Measurement of the differential γ +2b-jet cross section and the ratio σ(γ +2b-jets)/σ(γ +b-jet) in p ¯p collisions at √s=1.96 TeV

We present the first measurements of the differential cross section dσ/dpγ T for the production of an isolated photon in association with at least two b-quark jets. The measurements consider photons with rapidities |yγ | 15 GeVand |yjet| < 1.5. The ratio of differential production cross sections for γ + 2 b-jets to γ +b-jet as a function of pγT is also presented. The results are based on the proton–antiproton collision data at √s = 1.96 TeVcollected with the D0 detector at the Fermilab Tevatron Collider. The measured cross sections and their ratios are compared to the next-to-leading order perturbative QCD calculations as well as predictions based on the kT-factorization approach and those from the sherpa and pythia Monte Carlo event generators.