396 research outputs found

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

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    Measurements of the cross sections for charged current deep inelastic scattering in e+p collisions with a longitudinally polarised positron beam are presented. The measurements are based on a data sample with an integrated luminosity of 132 pb-1 collected with the ZEUS detector at HERA at a centre-of-mass energy of 318 GeV. The total cross section is presented at positive and negative values of the longitudinal polarisation of the positron beams. The single-differential cross-sections dσ/dQ2, dσ/dx and dσ/dy are presented for Q2>200 GeV2. The reduced cross-section σ̃ is presented in the kinematic range 200<Q2<60000 GeV2 and 0.006<x<0.562. The measurements agree well with the predictions of the Standard Model. The results are used to determine a lower limit on the mass of a hypothetical right-handed W boson. © 2010 The Author(s)

    Combined inclusive diffractive cross sections measured with forward proton spectrometers in deep inelastic ep scattering at HERA

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    A combination of the inclusive diffractive cross section measurements made by the H1 and ZEUS Collaborations at HERA is presented. The analysis uses samples of diffractive deep inelastic ep scattering data at a centre-of-mass energy √s= 318 Gev where leading protons are detected by dedicated spectrometers. Correlations of systematic uncertainties are taken into account, resulting in an improved precision of the cross section measurement which reaches 6 % for the most precise points. The combined data cover the range 2.5 < Q 2 < 200 GeV 2 in photon virtuality, 0.00035 < xP < 0.09 in proton fractional momentum loss, 0.09 <{pipe}t{pipe}< 0.55 GeV 2 in squared four-momentum transfer at the proton vertex and 0.0018 < β <0.816 in β=x/xP, where x is the Bjorken scaling variable. © 2012 The Author(s).0H1 and ZEUS CollaborationsSCOPUS: ar.jinfo:eu-repo/semantics/publishe

    Photoproduction of D*(+/-) mesons associated with a leading neutron

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    The photoproduction of D*(+/-)(2010) mesons associated with a leading neutron has been observed with the ZEUS detector in ep collisions at HERA using an integrated luminosity of 80 pb(-1). The neutron carries a large fraction, x(L) gt 0.2, of the incoming proton beam energy and is detected at very small production angles, theta(n) lt 0.8 mrad, an indication of peripheral scattering. The D* meson is centrally produced with pseudorapidity \eta\ lt 1.5, and has a transverse momentum p(T) gt 1.9 GeV, which is large compared to the average transverse momentum of the neutron of 0.22 GeV The ratio of neutron-tagged to inclusive D* production is 8.85 +/- 0.93(stat.)(- 0.61)(+0.48)(syst.)% in the photon-proton center-of-mass energy range 130 lt W lt 280 Gev The data suggest that the presence of a hard scale enhances the fraction of events with a leading neutron in the final state
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