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We study the photoproduction of the vector mesons $Phi$ and $J/Psi$ off a proton in the kinematical regime of large energies and scattering angles within the framework of perturbative QCD. Our investigations are based on the hard scattering approach. This means that the hadrons are replaced by their valence Fock states and scattering on the partonic level is described by tree graphs in which the large transferred momentum is redistributed between the valence partons via the exchange of hard gluons. We find that the unpolarized photoproduction cross sections are dominated by Compton-scattering-like graphs in which the photon couples to the proton, whereas vector-meson-dominance-like graphs, in which the photon fluctuates into the heavy quark-antiquark pair which then exchanges two gluons with the proton, play a minor role. We give explicit predictions for unpolarized scattering cross sections and compare them with experimental data where possible.
We calculate the leading-order perturbative contribution to $gamma p to M_{V} p$, with $M_V$ being a $Phi$ or $J/Psi$ meson, in the kinematic region of large energy and scattering angle.
The near-threshold photoproduction of $J/psi$ is regarded as one golden process to unveil the nucleon mass structure, pentaquark state involving the charm quarks, and the poorly constrained gluon distribution of the nucleon at large $x$ ($>0.1$). In
We report on an attempt to describe hard exclusive photoproduction of $J/Psi$ mesons, i.e. the reaction $gamma p to J/Psi p$, by means of a modified version of the hard-scattering approach, in which the proton is treated as a quark-diquark rather tha
We present $Phi$- and $J/Psi$--nuclear bound state energies and absorption widths for some selected nuclei, using potentials in the local density approximation computed from an effective Lagrangian approach combined with the quark-meson coupling mode
We report on the measurement of the $gamma p rightarrow J/psi p$ cross section from $E_gamma = 11.8$ GeV down to the threshold at $8.2$ GeV using a tagged photon beam with the GlueX experiment. We find the total cross section falls toward the thresho