2,719 research outputs found

    Combined HERA Deep Inelastic Scattering Data and NLO QCD Fits

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    Previously published data on inclusive neutral and charged current e+p and e-p deep inelastic scattering from HERA have been combined. The new, model-independent method of combining the measured cross sections takes full account of correlated systematics in a coherent way, leading to significantly reduced uncertainties in the combined measurement across the (x, Q^2) plane. The combined cross section data have been used as the sole input for a new next-to-leading order QCD fit to extract the parton distribution functions (PDFs) of the proton. The PDFs extracted have greatly reduced experimental uncertainties, compared to separate QCD analyses on data from H1 and ZEUS. Model uncertainties, including those arising from the parameterisation dependence, have also been carefully considered. The resulting HERA PDFs have impressive precision.Comment: 11 pages, 6 figures, prepared for the proceedings of the Ringberg Workshop on "New Trends in HERA Physics 2008", Ringberg Castle, Tegernsee, Oct 5-10, 200

    Jets in Deep Inelastic Scattering and High Energy Photoproduction at HERA

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    Recent results on jet production in neutral current deep inelastic scattering and high energy photoproduction at the HERA electron-proton-collider are briefly reviewed. The results are compared to QCD expectations in NLO and αs\alpha_s determinations using these data are summarized.Comment: 12 pages, 10 figures, talk given at the 9th Adriatic Meeting "Particle Physics and the Universe" in Dubrovnik/Croatia, 4.-24.9.200

    NRQCD Factorization and Quarkonium Production at Hadron-Hadron and ep Colliders

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    I review the NRQCD factorization approach for quarkonium production and compare its predictions with measurements in hadron-hadron and ep collisions.Comment: 6 pages, contribution to the proceedings of Charm 2010, IHEP, Beijing, October 21-24, 201

    Vector Meson Production in the Golec-Biernat Wuesthoff Model

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    We apply the Golec-Biernat Wuesthoff model in the calculation of vector meson photo- and electroproduction. Starting from very simple non-relativistic wave functions we show that the model provides a good description of J/ΨJ/\Psi cross sections in wide Q2Q^2 and WW ranges. For the light mesons one obtains the approximately correct WW dependence and ratio of longitudinal to transverse cross sections, although in this case the normalization, affected mainly by the wave function employed, is not in good agreement with data

    MICROMEGAS chambers for hadronic calorimetry at a future linear collider

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    Prototypes of MICROMEGAS chambers, using bulk technology and analog readout, with 1x1cm2 readout segmentation have been built and tested. Measurements in Ar/iC4H10 (95/5) and Ar/CO2 (80/20) are reported. The dependency of the prototypes gas gain versus pressure, gas temperature and amplification gap thickness variations has been measured with an 55Fe source and a method for temperature and pressure correction of data is presented. A stack of four chambers has been tested in 200GeV/c and 7GeV/c muon and pion beams respectively. Measurements of response uniformity, detection efficiency and hit multiplicity are reported. A bulk MICROMEGAS prototype with embedded digital readout electronics has been assembled and tested. The chamber layout and first results are presented
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