7,285 research outputs found

    The virtual photon structure at HERA

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    An overview is given of the ongoing measurement at HERA of the parton structure of the photon, as a function of its virtuality. Preliminary ZEUS results show disagreement with an NLO QCD calculation.Comment: To appear in Proc. International Conference on the Structure and Interactions of the Photon, Frascati, April 200

    Detection of new states using forward proton tagging at the LHC

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    This talk summarises the ongoing proposals to upgrade the ATLAS and CMS detectors by the installation of forward silicon detector systems close to the beam line at distances of approximately 220 m and 420 m from the respective Interaction Points. The physics motivation is outlined, with emphasis on detection of Higgs and Supersymmetric states, and some of the aspects of the apparatus and its performance are briefly described.Comment: For ICHEP XXXIV Conference Proceedings. 4 pages. v2 has updated refs and minor corrections. v3 has cosmetic layout change

    Prompt photon, Drell-Yan and Bethe-Heitler processes in hard photoproduction

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    We present prospects and requirements for the study at HERA of hard photon processes which generate high pTp_T photons in the final state, and processes which generate Drell-Yan lepton pairs.Comment: 6 pages, 3 embedded figures. To appear in the proceedings of the workshop "Future physics at HERA

    Resonance Contributions to η\eta Photoproduction on Protons Found Using Dispersion Relations and an Isobar Model

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    The contributions of the resonances D13(1520)D_{13}(1520), S11(1535)S_{11}(1535), S11(1650)S_{11}(1650), D15(1675)D_{15}(1675), F15(1680)F_{15}(1680), D13(1700)D_{13}(1700), P11(1710)P_{11}(1710), P13(1720)P_{13}(1720) to γpηp\gamma p\to \eta p are found from the data on cross sections, beam and target asymmetries using two approaches: fixed-t dispersion relations and an isobar model. Utilization of the two approaches and comparison of the results obtained with different parametrizations of the resonance contributions allowed us to make conclusions about the model-dependence of these contributions. We conclude that the results for the contributions of the resonances D13(1520)D_{13}(1520), S11(1535)S_{11}(1535), F15(1680)F_{15}(1680) to corresponding multipole amplitudes are stable. With this the results for D13(1520)D_{13}(1520) and F15(1680)F_{15}(1680), combined with their PDG photoexcitation helicity amplitudes, allowed us to find the branching ratios Br(D13(1520)ηN)=0.05±0.02Br (D_{13}(1520)\to \eta N)=0.05\pm 0.02%, Br(F15(1680)ηN)=0.16±0.04Br (F_{15}(1680)\to \eta N)=0.16\pm0.04% which have significantly better accuracy than the PDG data. The total Breit-Wigner width of the S11(1535)S_{11}(1535) is model-dependent, we have obtained Γ(S11(1520))=142MeV\Gamma (S_{11}(1520))=142 MeV and 195MeV195 MeV using dispersion relations and the isobar model, respectively. The results for the S11(1650)S_{11}(1650), D15(1675)D_{15}(1675), P11(1710)P_{11}(1710), P13(1720)P_{13}(1720) are model dependent, only the signs and orders of magnitude of their contributions to multipole amplitudes are determined. The results for the D13(1700)D_{13}(1700) are strongly model-dependent.Comment: 26 pages, 6 figure

    Cognitive enhancing effects of voluntary exercise, caloric restriction and environmental enrichment: A role for adult hippocampal neurogenesis and pattern separation?

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    Several behavioural interventions, such as physical exercise, dietary restriction, and enriched environments are associated with both improved cognition and increased adult hippocampal neurogenesis. Whether the learning and memory improvements associated with these interventions are causally dependent on the upregulated neurogenesis has not yet been conclusively determined. However, with the accumulating evidence of a role for adult-born hippocampal neurons in spatial pattern separation, it is possible that the improvements in learning and memory result, at least in part, from an improvement in pattern separation. The following review focuses on three major behavioural manipulations associated with cognitive enhancement: voluntary exercise, caloric restriction, and environmental enrichment (including learning), and how increased neurogenesis may contribute to the enhancement by improving pattern separation.The authors would like to acknowledge financial contribution from the following funding sources: the Innovative Medicine Initiative Joint Undertaking under grant agreement no. 115008, of which resources are composed of a European Federation of Pharmaceutical Industries and Associations in-kind contribution and financial contribution from the European Union's Seventh Framework Programme (FP7/2007–2013); The Wellcome Trust/Medical Research Council (089703/Z/09/Z) and the Biotechnology and Biological Sciences Research Council (grant BB/G019002/1). C.A.O. received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 603016. B.A.K. was supported by Gates Cambridge.This is the author accepted manuscript. The final version is available from Elsevier at http://www.sciencedirect.com/science/article/pii/S235215461500087X

    Photoproduction of pions and properties of baryon resonances from a Bonn-Gatchina partial wave analysis

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    Masses, widths and photocouplings of baryon resonances are determined in a coupled-channel partial wave analysis of a large variety of data. The Bonn-Gatchina partial wave formalism is extended to include a decomposition of t- and u-exchange amplitudes into individual partial waves. The multipole transition amplitudes for γppπ0\gamma p\to p\pi^0 and γpnπ+\gamma p\to n\pi^+ are given and compared to results from other analyses.Comment: 18 pages, 14 figure

    Sparticle masses in deflected mirage mediation

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    We discuss the sparticle mass patterns that can be realized in deflected mirage mediation scenario of supersymmetry breaking, in which the moduli, anomaly, and gauge mediations all contribute to the MSSM soft parameters. Analytic expression of low energy soft parameters and also the sfermion mass sum rules are derived, which can be used to interpret the experimentally measured sparticle masses within the framework of the most general mixed moduli-gauge-anomaly mediation. Phenomenological aspects of some specific examples are also discussed.Comment: 43 pages, 17 figures, references adde
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