Double parton interactions in photon + 3 jets events in $p\bar{p}$ collisions at sqrt(s)=1.96 TeV

We have used a sample of photon+3 jets events collected by the D0 experiment with an integrated luminosity of about 1 fb$^{-1}$ to determine the fraction of events with hard double parton (DP) scattering in a single $p\bar{p}$ collision at sqrt(s)=1.96 TeV. The DP fraction and effective cross section, a process-independent scale parameter related to the parton density inside the nucleon, are measured in three intervals of the second (ordered in pT) jet transverse momentum 15 - 30 GeV range.