5,372 research outputs found

    Polarized semi-inclusive electroweak structure functions at next-to-leading-order

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    We present a next-to-leading order (NLO) computation of the full set of polarized and unpolarized electroweak semi-inclusive DIS (SIDIS) structure functions, whose knowledge is crucial for a precise extraction of polarized parton distributions. We focus on the phenomenology of the polarized structure functions for the kinematical conditions that could be reached in an Electron-Ion-Collider. We show that the NLO corrections are sizeable, particularly in the small-xx range. We test the sensitivity of these structure functions on certain quark distributions and compare it to the situation of inclusive DIS and electromagnetic SIDIS.Comment: 17 pages, 5 figure

    Target Fragmentation and Fracture Functions

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    We analyse recent data on the production of forward neutrons in deep inelastic scattering at HERA in the framework of a perturbative QCD description for semi-inclusive processes, which includes fracture functions.Comment: To be published in Proceedings of the Madrid low-x Workshop, Miraflores de la Sierra, June 18-21, 199

    On Kaon production in e+e- and Semi-inclusive DIS reactions

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    We consider semi-inclusive unpolarized DIS for the production of charged kaons and the different possibilities to test the conventionally used assumptions s-\bar=0 and D_d^{K^+-K^-}=0. The considered tests have the advantage that they do not require any knowledge of the fragmentation functions. We also show that measurements of both charged and neutral kaons would allow the determination of the kaon FFs D_q^{K^++K^-} solely from SIDIS measurements, and discuss the comparison of (D_u-D_d)^{K^+-K^-} obtained independently in SIDIS and e+e- reactions. All analysis are performed in LO and NLO in QCD. The feasibility of the tests to HERMES SIDIS data is considered.Comment: 7 pages, NLO analysis for all presented tests and feasibility to HERMES data adde

    Universality of non-leading logarithmic contributions in transverse-momentum distributions

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    We consider the resummation of the logarithmic contributions to the region of small transverse momenta in the distributions of high-mass systems (lepton pairs, vector bosons, Higgs particles, ....) produced in hadron collisions. We point out that the resummation formulae that are usually used to compute the distributions in perturbative QCD involve process-dependent form factors and coefficient functions. We present a new universal form of the resummed distribution, in which the dependence on the process is embodied in a single perturbative factor. The new form simplifies the calculation of non-leading logarithms at higher perturbative orders. It can also be useful to systematically implement process-independent non-perturbative effects in transverse-momentum distributions. We also comment on the dependence of these distributions on the factorization and renormalization scales.Comment: misprints corrected in Eqs. (6), (7) and (12), results unchange

    Direct Higgs production and jet veto at hadron colliders

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    We consider Higgs boson production through gluon--gluon fusion in hadron collisions, when a veto is applied on the transverse momenta of the accompanying hard jets. We compute the QCD corrections to this process at NLO and NNLO, and present numerical results at the Tevatron and the LHC.Comment: 5 pages, 4 ps figures, presented at the XXXVIIth Rencontres de Moriond, QCD and Hadronic interactions, Les Arc1800, Franc

    Higgs production in hadron collisions: soft and virtual QCD corrections at NNLO

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    We consider QCD corrections to Higgs boson production through gluon-gluon fusion in hadron collisions. Using the recently evaluated two-loop amplitude for this process and the corresponding factorization formulae for soft-gluon bremsstrahlung at O(alpha_s^2), we compute the soft and virtual contributions to the NNLO cross section. We also discuss soft-gluon resummation at next-to-next-to-leading logarithmic accuracy. Numerical results for Higgs boson production at the LHC are presented.Comment: 17 pages, 4 figures included. One note and one reference adde

    Higgs production at hadron colliders in (almost) NNLO QCD

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    We compute the soft and virtual NNLO QCD corrections to Higgs production through gluon-gluon fusion at hadron colliders. We present numerical results obtained at the LHC and at the Tevatron Run II.Comment: latex, 5 pages, presented at the XXXVIth Rencontres de Moriond, QCD and Hadronic interactions, Les Arc1800, France and at the 9th International Workshop on Deep Inelastic Scattering DIS2001, Bologna, Ital

    Sea quark and gluon polarization in the nucleon at NLO accuracy

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    We investigate the sea quark polarization in the nucleon by means of a combined next to leading order analysis to the recently enlarged set of inclusive and semi-inclusive polarized deep inelastic scattering data. Using the Lagrange multiplier method, we asses the uncertainty inherent to the extraction of the different spin dependent parton densities in a QCD global fit, and the impact of the increased set of semi-inclusive data now available. We comment on future prospects at RHIC and JLAB and their potential impact in the future determination of polarized parton densities.Comment: 15 pages, 9 figures, 3 table

    Extraction of polarized parton densities from polarized DIS and SIDIS

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    We present results on the quark and gluon polarization in the nucleon obtained in a combined next to leading order analysis to the available inclusive and semi-inclusive polarized deep inelastic scattering data.Comment: Talk given at XIII International Workshop on Deep Inelastic Scattering, April,27 - May,1, 2005, Madison, Wisconsin, USA, 4 pages, 2 figure
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