Аннотация
Abstract The cross sections for inelastic photoproduction ofJ/ψandψ′ mesons have been measured inepcollisions with the ZEUS detector at HERA, using an integrated luminosity of 468 pb−1collected in the period 1996–2007. Theψ′ toJ/ψ cross section ratio was measured in the range 0.55 < z < 0.9 and 60 < W < 190 GeV as a function ofW,zandpT. HereWdenotes the photon-proton centre-of-mass energy,zis the fraction of the incident photon energy carried by the meson andpTis the transverse momentum of the meson with respect to the beam axis. TheJ/ψcross sections were measured for 0.1 < z < 0.9, 60 < W < 240 GeV andpT > 1 GeV. Theoretical predictions within the non-relativistic QCD framework including NLO colour-singlet and colour-octet contributions were compared to the data, as were predictions based on thekT-factorisation approach.