Related papers: Probing the Photon Structure Function in Photoprod…
A first measurement is reported of the longitudinal proton structure function F_L(x,Q^2) at the ep collider HERA. It is based on inclusive deep inelastic e^+p scattering cross section measurements with a positron beam energy of 27.5 GeV and…
We present results for the photoproduction of inclusive prompt photons and for prompt photons accompanied by jets, measured with the ZEUS detector at HERA. Cross sections as a function of pseudorapidity and transverse energy are presented…
A new next-to-leading order Monte Carlo program for the calculation of jet cross sections in photoproduction is described. The contributions from both resolved and direct components are included to O(\alpha \alpha_s^2). Properties of the…
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.
In the framework of the QCD parton model, we study unpolarized scattering of high energy real photons from a proton target into lepton pairs and a system of hadrons. For a given parametrization of parton distributions in the proton, we…
The structure of the photon is studied in photon-photon collisions at LEP. New measurements have become available exploring the structure function F2g of the photon to the lowest values of x yet, where the hadronic component of the photon…
The event structure associated with the production of massive photon pairs is studied to ${\cal O}(\alpha^2/alpha_s)$. The cross sections for two photon and two photon plus one jet events are given. The Dalitz plot structure of events with…
In this contribution we present the main results of the investigation about double parton scattering (DPS) in quasi-real photon-proton interactions. We show the first evaluation of the DPS cross-section at leading-order for the four-jet…
We study the production of photons accompanied by jets in large-Q2 deep inelastic scattering. Numerical results for the cross section differential with respect to the fraction of momentum z_gamma carried by a photon inside a jet at large…
Deeply inelastic scattering of electrons off nuclei can determine whether parton distributions saturate at HERA energies. If so, this phenomenon will also tell us a great deal about how particles are produced, and whether they equilibrate,…
We study J/psi photoproduction via fragmentation at next-to-leading order in the QCD-improved parton model, using the nonrelativistic factorization formalism proposed by Bodwin, Braaten, and Lepage. We consider direct and resolved…
Measurements of inclusive jet and dijet cross sections in photoproduction and deep inelastic scattering are presented. These measurements provide new tests of QCD, constrain the parton densities of the proton and the photon, and allow the…
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…
We present a calculation of the generalized parton distributions of the photon using overlaps of photon light-front wave functions.
Using a recent next-to-leading-order calculation of the photoproduction double differential cross section for heavy quarks, we study the possibility of extracting the gluon density of the proton from heavy-quark photoproduction data. We…
The photoproduction of large-p_T charged hadrons and of prompt photons is discussed, for the inclusive case and with an associated jet, using predictions from the NLO partonic Monte Carlo program EPHOX. Comparisons to recent HERA data are…
We discuss heavy quark and quarkonium production in various kinematic regions at the HERA ep collider. In contrast to fixed target experiments, collider kinematics allows the possibility of detailed measurements of particle production in…
We review recent developments in the theoretical description of inclusive single-hadron production at next-to-leading order in the parton model of quantum chromodynamics. Fragmentation functions are extracted from fits to data of inclusive…
Recent results of open charm and beauty production in electron proton scattering at HERA are presented. In photoproduction, the measured cross sections for charm exceed fixed order NLO QCD calculations. Experimental evidence supports the…
We calculate the differential cross section for real photon electroproduction off spinless hadron which sevres as a main probe of the hadrons structure via the concept of generalized parton distributions. Compared to previously available…