Related papers: Survey of present data on photon structure functio…
The feasibility of an experimental determination of the parton distributions of virtual photons at high energy $ep$ colliders is studied in the context of the DESY-HERA collider. Recently proposed parton densities of virtual photons are…
We present results from NLO QCD calculations on the production of jets in ep collisions at HERA in a continuous range of photon virtuality Q^2. Special attention is given to the collinear singularities from the virtual photon and the…
We discuss the inclusive jet production at HERA in the next-to-leading logarithm approximation. Theoretical uncertainties are considered in some details. We show the importance of the jet rapidity distribution to constrain the parton…
Recent results from HERA are presented. The main reviewed subjects are polarized DIS cross sections, parton density determination, diffractive PDFs, multi-jet production and searches for physics beyond the Standard Model.
High energy multiparticle photoproduction off nuclear targets is studied. The photon is assumed to interact in direct scattering processes or as a resolved $q\bar{q}$-state according to the Generalized Vector Dominance Model. In the…
In this talk I present a summary of some of the discussions at the conference on various topics in Photon physics, selected with a view to give a theorist's perspective, of the current status and future prospects, of the developments in the…
Data from the HERA collider experiments, H1 and ZEUS, have been fundamental to the rapid recent development of our understanding of the partonic composition of the proton and of QCD. This report focuses on inclusive measurements of neutral…
We re\,examine the theory of hadronic photon-nucleon interactions at the quark-gluon level. The possibility of multiple parton collisions in a single photon-nucleon collision requires an eikonal treatment of the high-energy scattering…
We discuss how the dijet azimuthal correlations in DIS and real photoproduction at HERA probe the differential (unintegrated) gluon distribution in the proton. We find a strong dependence of the azimuthal correlation pattern on Bjorken-$x$,…
The triple-differential dijet cross-section, d^3 sigma_{ep}/dQ2 dE_t2 dxgjets, is measured with the H1 detector at HERA as a function of the photon virtuality Q^2, the fraction of the photon's momentum carried by the parton entering the…
Interactions of the type ep -> eXY are studied, where the component X of the hadronic final state contains two jets and is well separated in rapidity from a leading baryonic system Y. Analyses are performed of both resolved and direct…
We argue that the process $pp \to (\text{jet} \gamma)X$, for which a photon is observed inside a fully reconstructed jet and is treated as part of the jet, offers new probes of the so far little known fragmentation functions for photons. We…
The high precision and large kinematic coverage of the data from the HERA-I running period (1994-2000) have already allowed precise extractions of proton parton distribution functions. The HERA-II running program is now underway and is…
Photoproduction at HERA is studied in $ep$ collisions, with the ZEUS detector, for $\gamma p$ centre-of-mass energies ranging from 130-270 GeV. A sample of events with two high-$p_T$ jets ($p_T > 6$ GeV, $\eta <1.6$) and a third cluster in…
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 <…
In this thesis the polarized and unpolarized photon distributions of the nucleon (proton, neutron) $(\Delta)\gamma^N$, evaluated in the equivalent photon approximation (EPA), are computed theoretically and the possibility of their…
A summary of recent results reported in the Structure Functions and Low-x working group at the DIS 2009 Workshop is given. Recent measurements of deep inelastic scattering cross sections and structure functions at HERA and of proton…
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…
We re-examine the current state of the art for the calculation of photon-initiated processes at the LHC, as formulated in terms of a photon PDF in the proton that may be determined rather precisely from the known proton structure functions.…
Recent results on diffraction at HERA, from the H1 and ZEUS Collaborations, and at Tevatron, from the CDF and D0 Collaborations, are reviewed. The measurement of the diffractive structure function at HERA is presented, and the pomeron…