2,938 research outputs found

    Global Parton Distributions for the LHC Run II

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    We review the next generation global PDF sets: NNPDF3.0, MMHT14 and CT14. We describe the global datasets, particularly the new data from LHC Run 1, recent developments in QCD theory and PDF methodology, improvements in combination and delivery, and future prospects for parton determination at Run 2.Comment: 15 pages, 11 figures; talk given at La Thuile, 3rd March 2015; updated reference

    High Energy Resummation of Drell-Yan Processes

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    We present a computation of the inclusive Drell-Yan production cross-section in perturbative QCD to all orders in the limit of high partonic centre-of-mass energy. We compare our results to the fixed order NLO and NNLO results in MSbar scheme, and provide predictions at NNNLO and beyond. Our expressions may be used to obtain fully resummed results for the inclusive cross-section.Comment: 18 pages, 5 figures: version to be published in NP

    An Improved Splitting Function for Small x Evolution

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    We summarize our recent result for a splitting function for small x evolution which includes resummed small x logarithms deduced from the leading order BFKL equation with the inclusion of running coupling effects. We compare this improved splitting function with alternative approaches.Comment: 5 pages, 2 figures, presented by G.A.at DIS200

    Momentum Conservation at Small x

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    We discuss how momentum conservation is implemented in perturbative computations based on expansions of anomalous dimensions appropriate at small xx. We show that for any given choice of F2F_2 coefficient functions there always exists a factorization scheme where the gluon is defined in such a way that momentum is conserved at next to leading order.Comment: 11 pages, plain TeX with harvma

    Singlet parton evolution at small x: a theoretical update

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    This is an extended and pedagogically oriented version of our recent work, in which we proposed an improvement of the splitting functions at small x which overcomes the apparent problems encountered by the BFKL approach.Comment: 30 pages, 8 figures, latex with sprocl.sty and epsfi

    Perturbative evolution of polarized structure functions

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    We review the perturbative evolution of the polarized structure functions g_1 and their associated parton distribution functions, with particular emphasis on the anomalous coupling of the first moment of the polarized gluon distribution. We also describe the small x behaviour of polarized parton distributions, contrasting it with that of the unpolarized distributions. We then explain how this theoretical analysis affects the extraction of the singlet axial charge from experimental data on g_1, and show that it may be possible to use such data to infer the existence of polarized gluons in the nucleon.We review the perturbative evolution of the polarized structure functions g_1 and their associated parton distribution functions, with particular emphasis on the anomalous coupling of the first moment of the polarized gluon distribution. We also describe the small x behaviour of polarized parton distributions, contrasting it with that of the unpolarized distributions. We then explain how this theoretical analysis affects the extraction of the singlet axial charge from experimental data on g_1, and show that it may be possible to use such data to infer the existence of polarized gluons in the nucleon
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