Vector meson production at HERA.

Exclusive [lowercase_phi_synonym] electroproduction and proton-dissociative diffractive photoproduction of J/ψ mesons has been studied in ep collisions with the ZEUS detector at HERA, using an integrated luminosity of 65 pb-1 and 112 pb-1, respectively. The [lowercase_phi_synonym] cross section was measured as a function of Q2, W, t and helicity angle θh in the kinematic range of 2 < Q2 < 70 GeV2, 35 < W < 145 GeV and |t| < 0.6 GeV2. The J/ψ photoproduction cross section was measured for |t| up to 20 GeV2 in the range of 50 < W < 150 GeV as a function of |t| and W. Both measurements are compared to other vector meson cross sections and predictions from theoretical models. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]