Measurement of the differential cross sections for isolated direct photon pair production in $p \bar p$ collisions at $\sqrt{s} = 1.96$ TeV
Phys.Lett. B725 (2013) 6-14
The collaboration

Abstract (data abstract)
Fermilab-Tevatron. Measurements of the differential distributions of isolated direct photon pair production in antiproton-proton collisions at a centre-of-mass energy of 1.96 TeV. The data sample, with integrated luminosity 8.5 fb-1, is used to determine the photon pair differential mass distribution (DSIG/DMT), the transverse momentum distribution (DSIG/DPT), the distribution in the azimuthal angle between the two photons (DSIG/D(PHI1-DPHI2) and the polar scattering angle angle distribution in the Collins-Soper frame (DSIG/D|COS(THETA*)|. The measurements require isolated photons with PT > 18 (17) for the leading (next-to-leading) photons having |eta|<0.9 and separation from each other in eta-phi space > 0.4.