PHOTOPRODUCTION OF J/ψ MESONS AT HIGH ENERGIES IN PARTON MODEL AND k⊤-FACTORIZATION APPROACH

We consider J/ψ meson photoproduction on protons at high energies at the leading order in αs using conventional parton model and k⊤-factorization approach of QCD. It is shown that in the both cases the colour singlet mechanism gives correct description for experimental data from HERA for the total cross section and for the J/ψ meson z-spectrum at realistic values of a c-quark mass and meson wave function at the origin Ψ(0). At the same time our predictions for p⊤-spectrum of J/ψ meson and for p⊤ dependence of the spin parameter α obtained in k⊤-factorization approach are very different from the results obtained in conventional parton model. Such a way the experimental study of a polarized J/ψ meson production at the large p⊤ should be a direct test of BFKL gluons.