par Aktas, Adil;Favart, Laurent ;Janssen, Xavier ;Marage, Pierre ; [et al.]
Référence European Physical Journal C. Particles and Fields, 46, 3, page (585-603)
Publication Publié, 2006
Article révisé par les pairs
Résumé : Cross sections for elastic production of J/φ mesons in photoproduction and electroproduction are measured in electron proton collisions at HERA using an integrated luminosity of 55 pb-1. Results are presented for photon virtualities Q2 up to 80 GeV2. The dependence on the photon-proton centre of mass energy Wγp is analysed in the range 40 ≤ Wγp ≤ 305 GeV in photoproduction and 40 ≤ Wγp ≤ 160 GeV in electroproduction. The Wγp dependences of the cross sections do not change significantly with Q 2 and can be described by models based on perturbative QCD. Within such models, the data show a high sensitivity to the gluon density of the proton in the domain of low Bjorken x and low Q2. Differential cross sections dσ/dt, where t is the squared four-momentum transfer at the proton vertex, are measured in the range