Related papers: $J/\psi$ photoproduction at HERA
Exclusive diffractive photoproduction of heavy vector mesons (V=phi, J/psi and Upsilon) at HERA is studied in a model employing a dipole Pomeron exchange (P) with an inelastic gamma-P-V vertex. The model is fitted to the data on dsigma/dt,…
An earlier developed model for vector meson photoproduction, based on a dipole Pomeron exchange, is extended to electroproduction. Universality of the non linear Pomeron trajectory is tested by fitting the model to ZEUS and H1 data as well…
Recent $HERA$ data on the photoproduction of vector mesons are analysed within a "soft", dipole pomeron model. We argued that the data on $\sigma^{\gamma\rightarrow J/\psi}_{el}$ is consistent with a soft pomeron, the apparent rapid…
The low energy $J/\psi$ photoproduction cross-section has been studied on the basis of the Pomeron model. To incorporate the discrepancy between experimental data and the predictionns by the conventional models, i.e. the sum of the soft…
Recent small-t ZEUS data for exclusive rho photoproduction are in excellent agreement with exchange of the classical soft pomeron with slope alpha'=0.25 GeV^{-2}. Adding in a flavour-blind hard-pomeron contribution, whose magnitude is…
The exclusive photoproduction of J/psi mesons, gamma p->J/psi p, has been studied in ep collisions with the ZEUS detector at HERA, in the kinematic range 20<W<290 GeV, where W is the photon-proton centre-of-mass energy. The J/psi mesons…
The exclusive electroproduction of J/psi mesons, ep->epJ/psi, has been studied with the ZEUS detector at HERA for virtualities of the exchanged photon in the ranges 0.15<Q^2<0.8 GeV^2 and 2<Q^2<100 GeV^2 using integrated luminosities of 69…
It is demonstrated that the "soft pomeron" (together with a secondary reggeon) describing cross-sections of hadron-hadron collisions is fairly able to describe the energy dependence of cross-sections of exclusive (virtual) photoproduction…
The ZEUS data on the charm structure function F_2^c at small x fit well to a single power of x, corresponding to the exchange of a hard pomeron that is flavour-blind. When combined with the contribution from the exchange of a soft pomeron,…
The proton-dissociative diffractive photoproduction of J/psi mesons has been studied in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 112 pb^-1. The cross section is presented as a function of the…
An earlier developed model for vector meson photoproduction, based on a dipole Pomeron exchange, is extended to electroproduction. Universality of the non linear Pomeron trajectory is tested by fitting the model to ZEUS and H1 data as well…
Exclusive photoproduction of all vector mesons by real and virtual photons is considered in the Soft Dipole Pomeron model. It is emphasized that being the Pomeron in this model a double Regge pole with intercept equal to one, we are led to…
Exclusive photoproduction of all vector mesons by real and virtual photons is considered in the Soft Dipole Pomeron model. It is emphasized that being the Pomeron in this model a double Regge pole with intercept equal to one, we are led to…
This report is a short overview of experimental and theoretical results in J/psi production in electron-proton collisions at DESY HERA with special focus lying on recent developments in inelastic photoproduction.
We evaluate the large momentum transfer $J/\psi$ photoproduction with rapidity gaps in ultraperipheral proton-ion collisions at the LHC which provides an effective method of probing dynamics of large t elastic hard QCD Pomeron interactions.…
The diffractive photoproduction of J/psi mesons is measured with the H1 detector at the ep collider HERA using an integrated luminosity of 78 pb^-1. The differential cross section d sigma(gamma p -> J/psi Y) / d t is studied in the range 2…
The cross sections for inelastic photoproduction of J/psi and psi' mesons have been measured in ep collisions with the ZEUS detector at HERA, using an integrated luminosity of 38.0 pb-1. The events were required to have 0.1 < z < 0.9 and 50…
The H1 and ZEUS Collaborations report new results on elastic VM cross-section and trajectory determination. Elastic VM production appears to be independent of the photon polarization. The presence of non-zero shrinkage in the…
We present a measurement of the inelastic, non diffractive J/$\psi$ photoproduction cross section in the reaction $e^{+} p \to e^{+} {J}/\psi X$ with the ZEUS detector at HERA. The J/$\psi$ was identified using both the $\mu^{+}\mu^{-}$ and…
The photoproduction of isolated photons has been measured in diffractive events recorded by the ZEUS detector at HERA. Cross sections are evaluated in the photon transverse-energy and pseudorapidity ranges $5 < E_T < 15$ GeV and $-0.7 <…