Related papers: Partonic structure of $\gamma_L^*$ in hard collisi…
We explore the relevance of extending the concept of the structure to the longitudinally polarized virtual photon involved in hard collisions. We show that for moderate photon virtualities and in the kinematical region accessible in current…
The manifestations of QCD effects on quark and gluon distribution functions of longitudinally polarized virtual photons involved in hard collisions are investigated. It is shown that for moderate photon virtualities and in the kinematical…
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…
Interactions of virtual photons are analyzed in terms of their parton distribution functions. It is shown that the concept of parton distribution functions is phenomenologically very useful even for highly virtual photonds involved in hard…
At $e^+e^-$ and $ep$ colliders, the large fluxes of almost on-shell photons accompanying the lepton beams lead to the photoproduction of jets. As the centre-of-mass energy is increased, regions of smaller $x$ in the parton densities are…
The structure of real and virtual photons has been studied in ep collisions at HERA using dijet production. Measurements of differential dijet cross sections as function of the fraction of photon's momentum invested in the dijet system are…
We study various conceivable photoproduction reactions in a polarized ep collider mode of HERA with respect to their sensitivity to the proton's polarized gluon distribution. A special emphasis is put on the `resolved' part of the cross…
Triple differential dijet cross-sections in e p interactions measured with the H1 and ZEUS detectors at HERA are presented. The data are compared to Monte Carlo simulations which differ in their assumptions about photon structure and parton…
Di-jet photoproduction in polarized ep collisions at HERA is studied as a possible tool to determine the parton content of circularly polarized photons. The concept of the `effective parton density' approximation is extended to the…
Results are given on the measurements of the hard diffractive interactions at HERA $ep$ collider. The structure of the diffractive exchange in terms of partons and the factorisation properties are discussed, in particular by comparing the…
New results reported at the Moriond-QCD 2003 conference from the experiments ALEPH, DELPHI, L3, and OPAL on the structure of the photon as well as heavy quark production in gammagamma collisions are presented. The hadronic structure of the…
Jet production in electron-proton collisions at HERA provides a unique testing ground for Quantum Chromodynamics (QCD). Apart from the determination of the strong coupling constant $\alpha_s$, ep jet data may especially be used to gain…
An overview of the latest results of the LEP collaborations on QCD measurements in photon-photon collisions is presented, including measurements of the total hadronic cross-section, the production of heavy quarks and dijets and the…
Present data on the partonic content of the photon from LEP, TRISTAN and HERA accelerators are reviewed and the essential aspects of the underlying ideas and methods are pointed out. Results of the unpolarized photon structure function F_2…
Since the start of HERA operation there has been considerable progress in the understanding of jet production in e p collisions. QCD calculations are now able to accommodate the hadronic structure of the virtual photon. The luminosities…
Measurements of di-jet production at HERA provide an important test of NLO QCD calculations. It is also a source of information about partonic content of the photon, complementary to the measurements in e+e- experiments. In this article we…
At HERA, the large flux of almost real photons accompanying the electron beam leads to the copious photoproduction of jets. Regions of small momentum fractions $x$ of the incoming particles are explored, where the density of partons is…
Interactions of virtual photons are analyzed in terms of photon structure. It is argued that the concept of parton distribution functions is phenomenologically very useful even for highly virtual photons involved in hard collisions. The…
Triple differential dijet cross-sections in electron proton interactions measured with the H1 detector at HERA are presented. The data are compared to Monte Carlo simulations based on the DGLAP and CCFM parton evolution schemes. Effects of…
Recent experimental results on the partonic structure of the photon and on the color singlet exchange in strong interaction processes are reviewed. At the LEP electron-positron and HERA lepton-proton colliders, complementary and consistent…