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Abstract:

The production of excited charm, D 1(2420)⁰ and D 2 ^* (2460)⁰, and charm-strange, D s1(2536)^±, mesons in ep collisions was measured with the ZEUS detector at HERA using an integrated luminosity of 126 pb ^-1. Masses, widths and helicity parameters were determined. The measured yields were converted to the rates of c quarks hadronising as a given excited charm meson and to the ratios of the dominant D 2 ^* (2460)⁰ and D s1(2536) ^± branching fractions. A search for the radially excited charm meson, D ^*(2640)^±, was also performed. The results are compared with those measured previously and with theoretical expectations. © 2009 Springer-Verlag / Società Italiana di Fisica.

Abstract:

A search for events with an isolated high-energy lepton and large missing transverse momentum has been performed with the ZEUS detector at HERA using a total integrated luminosity of 504 pb^-1. The results agree well with Standard Model predictions. The cross section for production of single W bosons in electron-proton collisions with unpolarised electrons is measured to be 0.89-0.22^+0.25 (stat.) ± 0.10 (syst.) pb. © 2009 Elsevier B.V.

Abstract:

Deeply virtual Compton scattering, γ*p→γp has been measured in e⁺p collisions at HERA with the ZEUS detector using an integrated luminosity of 61.1 pb^-1. Cross sections are presented as a function of the photon virtuality, Q², and photon-proton centre-of-mass energy, W, for a wide region of the phase space, Q² > 1.5GeV² and 40 < W < 170GeV. A subsample of events in which the scattered proton is measured in the leading proton spectrometer, corresponding to an integrated luminosity of 31.3 pb^-1, is used for the first direct measurement of the differential cross section as a function of t, where t is the square of the four-momentum transfer at the proton vertex. © SISSA 2009.

Abstract:

The semi-inclusive reaction e+p→e+Xp was studied with the ZEUS detector at HERA with an integrated luminosity of 12.8 pb -1. The final-state proton, which was detected with the ZEUS leading proton spectrometer, carried a large fraction of the incoming proton energy, xL > 0.32, and its transverse momentum squared satisfied p 2T < 0.5GeV2; the exchanged photon virtuality, Q2, was greater than 3GeV2 and the range of the masses of the photon-proton system was 45 < W < 225GeV. The leading proton production cross section and rates are presented as a function of xL, p2 T , Q2 and the Bjorken scaling variable, x. © SISSA 2009.