Related papers: The virtual photon structure at HERA
The parton momentum densities in the proton are obtained from a NLO QCD analysis of structure functions measured by HERA and fixed target experiments. The uncertainties in these parton densities, the structure functions and related cross…
Recent structure function results from H1 and ZEUS are presented. The data have been recorded in e+p and e-p collisions for both Neutral Current and Charged Current reactions, covering a wide kinematic range of squared four-momentum…
Selected ZEUS results on the proton and the photon structures are presented. A short outline of the future measurements, the HERA machine and the ZEUS detector status is given.
Recent NLO calculations for the photoproduction of one and two jets at HERA are compared to data from H1 and ZEUS. We discuss the physics potential of these measurements for constraining the photon structure, especially the quark density at…
Parameter-free and perturbatively stable leading order (LO) and next-to-leading order (NLO) parton densities for real and virtual photons are presented.
Jet production in $ep$ collisions is sensitive to the partonic structure of photon. The latest measurements of dijet production from the H1 experiment provide new results of the gluon density of real photons at low $x$ and, for the first…
A combination of the reduced $e^{\pm}p$ cross section, previously measured by H1 and ZEUS, has been performed and leads to well constrained QCD fits of the parton densities in the proton. These results, as well as the high-$Q^2$ neutral…
HERA has provided a wealth of high precision structure function and jet production data, allowing considerable progress to be made in understanding the structure of the proton. In this paper, several of the most recent proton structure…
The photon structure function is a useful testing ground for QCD. It is perturbatively computable apart from a contribution from what is usually called the hadronic component of the photon. There have been many proposals for this…
The structure of the photon is probed in photon-photon interactions at LEP and in photon-proton interactions at HERA.
The ZEUS detector has been used to study dissociation of virtual photons in events with a leading proton, gamma^* p -> X p, in e^+p collisions at HERA. The data cover photon virtualities in two ranges, 0.03<Q^2<0.60 GeV^2 and 2<Q^2<100…
Measurements of proton structure functions made in neutral and charged current interactions at HERA are discussed, covering four-momentum transfers Q^2 from about 0.5 GeV^2 to 30000 GeV^2. The results include the rise of the structure…
The transition between photoproduction and deep-inelastic scattering is investigated in jet production at the HERA ep collider, using data collected by the H1 experiment. Measurements of the differential inclusive jet cross-sections…
At HERA, the electron-proton collider at DESY, Hamburg, the large flux of almost on-shell photons accompanying the lepton beam is being used to shed new light on the structure of the photon. Recent results are reviewed and discussed, with…
We point out that in processes involving the parton content of the photon the usual effective photon approximation should be modified. The reason is that the parton content of virtual photons is logarithmically suppressed compared to real…
Two results in ep physics using HERA data are discussed: a measurement of the effective transverse parton momentum in the proton by studying the production of prompt-photons in photoproduction events in the ZEUS collaboration and…
Recent diffractive structure function measurements by the H1 and ZEUS experiments at HERA are reviewed. Various data sets, obtained using systematically different selection and reconstruction methods, are compared. NLO DGLAP QCD fits are…
An NLO QCD analysis on the HERA combined cross sections obtained from the measurements using the data up to the year 2000 at both the H1 and ZEUS collaborations provides significantly improved parton distribution functions. In 2007, HERA…
The structure functions of real and virtual photons are derived from cross section measurements of the reaction e^+e^ -> e^+e^- + hadrons at LEP. The reaction is studied at \sqrt{s} ~ 91 GeV with the L3 detector. One of the final state…
Recent results on the Deeply Virtual Compton Scattering (DVCS) and prompt photon productions from H1 and ZEUS experiments on the $ep$ collider HERA are presented. A new DVCS cross section measurements of the H1 Collaboration, for photon…