-mass energy of 7 TeV with the Compact Muon Sollenoid (CMS) detector at the Large Hadron Collider (LHC). A data sample corresponding to an integrated luminosity of 36 pb−1 is analyzed. The next-toleading-order perturbative QCD calculations are consistent with the measured differential cross section for the inclusive photon production, while the diphoton differential cross-section shows a discrepancy for regions of the phase space where the two photons have an azimuthal angle difference ∆φ < 2.8.