Measurement of prompt photons with associated jets in photoproduction at HERA

The photoproduction of prompt photons, together with an accompanying jet, has been studied in ep collisions at a centre-of-mass energy of 318 GeV with the ZEUS detector at HERAusing an integrated luminosity of 77 pb-1. Cross sections were measured for the transverseenergy of the photonand the jet larger than 5 and 6 GeV, respectively. The differential γ+jet cross sections were reconstructed as functions of the transverseenergy, pseudorapidityand xγobs, the fraction of the incoming photonmomentum taken by the photon-jet system. Predictions based on leading-logarithm parton-showerMonte Carlo models and next-to-leading-order (NLO) QCD generally underestimate the cross sections for the transverseenergies of prompt photonsbelow 7 GeV, while the kT-factorisation QCD calculation agrees with the data better. When the minimum transverseenergy of prompt photonsis increased to 7 GeV, both NLO QCD and the kT-factorisation calculations are in good agreement with the data.