Related papers: $J/\psi$ photoproduction at HERA
Diffractive photoproduction of dijets was measured with the ZEUS detector at the ep collider HERA using an integrated luminosity of 77.2 pb-1. The measurements were made in the kinematic range Q^2 < 1 GeV^2, 0.20 < y < 0.85 and x_pom <…
Recent results on diffraction at HERA, from the H1 and ZEUS Collaborations, and at Tevatron, from the CDF and D0 Collaborations, are reviewed. The measurement of the diffractive structure function at HERA is presented, and the pomeron…
The photoproduction of $D^{*\pm}$ mesons has been measured with the ZEUS detector at HERA at three different ep centre-of-mass energies, $\sqrt{s}$, of 318, 251 and 225 GeV. For each data set, $D^*$ mesons were required to have transverse…
Diffractive meson production at HERA offers interesting possibilities to investigate diffractive processes and thus to learn something about the properties of the pomeron. The most succesful phenomenological description of the pomeron so…
The tensor-pomeron model is applied to low-x deep-inelastic lepton-nucleon scattering and photoproduction. We consider c.m. energies in the range 6 - 318 GeV and Q^2 < 50 GeV^2. In addition to the soft tensor pomeron, which has proven quite…
We study pp and p\bar p collisions which lead to the exclusive production of J/psi or Upsilon from the pomeron-odderon and the pomeron-photon fusion. We calculate scattering amplitudes of these processes in the lowest order approximation…
The exclusive photoproduction reaction gamma p --> Upsilon p has been studied with the ZEUS experiment in ep collisions at HERA using an integrated luminosity of 468 pb^{-1}. The measurement covers the kinematic range 60<W<220 GeV and Q^2<1…
In this contribution we study for the first time the prompt photon production in single and double diffractive processes considering the resolved Pomeron model. We estimate the rapidity and transverse momentum dependence of the cross…
The cross section for exclusive $\Upsilon$ ultraperipheral photoproduction at present and future colliders is determined using the low $x$ gluon PDF extracted from an analysis of exclusive $J/\psi$ measurements performed at HERA and the…
A Pomeron-exchange model of exclusive electroproduction of $\rho$-mesons is examined using a dressed-quark propagator. It is shown that by representing the photon-$\rho$-meson-Pomeron coupling by a nonperturbative, confined-quark loop, one…
Photoproduction of beauty quarks in events with two jets and an electron associated with one of the jets has been studied with the ZEUS detector at HERA using an integrated luminosity of 120pb^-1. The fractions of events containing b…
The comparison of $J/\psi$ photoproduction data in the inelastic region with theoretical predictions based on the NRQCD approach has remained somewhat ambiguous and controversial, in particular at large values of the inelasticity variable…
Jpsi and dielectron photoproduction measurements in ultra-peripheral Au+Au collisions at 200 GeV with the PHENIX experiment are presented. The triggered events correspond to those accompanied with forward neutron emission from the Au…
We present calculations of the beauty photoproduction at HERA collider in the framework of the kt-factorization approach. Both direct and resolved photon contributions are taken into account. The unintegrated gluon densities in a proton and…
We analyze contributions to the heavy vector meson production with large transverse momentum in proton--proton and diffractive photon--proton scattering driven by an exchange of two Balitsky--Fadin--Kuraev--Lipatov Pomerons in the squared…
The production of heavy quarks has been studied in photoproduction processes with the ZEUS detector at HERA using an integrated luminosity of $36.9 pb^{-1}$. Events with a photon virtuality, $Q^2<1 GeV^2$, were selected with two jets of…
The production of $J/\psi$-pairs as a possible measure of the polarized gluon distribution $\Delta G(x)$ is studied for proton--nucleon collisions at $\sqrt{s} =40\;\mbox{GeV}^2$ (HERA-$\vec{{\rm N}}$). Possibilities of reconstructing the…
We consider the reaction $\gamma p \to M p$, with M being either a $\Phi$ or a $J/\Psi$ meson, within perturbative QCD treating the proton as a quark-diquark system. The phenomenological couplings of gauge bosons to (spatially extended)…
We report on the potentialities offered by a fixed-target experiment at the LHC using the proton and ion LHC beams (AFTER@LHC project) regarding the study of J/psi exclusive-photoproduction in pA and AA collisions. The foreseen usage of…
Photoproduction of beauty quarks in events with two jets and an electron associated with one of the jets has been studied with the ZEUS detector at HERA using an integrated luminosity of 120 pb-1. The fractions of events containing b…