Double parton interactions in photon + 3 jet and photon + b/c jet + 2 jet events in ppbar collisions at sqrt{s}=1.96 TeV

We determine the fraction of events with double parton (DP) scattering in a single p ¯ p collision at √ s = 1 . 96 TeV in samples of γ + 3 jet and γ + b/c jet + 2 jet events collected with the D0 detector and corresponding to an integrated luminosity of about 8.7 fb − 1 . The DP fractions and effective cross sections ( σ eff ) are measured for both event samples using the same kinematic selections. The measured DP fractions range from 0 . 21 to 0 . 17, with effective cross sections in the γ + 3 jet and γ + b/c jet + 2 jet samples of σ incl eff = 12 . 7 ± 0 . 2 (stat) ± 1 . 3 (syst) mb and σ HF eff = 14 . 6 ± 0 . 6 (stat) ± 3 . 2 (syst) mb, respectively.