Related papers: Real and Virtual Photon Structure at HERA
Di-jet production is studied in collisions of quasi-real photons radiated by the LEP beams at e+e- centre-of-mass energies 161 and 172 GeV. The jets are reconstructed using a cone jet finding algorithm. The angular distributions of direct…
A survey is presented of the various processes measurable at HERA in which two photons are involved. Their current experimental status and future prospects are discussed.
Differential dijet cross sections in diffractive deep-inelastic scattering are measured with the H1 detector at HERA using an integrated luminosity of 51.5 pb-1. The selected events are of the type ep --> eXY, where the system X contains at…
Measurements of Deeply Virtual Compton Scattering (DVCS) are presented using data collected by the H1 and ZEUS experiments at HERA. The transition from a virtual photon to an on-shell particle is expected to necessitate the use of skewed…
The cross section of the diffractive process e^+p -> e^+Xp is measured at a centre-of-mass energy of 318 GeV, where the system X contains at least two jets and the leading final state proton p is detected in the H1 Very Forward Proton…
A review is given of the latest results on jet production and studies of event shape variables in deep inelastic scattering at HERA. Jet cross sections studies for inclusive jet and dijet events are presented and compared to next-to-leading…
The cross section for ep -> e b\bar{b} X in photoproduction is measured with the H1 detector at the ep-collider HERA. The decay channel b\bar{b} -> ee X' is selected by identifying the semi-electronic decays of the b-quarks. The total…
New results on the Deeply Virtual Compton Scattering process $\gamma^* p \to \gamma p$ (DVCS) from H1 experiment at the $e p$ collider HERA are presented, using data collected during the year 2004 and corresponding to an integrated…
The exclusive diffractive production of vector mesons and real photons in ep collisions has been studied at HERA in a wide kinematic range. Here we present the most recent experimental results together with a Regge-type model. We deduce the…
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 show that photoproduction cross sections recently measured by ZEUS and H-1 at HERA energies$^1$ are in agreement with our earlier prediction based on high-energy hadronic structure of the photon in the QCD minijet-type model$^2$. We…
Differential cross sections for inclusive dijet photoproduction on a virtual pion have been calculated in next-to-leading order QCD as a function of $E_T, \eta$, and $x_{\pi}$. The cross sections are compared with recent ZEUS data on…
Recent results on structure functions and parton distribution functions at HERA are presented. Results on the measurements of the structure functions F2, FL and F3 will be covered, as well as the results of the most recent QCD fits to…
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…
Two-jet production from the direct photon contribution at HERA is a sensitive measure of the small-$x$ gluon in the proton. We propose measurements of ratios of the jet cross-sections which will clearly distinguish between gluons with or…
A recent analysis of prompt-photon events in ZEUS has led to a new determination of the effective transverse parton momentum in the proton. The observation of deeply virtual Compton scattering by ZEUS and H1, including a first measurement…
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…
We present one- and two-jet inclusive cross sections for gamma*gamma scattering and virtual photoproduction in ep collisions. The hard cross sections are calculated in next-to-leading order QCD. Soft and collinear singularities are…
Di-jet producion is studied in collisions of quasi-real photons at e+e- centre- of-mass energies sqrt(s)ee from 189 to 209 GeV at LEP. The data were collected with the OPAL detector. Jets are reconstructed using an inclusive k_t clustering…
Recent results from the \emph{ep} collier HERA are presented. Inclusive dijet cross sections have been measured in neutral current deep inelastic scattering, for virtualities of the exchanged boson in the range $125 < Q^{2} < 20\,000\;…