Measurement of the Production Cross Section for Pairs of Isolated Photons in pp collisions at sqrt(s) = 7 TeV

TL;DR

This paper reports measurements of isolated photon pair production cross sections in proton-proton collisions at 7 TeV, comparing results with QCD predictions and identifying discrepancies in specific phase space regions.

Contribution

The study provides the first detailed measurement of photon pair production cross sections at 7 TeV and compares them with NLO QCD calculations, highlighting areas of disagreement.

Findings

Measured cross sections agree with QCD predictions in most regions.

Discrepancies observed when the azimuthal angle difference is less than 2.8 radians.

Results help refine theoretical models of photon pair production.

Abstract

The integrated and differential cross sections for the production of pairs of isolated photons is measured in proton-proton collisions at a centre-of-mass energy of 7 TeV with the CMS detector at the LHC. A data sample corresponding to an integrated luminosity of 36 inverse picobarns is analysed. A next-to-leading-order perturbative QCD calculation is compared to the measurements. A discrepancy is observed for regions of the phase space where the two photons have an azimuthal angle difference, Delta(phi), less than approximately 2.8.