First inclusive measurements of isolated prompt photons in photoproduction at the HERA ep collider have been made with the ZEUS detector, using an integrated luminosity of 38.4 pb-1. Cross sections are given as a function of the pseudorapidity and the transverse energy (ηγ, Eγ . of the photon, for E>5 GeV in the γ p centre-of-mass energy range T T 134-285 GeV. Comparisons are made with predictions from Monte Carlo models having leading-logarithm parton showers, and with next-To-leading-order QCD calculations, using currently available parameterisations of the photon structure. For forward ηγ (proton direction. good agreement is found, but in the rear direction all predictions fall below the data.
|Number of pages||14|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|State||Published - Jan 13 2000|