Measurement of D^{*\pm} meson production and determination of F_2^{ccbar} at low Q2 in deep-inelastic scattering at HERA

Inclusive production of D ∗ mesons in deep-inelastic ep scattering at HERA is studied in the range 51.25 GeV and |η(D ∗)|<1.8. The data sample corresponds to an integrated luminosity of 348 pb−1 collected with the H1 detector. Single and double differential cross sections are measured and the charm contribution F2cc to the proton structure function F 2 is determined. The results are compared to perturbative QCD predictions at next-to-leading order implementing different schemes for the charm mass treatment and with Monte Carlo models based on leading order matrix elements with parton showers

A global analysis of diffractive events at HERA

We extract diffractive parton distribution functions (DPDFs) and diffractive structure functions from the most recent H1 and ZEUS diffractive DIS data obtained by various methods. We consider Pomeron as an object with parton distribution function, evolving according to the next-to-leading order (NLO) DGLAP equations within the framework of the `Fixed Flavour Number Scheme' (FFNS). Having performed a global fit analysis, we achieve a very good description of all available measurements by introducing a new set of quark distribution form for the Pomeron. We predict longitudinal and charm proton diffractive structure function as well. Our results are compared with other analysis from the literature.Comment: 28 Pages, 15 Figures, 3 Table

The dual parametrization for gluon GPDs

We consider the application of the dual parametrization for the case of gluon GPDs in the nucleon. This provides opportunities for the more flexible modeling unpolarized gluon GPDs in a nucleon which in particular contain the invaluable information on the fraction of nucleon spin carried by gluons. We perform the generalization of Abel transform tomography approach for the case of gluons. We also discuss the skewness effect in the framework of the dual parametrization. We strongly suggest to employ the fitting strategies based on the dual parametrization to extract the information on GPDs from the experimental data.Comment: 37 pages, 2 figure

Measurement of dijet production in diffractive deep-inelastic scattering with a leading proton at HERA

The cross section of diffractive deep-inelastic scattering ep→eXp is measured, where the system X contains at least two jets and the leading final state proton is detected in the H1 Forward Proton Spectrometer. The measurement is performed for fractional proton longitudinal momentum loss x ℙ<0.1 and covers the range 0.1<|t|<0.7 GeV2 in squared four-momentum transfer at the proton vertex and 4<Q 2<110 GeV2 in photon virtuality. The differential cross sections extrapolated to |t|<1 GeV2 are in agreement with next-to-leading order QCD predictions based on diffractive parton distribution functions extracted from measurements of inclusive and dijet cross sections in diffractive deep-inelastic scattering. The data are also compared with leading order Monte Carlo models.ISSN:1434-6044ISSN:1434-605

Search for squarks in R-parity violating supersymmetry in ep collisions at HERA

A search for squarks in R-parity violating supersymmetry is performed in e ± p collisions at HERA using the H1 detector. The full data sample taken at a centre-of-mass energy s√=319 GeV is used for the analysis, corresponding to an integrated luminosity of 255 pb−1 of e + p and 183 pb−1 of e − p collision data. The resonant production of squarks via a Yukawa coupling λ′ is considered, taking into account direct and indirect R-parity violating decay modes. Final states with jets and leptons are investigated. No evidence for squark production is found and mass dependent limits on λ′ are obtained in the framework of the Minimal Supersymmetric Standard Model and in the Minimal Supergravity Model. In the considered part of the parameter space, for a Yukawa coupling of electromagnetic strength λ′=0.3, squarks of all flavours are excluded up to masses of 275 GeV at 95% confidence level, with down-type squarks further excluded up to masses of 290 GeV.ISSN:1434-6044ISSN:1434-605

Jet production in ep collisions at low Q2 and determination of αs

The production of jets is studied in deep-inelastic e + p scattering at low negative four momentum transfer squared 5<Q 2<100 GeV2 and at inelasticity 0.2<y<0.7 using data recorded by the H1 detector at HERA in the years 1999 and 2000, corresponding to an integrated luminosity of 43.5 pb−1. Inclusive jet, 2-jet and 3-jet cross sections as well as the ratio of 3-jet to 2-jet cross sections are measured as a function of Q 2 and jet transverse momentum. The 2-jet cross section is also measured as a function of the proton momentum fraction ξ. The measurements are well described by perturbative quantum chromodynamics at next-to-leading order corrected for hadronisation effects and are subsequently used to extract the strong coupling α s .ISSN:1434-6044ISSN:1434-605

Measurement of photon production in the very forward direction in deep-inelastic scattering at HERA

The production of photons at very small angles with respect to the proton beam direction is studied in deep-inelastic positron–proton scattering at HERA. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 126 pb−1. The analysis covers the range of negative four momentum transfer squared at the positron vertex 67.9 as a function of its transverse momentum pleadT and longitudinal momentum fraction of the incoming proton xleadL. In addition, the cross sections are studied as a function of the sum of the longitudinal momentum fraction xsumL of all photons in the pseudorapidity range η>7.9. The cross sections are normalised to the inclusive deep-inelastic scattering cross section and compared to the predictions of models of deep-inelastic scattering and models of the hadronic interactions of high energy cosmic rays.ISSN:1434-6044ISSN:1434-605

Erratum to: Determination of the integrated luminosity at HERA using elastic QED compton events

ISSN:1434-6044ISSN:1434-605