Elastic and Proton-Dissociative Photoproduction of J/psi Mesons at HERA

H1 Collaboration

Paper

Elastic and Proton-Dissociative Photoproduction of J/psi Mesons at HERA

Abstract

Cross sections for elastic and proton-dissociative photoproduction of J/psi mesons are measured with the H1 detector in positron-proton collisions at HERA. The data were collected at

centre-of-mass energies sqrt{s} approx 318 GeV and sqrt{s} approx 225 GeV, corresponding to integrated luminosities of L = 130 pb^{-1} and L = 10.8 pb^{-1}, respectively. The cross sections are measured as a function of the photon-proton centre-of-mass energy in the range 25< Wgp < 110 GeV. Differential cross sections

, where

is the squared four-momentum transfer at the proton vertex, are measured in the range

for the elastic process and

for proton dissociation. The results are compared to other measurements. The

and

-dependences are parametrised using phenomenological fits.