2,464 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

    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