8,733 research outputs found

    Global Analysis of Fragmentation Functions for Protons and Charged Hadrons

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    We present new sets of fragmentation functions for protons and inclusive charged hadrons obtained in combined NLO QCD analyses of single-inclusive hadron production in electron-positron annihilation, proton-proton collisions, and deep-inelastic lepton-proton scattering. These analyses complement previous results for pion and kaon fragmentation functions with charge and flavor discrimination. The Lagrange multiplier technique is used to assess the uncertainties in the extraction of the new sets of fragmentation functions.Comment: 14 pages, 14 figure

    Evidence for polarization of gluons in the proton

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    We discuss the impact of recent high-statistics RHIC data on the determination of the gluon polarization in the proton in the context of a global QCD analysis of polarized parton distributions. We find clear evidence for a non-vanishing polarization of gluons in the region of momentum fraction and at the scales mostly probed by the data. Although information from low momentum fractions is presently lacking, this finding is suggestive of a significant contribution of gluon spin to the proton spin, thereby limiting the amount of orbital angular momentum required to balance the proton spin budget.Comment: 5 pages, 5 eps figure

    Global Analysis of Nuclear PDFs

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    We present a new global QCD analysis of nuclear parton distribution functions. In addition to the most commonly analyzed data sets for deep inelastic scattering of charged leptons off nuclei and Drell Yan di-lepton production, we include also measurements for neutrino-nuclei scattering as well as inclusive pion production in deuteron-gold collisions. The emerging picture is one of consistency, where universal nuclear modification factors for each parton flavor reproduce the main features of all data without any significant tension among the different sets.Comment: 4 pages, 3 figures, Contribution to DIS2012 proceeding
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