Elastic and proton-dissociative photoproduction of J/ψ mesons at HERA

Cross sections for elastic and proton-dissociative photoproduction of J/ψ mesons are measured with the H1 detector in positron-proton collisions at HERA. The data were collected at ep centre-of-mass energies √(s)∼318 GeV and √(s)∼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<Wγp<110 GeV. Differential cross sections dσ/dt, where t is the squared four-momentum transfer at the proton vertex, are measured in the range vertical stroke t vertical stroke <1.2 GeV2 for the elastic process and vertical stroke t vertical stroke <8 GeV2 for proton dissociation. The results are compared to other measurements. The Wγp and t-dependences are parametrised using phenomenological fits.