A. Keramidas

Measurement of the charm fragmentation function in D* photoproduction at HERA

The charm fragmentation function has been measured in D* photoproduction with the ZEUS detector at HERA using an integrated luminosity of 120 pb(-1). The fragmentation function is measured versus z = (E + p(parallel to))(D)* / 2E(jet), where E is the energy of the D* meson and p(parallel to) is the longitudinal momentum of the D* meson relative to the axis of the associated jet of energy E-jet. Jets were reconstructed using the k(T) clustering algorithm and required to have transverse energy larger than 9GeV. The D* meson associated with the jet was required to have a transverse momentum larger than 2GeV. The measured function is compared to different fragmentation models incorporated in leading-logarithm Monte Carlo simulations and in a next-to-leading-order QCD calculation. The free parameters in each fragmentation model are fitted to the data. The extracted parameters and the function itself are compared to measurements from e(+)e(-) experiments.

Dissociation of virtual photons in events with a leading proton at HERA

Abstract.The ZEUS detector has been used to study dissociation of virtual photons in events with a leading proton,

Measurement of beauty production in deep inelastic scattering at HERA

\gamma^{*} p \to X p

Substructure dependence of jet cross sections at HERA and determination of alpha s

, in e + p collisions at HERA. The data cover photon virtualities in two ranges, 0.03 < Q2 < 0.60 GeV2 and 2 < Q2 < 100 GeV2, with MX > 1.5 GeV, where MX is the mass of the hadronic final state, X. Events were required to have a leading proton, detected in the ZEUS leading proton spectrometer, carrying at least 90% of the incoming proton energy. The cross section is presented as a function of t, the squared four-momentum transfer at the proton vertex,

Search for a narrow charmed baryonic state decaying to D ∗± p ∓ in ep collisions at HERA

\Phi

Inclusive-jet cross sections in NC DIS at HERA and a comparison of the k(T), anti-k(T) and SIScone jet algorithms

, the azimuthal angle between the positron scattering plane and the proton scattering plane, and Q2. The data are presented in terms of the diffractive structure function,

Search for events with an isolated lepton and missing transverse momentum and a measurement of W production at HERA

F_2^{\smash[t]{D(3)}}

Measurement of J/psi photoproduction at large momentum transfer at HERA

. A next-to-leading-order QCD fit to the higher-Q2 data set and to previously published diffractive charm production data is presented.

Measurement of D+ and Λc+ production in deep inelastic scattering at HERA

The beauty production cross section for deep inelastic scattering events with at least one hard jet in the Breit frame together with a muon has been measured, for photon virtualities Q^2>2 GeV^2, with the ZEUS detector at HERA using integrated luminosity of 72 pb^-1. The total visible cross section is sigma_b-bbar (ep ->e jet mu X) = 40.9 +- 5.7 (stat.) +6.0 -4.4 (syst.) pb. The next-to-leading order QCD prediction lies about 2.5 standard deviations below the data. The differential cross sections are in general consistent with the NLO QCD predictions; however at low values of Q^2, Bjorken x, and muon transverse momentum, and high values of jet transverse energy and muon pseudorapidity, the prediction is about two standard deviations below the data.

Measurement of high-Q 2 charged current deep inelastic scattering cross sections with a longitudinally polarised positron beam at HERA

Jet substructure and differential cross sections for jets produced in the photoproduction and deep inelastic ep scattering regimes have been measured with the ZEUS detector at HERA using an integrated luminosity of 82.2 pb-1. The substructure of jets has been studied in terms of the jet shape and subjet multiplicity for jets with transverse energies Et(jet) > 17 GeV. The data are well described by the QCD calculations. The jet shape and subjet multiplicity are used to tag gluon- and quark-initiated jets. Jet cross sections as functions of Et(jet), jet pseudorapidity, the jet-jet scattering angle, dijet invariant mass and the fraction of the photon energy carried by the dijet system are presented for gluon- and quark-tagged jets. The data exhibit the behaviour expected from the underlying parton dynamics. A value of alphas(Mz) of alphas(Mz) = 0.1176 +-0.0009(stat.) -0.0026 +0.0009 (exp.) -0.0072 +0.0091 (th.) was extracted from the measurements of jet shapes in deep inelastic scattering. Comment: 67 pages, 17 figures, 24 tables