296 research outputs found

    Soft gluon resummation for squark and gluino pair-production at hadron colliders

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    We report on the study of soft gluon effects in the production of squarks and gluinos at hadron colliders. Close to production threshold, the emission of soft gluon results in the appearence of large logarithmic corrections in the theoretical expressions. In order to resum these corrections at next-to-leading-logarithmic accuracy appropriate one-loop anomalous dimensions have to be calculated. We present the calculation of the anomalous dimensions for all production channels of squarks and gluinos and provide numerical predictions for the Tevatron and the LHC.Comment: 6 pages, talk given at RADCOR 2009 - 9th International Symposium on Radiative Corrections (Applications of Quantum Field Theory to Phenomenology) October 25-30 2009, Ascona, Switzerlan

    Treatment of Heavy Quarks in Deeply Inelastic Scattering

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    We investigate a simplified version of the ACOT prescription for calculating deeply inelastic scattering from Q^2 values near the squared mass M_H^2 of a heavy quark to Q^2 much larger than M_H^2.Comment: 14 pages, 5 figure

    Parton distribution functions from the precise NNLO QCD fit

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    We report the parton distribution functions (PDFs) determined from the NNLO QCD analysis of the world inclusive DIS data with account of the precise NNLO QCD corrections to the evolution equations kernel. The value of strong coupling constant \alpha_s^{NNLO}(M_Z)=0.1141(14), in fair agreement with one obtained using the earlier approximate NNLO kernel by van Neerven-Vogt. The intermediate bosons rates calculated in the NNLO using obtained PDFs are in agreement to the latest Run II results.Comment: 8 pages, LATEX, 2 figures (EPS

    Prospects of Open Charm Production at GSI-FAIR and J-PARC

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    We present a detailed phenomenological study of the prospects of open charm physics at the future pˉp\bar{p}p and pppp facilities GSI-FAIR and J-PARC, respectively. In particular, we concentrate on differential cross sections and the charge and longitudinal double-spin asymmetries at next-to-leading order accuracy. Theoretical uncertainties for the proposed observables are estimated by varying the charm quark mass and the renormalization and factorization scales.Comment: 11 pages, 13 figure

    Heavy Flavours at Colliders

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    I review some topics in the production and decays of heavy flavours that are relevant for collider physics. In particular, I discuss the present status and some recent progress related to masses, parton densities and fragmentation functions of heavy quarks, as well as threshold resummation, polarized onium production at high transverse momentum, and a factorization theorem for B→ππB \to\pi\pi decays.Comment: 12 pages. Plenary talk given at UK Phenomenology Workshop on Collider Physics, Durham, England, 19-24 Sep 1999 Comments and references adde

    Mellin Representation for the Heavy Flavor Contributions to Deep Inelastic Structure Functions

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    We derive semi--analytic expressions for the analytic continuation of the Mellin transforms of the heavy flavor QCD coefficient functions for neutral current deep inelastic scattering in leading and next-to-leading order to complex values of the Mellin variable NN. These representations are used in Mellin--space QCD evolution programs to provide fast evaluations of the heavy flavor contributions to the structure functions F2(x,Q2),FL(x,Q2)F_2(x,Q^2), F_L(x,Q^2) and g1(x,Q2)g_1(x,Q^2).Comment: 13 pages Letex, 1 style file, 10 eps figure

    Single Top Quark Production as a Probe for Anomalous Moments at Hadron Colliders

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    Single production of top quarks at hadron colliders via gWgW fusion is examined as a probe of possible anomalous chromomagnetic and/or chromoelectric moment type couplings between the top and gluons. We find that this channel is far less sensitive to the existence of anomalous couplings of this kind than is the usual production of top pairs by gggg or qqˉq\bar q fusion. This result is found to hold at both the Tevatron as well as the LHC although somewhat greater sensitivity for anomalous couplings in this channel is found at the higher energy machine.Comment: New discussion and 10 new figures added. uuencoded postscript fil
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