Related papers: Factorisation breaking in diffractive dijet photop…
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…
We have calculated diffractive dijet production in deep-inelastic scattering (DIS) at low-Q^2 and next-to-leading order (NLO) of perturbative QCD, including contributions from direct and resolved photons. We study how the cross section…
The proton diffractive structure function $F_2^{D(3)}$ measured in the H1 and ZEUS experiments at HERA is analyzed in terms of both Regge phenomenology and perturbative QCD evolution. A new method determines the values of the Regge…
Measurements of charmed particle cross sections at HERA in the photoproduction and deep inelastic regimes are reviewed. The status of the comparison with perturbative QCD calculations is discussed.
The H1 and Zeus collaborations have measured the inclusive diffractive DIS cross section ep -> eXp and these measurements are in good agreement within a normalisation uncertainty. Diffractive parton density functions (DPDFs) have been…
Many important QCD tests with jets and prompt photons have been performed with the experiments H1 and ZEUS at the HERA ep collider. This contribution focuses on results from jet and prompt photon photoproduction. In particular, the concept…
Studies on the structure of the photon are presented by means of the extraction of a leading order effective parton distribution in the photon and measurements of inclusive jet differential cross sections in photoproduction. Measurements of…
We review topical results on diffractive processes from the experiments H1 and ZEUS at the HERA electron-proton collider. Emphasis is placed on the phenomenological and experimental consequences of the discoveries at HERA for the proposed…
Measurements of jet production in the photoproduction region at HERA are presented, which are sensitive to the underlying event structure. It is argued that in the photoproduction region a significant amount of multi-parton interactions in…
Inclusive charm meson production cross sections in the deep inelastic scattering and photoproduction regimes are compared with QCD leading and next-to-leading (NLO) calculations. The NLO predictions are significantly below the data in some…
Inclusive jet and multijet cross sections measured in ep collisions in different kinematic regions by the H1 and ZEUS experiments are shown. The measurements are used to extract the strong coupling alpha_s as a function of the scale and at…
We study the photoproduction of a D^{*+-} meson in association with a hadron jet at next-to-leading order in the parton model of QCD with non-perturbative fragmentation functions extracted from LEP1 data of e^+e^- annihilation. The…
The cross section for photoproduction of an isolated prompt photon in association with a jet is studied in Next-to-Leading Order. The kinematics are those appropriate for the DESY $ep$ collider HERA. The effects on the cross section of…
We extract diffractive parton densities from data on diffractive deep inelastic scattering (DIS) and on diffractive photoproduction of jets. We explore the results of several ansaetze for the functional form of the parton densities. Then 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…
Recent results on dijet production in deep-inelastic scattering from the H1 experiment at the ep-collider HERA are presented. Internal jet structure has been studied in terms of jet shapes and subjet multiplicities in the Breit frame. Both…
We perform a NLO QCD analysis of single-diffractive dijet production in proton-antiproton collisions. By comparing the ratio of single- and non-diffractive cross sections to data from the Tevatron, the rapidity-gap survival probability is…
We calculate the cross section of charm photoproduction at HERA collider in the framework of the kt-factorization QCD approach. Our analysis cover the inclusive charm production as well as charm and associated jet production processes. Both…
A review is given of the measurements of the hard diffractive interactions in recent years from two high-energy colliders, the HERA $ep$ collider and the Tevatron $p\bar{p}$ collider. The structure of the diffractive exchange in terms of…
In view of possible photoproduction studies in ultraperipheral heavy-ion collisions at the LHC, we briefly review the present theoretical understanding of photons and hard photoproduction processes at HERA, discussing the production of…