Related papers: Some Aspects of Polarized ep Scattering at HERA
Little information is known about the polarization of gluons inside a longitudinally polarized proton. I report on the sensitivity of photoproduction experiments to it. Both jet and heavy quark production are considered.
We investigate the possibility to identify photon-gluon fusion (PGF) events in polarised deep inelastic ep scattering, assuming the kinematics of the HERA collider, by a pair of charged high p_t particles. In a Monte Carlo study we find…
Cross sections for elastic and proton-dissociative photoproduction of J/psi mesons are measured with the H1 detector in positron-proton collisions at HERA. The data were collected at $ep$ centre-of-mass energies sqrt{s} approx 318 GeV and…
We consider the dependencies of spin asymmetries in the diffractive $J/\Psi$ and $Q \bar Q$ leptoproduction at HERA energies on the structure of the pomeron-proton coupling. It is shown that it is difficult to study the spin structure of…
The production of prompt photons is measured in the photoproduction regime of electron-proton scattering at HERA. The analysis is based on a data sample corresponding to a total integrated luminosity of 340 pb^-1 collected by the H1…
The production rates of lepton-photon and dimuon pairs at the HERA collider and the HERMES experiment are evaluated in the leading order equivalent photon approximation. It is shown that the production rates are sufficient to facilitate the…
The latest measurements of the cross sections for neutral and charged current deep inelastic scattering in e+/-p collisions at HERA with longitudinally polarised lepton beams are presented. The measured cross sections are compared with the…
The photoproduction of Drell-Yan lepton pairs at HERA is studied. We show that in the backward rapidity region the cross section is strongly sensitive to the small-$x$ behaviour of the quark distributions in the proton, and that with…
Photon-proton ($\gamma p$) interactions with~$Q^2<10^{-2}$~GeV$^2$ and deep-inelastic scattering ($\gamma^* p$) interactions with photon virtualities $Q^2>5$~GeV$^2$ are studied at the high energy electron-proton collider HERA. The…
HERA measurements of diffractive ep scattering - the quasi-elastic scattering of the photon in the proton colour field - are summarised. Emphasis is placed on the most recent data.
We explore the discovery and analysis potentials of the HERA collider, with and without polarized beams, in search for electron-quark contact interactions in the neutral current channel. We find that the sensitivity to contact interactions…
Little information is known about the polarization of gluons inside a longitudinally polarized proton. We investigate the sensitivity of photoproduction experiments with both beam and target longitudinally polarized to the polarization of…
Cross sections for the production of two isolated muons up to high di-muon masses are measured in ep collisions at HERA with the H1 detector in a data sample corresponding to an integrated luminosity of 71 pb^-1 at a centre of mass energy…
We present here some arguments to support our suggestion that data on the helicity structure for the hard exclusive electroproduction of $\rho$ mesons at HERA (and in possible future high-energy electron-proton colliders) provide useful…
A measurement of the inclusive ep scattering cross section is presented in the region of low momentum transfers, 0.2 GeV^2 < Q^2 < 12 GeV^2, and low Bjorken x, 5x10^-6 < x < 0.02. The result is based on two data sets collected in dedicated…
The semi-inclusive reaction e+ p -> e+ X p was studied with the ZEUS detector at HERA using an integrated luminosity of 12.8 pb-1. The final-state proton, which was detected with the ZEUS leading proton spectrometer, carried a large…
We study the production of transversely polarized Lambda hyperons in high-energy collisions of protons with large nuclei. The large gluon density of the target at saturation provides an intrinsic semi-hard scale which should naturally allow…
We discuss the potential of polarized HERA to measure the spin dependent part of the total photoproduction cross-section at large $\sqrt{s_{\gamma p}}$.
Processes of hevy quark photoproduction at HERA energies and beyond are investigated using the semihard ($k_{\bot}$ factorization) approach. The virtuality and longitudinal polarization of gluons in the photon - gluon subprocess as well as…
We calculated the color-octet contribution to the double spin asymmetry of $J/\psi$ hadroproduction with nonzero transverse momenta at fixed target energies $\sqrt{s}\simeq40$ GeV. It is shown that the color-octet contribution is dominant…