相关论文: Exclusive Vector Photoproduction: Confirmation of …
We revise and update an earlier model for $J/\psi$ photoproduction based on a dipole Pomeron exchange. We show that the H1 and ZEUS experimental data reported recently can be well fitted by a soft Pomeron alone.
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,…
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 processes of exclusive photo- and electroproduction of vector mesons $\rho^0$(770), $\phi$(1020) and $J/\psi$(3096) at collision energies $30 GeV<W<300 GeV$ and transferred momenta squared $0<-t<2 GeV^2$ are considered in the framework…
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…
The elastic differential and integrated total cross section for the exclusive $\rho^0$ photoproduction in electron-proton ($ep$) collisions are evaluated taking into account nonperturbative Pomeron exchange approach. By using three…
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…
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…
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 <…
Exclusive rho0 electroproduction at HERA has been studied with the ZEUS detector, using 120 pb{-1} integrated luminosity, in the kinematic range of photon virtuality of 2 < Q2 < 160 GeV2, and gamma* p center-of-mass energy of 32 < W < 180…
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-proton transverse-energy and pseudorapidity ranges 5<ET(gamma)<15 GeV and…
A model based on a dipole Pomeron framework for vector meson exclusive photoproduction by real and virtual photons shows very good agreement with the experimental data. The model does not violate unitarity constrains and describes in a…
Hard, or high transverse momentum, pion photoproduction can be a tool for probing the parton structure of the beam and target. We estimate the soft contributions to this process, with an eye toward delineating the region where…
Understanding the spin dynamics of strong interactions from the nonperturbative to the perturbative regime remains a challenge. Regge pole theory offers a phenomenological framework, but existing models fail to simultaneously describe cross…
We present results from recent investigations of diffractive vector meson production using the ZEUS detector at HERA. These consist of measurements of rho production in the region of photon virtuality 0.25 < Q^2 < 0.85 GeV^2, of rho, phi,…
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…
We investigate the possibility that the process of phi photoproduction may have a significant hard perturbative QCD component. This suggestion is based on a study of the energy dependence of the forward phi photoproduction cross section…
Protons and antiprotons at collider energies are a source of high energy Weizs\"acker--Williams photons. This may open a possibility to study exclusive photoproduction of heavy vector mesons at energies much larger than possible at the HERA…
Inclusive jet cross sections for events with a large rapidity gap with respect to the proton direction from the reaction $ep \rightarrow jet \; + \; X$ with quasi-real photons have been measured with the ZEUS detector. The cross sections…
We apply the tensor-pomeron model to small-$x$ deep-inelastic lepton-proton scattering and photoproduction. Our model includes a soft and a hard tensor pomeron as well as a reggeon contribution. Data with c.m. energies $6 < \sqrt{s} < 318$…