Study of taupair production at HERA
A study of events containing two tau leptons with high transverse momentum has been performed with the ZEUS detector at HERA, using a data sample corresponding to an integrated luminosity of 0.33 fb−1. The tau candidates were identified from their decays into electrons, muons or hadronic jets. The number of tau-pair candidates has been compared with the prediction from the Standard Model, where the largest contribution is expected from Bethe-Heitler processes. The total visible cross section was extracted. Standard Model expectations agree well with the measured distributions, also at high invariant mass of the tau pair.

title: Measurement of prompt photons with associated jets in photoproduction at HERA
abstract: The photoproduction of prompt photons, together with an accompanying jet, has been studied in ep collisions at a centre-of-mass energy of 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 77 pb-1. Cross sections were measured for the transverse energy of the photon and the jet larger than 5 and 6 GeV, respectively. The differential γ+jet cross sections were reconstructed as functions of the transverse energy, pseudorapidity and xγobs, the fraction of the incoming photon momentum taken by the photon-jet system. Predictions based on leading-logarithm parton-shower Monte Carlo models and next-to-leading-order (NLO) QCD generally underestimate the cross sections for the transverse energies of prompt photons below 7 GeV, while the kT-factorisation QCD calculation agrees with the data better. When the minimum transverse energy of prompt photons is increased to 7 GeV, both NLO QCD and the kT-factorisation calculations are in good agreement with the data.

title: Measurement of isolated photons accompanied by jets in deep inelastic ep scattering
abstract: The production of isolated high-energy photons accompanied by jets has been measured in deep inelastic ep scattering with the ZEUS detector at HERA, using an integrated luminosity of 326pb -1 . Measurements were made for exchanged photon virtualities, Q 2 , in the range 10 to 350GeV 2 . The photons were measured in the transverse-energy and pseudorapidity ranges 4 γ jet <1.8. Differential cross sections are presented as functions of these quantities. Perturbative QCD predictions give a reasonable description of the shape of the measured cross sections over most of the kinematic range, but the absolute normalisation is typically in disagreement by 20-30%.

title: Measurement of azimuthal asymmetries in neutral current deep inelastic scattering at HERA
abstract: The distribution of the azimuthal angle of charged and neutral hadrons relative to the lepton plane has been studied for neutral current deep inelastic ep scattering using an integrated luminosity of 45 pb-1 taken with the ZEUS detector. The kinematic range is 100<Q2<8000 GeV2, 0.2<y<0.8 and 0.01<x<0.1 where Q2 is the virtuality of the exchanged boson, y is the inelasticity and x is the Bjorken variable. The measurements were made in the hadronic centre-of-mass system. The analysis exploits the energy-flow method, which allows the measurement to be made over a larger range of pseudorapidity compared to previous results. The dependence of the moments of the azimuthal distributions on the pseudorapidity and minimum transverse energy of the final-state hadrons are presented. Although the predictions from next-to-leading-order QCD describe the data better than do the Monte Carlo models incorporating leading-logarithm parton showers, they still fail to describe the magnitude of the asymmetries. This suggests that higher-order calculations may be necessary to describe these data.

title: The spectrometer system for measuring ZEUS luminosity at HERA
abstract: The upgrade of the HERA accelerator has provided much increased collider luminosity. In turn, the improvements have necessitated a new design for the ZEUS luminosity measurements. The intense synchrotron radiation field, as well as the high probability of a bremsstrahlung photon in each bunch crossing, posed new experimental constraints. In this report, we describe how these challenges were met with the ZEUS luminosity spectrometer system. The design, testing and commissioning of the device are described, and the results from the initial operational experience are reported.

title: Measurement of charm fragmentation ratios and fractions in photoproduction at HERA
abstract: The production of D, D, D, D s and Λ + c charm hadrons and their antiparticles in ep scattering at HERA was measured with the ZEUS detector using an integrated luminosity of 79 pb. The measurement has been performed in the photoproduction regime with the exchanged-photon virtuality Q < 1 GeV and for photon-proton centre-of-mass energies in the range 130 < W < 300 GeV. The charm hadrons were reconstructed in the range of transverse momentum pT (D, Λc) > 3.8 GeV and pseudorapidity |η(D, Λc)| < 1.6. The production cross sections were used to determine the ratio of neutral and charged D-meson production rates, Ru/d, the strangeness-suppression factor, γs, and the fraction of charged D mesons produced in a vector state, P d v . The measured Ru/d and γs values agree with those obtained in deep inelastic scattering and in ee annihilations. The measured P d v value is smaller than, but consistent with, the previous measurements. The fractions of c quarks hadronising as a particular charm hadron, f(c → D, Λc), were derived in the given kinematic range. The measured open-charm fragmentation fractions are consistent with previous results, although the measured f(c → D) is smaller and f(c → Λc ) is larger than those obtained in ee annihilations. These results generally support the hypothesis that fragmentation proceeds independently of the hard sub-process. The ZEUS Collaboration S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, J. Repond, R. Yoshida Argonne National Laboratory, Argonne, Illinois 60439-4815, USA n M.C.K. Mattingly Andrews University, Berrien Springs, Michigan 49104-0380, USA N. Pavel, A.G. Yagües Molina Institut für Physik der Humboldt-Universität zu Berlin, Berlin, Germany P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, A. Margotti, A. Montanari, R. Nania, F. Palmonari, A. Pesci, A. Polini, L. Rinaldi, G. Sartorelli, A. Zichichi University and INFN Bologna, Bologna, Italy e G. Aghuzumtsyan, D. Bartsch, I. Brock, S. Goers, H. Hartmann, E. Hilger, P. Irrgang, H.-P. Jakob, O.M. Kind, U. Meyer, E. Paul, J. Rautenberg, R. Renner, M. Wang, M. Wlasenko Physikalisches Institut der Universität Bonn, Bonn, Germany b D.S. Bailey, N.H. Brook, J.E. Cole, G.P. Heath, T. Namsoo, S. Robins H.H. Wills Physics Laboratory, University of Bristol, Bristol, United Kingdom m M. Capua, S. Fazio, A. Mastroberardino, M. Schioppa, G. Susinno, E. Tassi Calabria University, Physics Department and INFN, Cosenza, Italy e J.Y. Kim, K.J. Ma Chonnam National University, Kwangju, South Korea g M. Helbich, Y. Ning, Z. Ren, W.B. Schmidke, F. Sciulli Nevis Laboratories, Columbia University, Irvington on Hudson, New York 10027 o J. Chwastowski, A. Eskreys, J. Figiel, A. Galas, M. Gil, K. Olkiewicz, P. Stopa, D. Szuba, L. Zawiejski The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland i L. Adamczyk, T. Bo ld, I. Grabowska-Bo ld, D. Kisielewska, J. Lukasik, M. Przybycień, L. Suszycki, J. Szuba Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Cracow, Poland p A. Kotański, W. S lomiński Department of Physics, Jagellonian University, Cracow, Poland

title: Measurement of the final states omega pi0, rho eta, and rho eta prime from psi (2S) electromagnetic decays and e+e- annihilations
abstract: Cross sections and form factors for $\ee \to \wpi$, $\rho\eta$, and $\rho\etap$ at center of mass energies of 3.650, 3.686, and 3.773 GeV are measured using data samples collected with the BESII detector at the BEPC. Also, the branching fractions of $\psi(2S) \rar \wpi$, $\rho\eta$, and $\rho\etap$ are determined to be $(1.87^{+0.68}_{-0.62}\pm0.28)\times 10^{-5}$, $(1.78^{+0.67}_{-0.62}\pm0.17)\times 10^{-5}$, and $(1.87^{+1.64}_{-1.11}\pm0.33)\times10^{-5}$, respectively.

title: Systematic calculation of fine structure in the α decay of deformed nuclei
abstract: We perform an extensive investigation on the a decay of well-deformed even-even nuclei by using the coupled-channel Schrodinger equation with outgoing wave boundary conditions. The internal effect of daughter states is taken into account in dealing with the interaction matrix and the α-cluster formation. In contrast to the traditional α-decay theories, the five-channel microscopic calculations of this work well reproduce the available experimental data concerning α-decay half-lives and fine structures. Some predictions on the fine structure are made for superheavy nuclei. Moreover, the sensitivity of the results to the model quantities is discussed in detail.

title: New perspective on complex cluster radioactivity of heavy nuclei
abstract: Experimental data of complex cluster radioactivity () are systematically analyzed and investigated with different models. The half-lives of cluster radioactivity are well reproduced by a new formula between half-lives and decay energies and by a microscopic density-dependent cluster model with the renormalized M3Y nucleon-nucleon interaction. The formula can be considered as a natural extension of both the Geiger-Nuttall law and the Viola-Seaborg formula from simple {alpha} decay to complex cluster radioactivity where different kinds of clusters are emitted. It is useful for experimentalists to analyze the data of cluster radioactivity. A new linear relationship between the decay energy of cluster radioactivity and the number of {alpha} particles in the cluster is found where the increase of decay energy for an extra {alpha} particle is between 15 and 17 MeV. The possible physics behind this new linear relationship is discussed.

title: Effect of final state interactions on particle production in $d$+Au collisions at RHIC
abstract: We show that particle species dependence of enhanced hadron production at intermediate transverse momentum ( pT ) for d+Au collisions at RHIC can be understood in terms of the hadronic res atterings in the final state. A multiphase transport mod el (AMPT) with two different hadronization mechanisms: string fragmentation or p arton coalescence, is used in our study. When the hadrons are formed from string fragmentation, the subse quent hadronic rescatterings will result in particle mass d ependence of nuclear modification factor RCP, which is consistent with the present experimental data. On the other hand, in the framework of parton coalescence, the mass dependence disappears and t he strangeness plays an important role. Both mechanisms fai led to reproduce thepT dependence of RCP of pion, indicating that initial-state e ffects might be also important in such collisions.

title: Systematic study of charge form factors of elastic electron-nucleus scattering with the relativistic eikonal approximation
abstract: We systematically investigate the elastic electron scattering on both stable and unstable nuclei with the relativistic eikonal approximation, where the charge density distributions of nuclei are from the self-consistent relativistic mean field model. Calculations show that the relativistic eikonal approximation can reproduce the experimental data of electron scattering on nuclei ranging from the light region, such as {sup 12}C, to the heavy region, such as {sup 208}Pb. This is the systematic test of the relativistic eikonal approximation for elastic electron scattering for both light and heavy nuclei. With this method, further studies are made of the variation of charge form factors along isotopic chains and the sensitivity of charge form factors to the changes of charge distribution. For isotopic chains with Z = 20 and 28, we find that the charge form factors vary significantly with neutron number. The charge form factors shift outward and downward when the target nucleus moves from the neutron-rich region to the proton-rich region along the isotopic chain. The significant shift shows that the charge form factor is very sensitive to a change of neutron number. If the isotopic shifts of the charge form factor are measured on the next-generation electron-nucleus collider (at RIKEN and more » GSI), the charge size and charge distribution can be determined for unstable nuclei. The calculations will provide a reference for future experiments. « less