1,317,830 research outputs found

    Threshold resummation for gaugino pair production at hadron colliders

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    We present a complete analysis of threshold resummation effects on direct light and heavy gaugino pair production at the Tevatron and the LHC. Based on a new perturbative calculation at next-to-leading order of SUSY-QCD, which includes also squark mixing effects, we resum soft gluon radiation in the threshold region at leading and next-to-leading logarithmic accuracy, retaining at the same time the full SUSY-QCD corrections in the finite coefficient function. This allows us to correctly match the resummed to the perturbative cross section. Universal subleading logarithms are resummed in full matrix form. We find that threshold resummation slightly increases and considerably stabilizes the invariant mass spectra and total cross sections with respect to the next-to-leading order calculation. For future reference, we present total cross sections and their theoretical errors in tabular form for several commonly used SUSY benchmark points, gaugino pairs, and hadron collider energies.Comment: 28 pages, 5 tables, 17 figure

    Joint Resummation for Gaugino Pair Production at Hadron Colliders

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    We calculate direct gaugino pair production at hadron colliders at next-to-leading order of perturbative QCD, resumming simultaneously large logarithms in the small transverse-momentum and threshold regions to next-to-leading logarithmic accuracy. Numerical predictions are presented for transverse momentum and invariant mass spectra as well as for total cross sections and compared to results obtained at fixed order and with pure transverse-momentum and threshold resummation. We find that our new results are in general in good agreement with the previous ones, but often even more precise.Comment: 21 pages, 5 figures, 1 tabl

    Obstacles to shared decision-making in psychiatric practice: Findings from three observational studies

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    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This thesis aims to make contributions at substantive, methodological and theoretical levels. First, the findings from three observational studies are combined to identify obstacles to the use of shared decision-making in modern psychiatric practice. Particular attention is paid to how patients' choices about their treatment are facilitated or constrained by the actions of mental health professionals. A typology of pressure is constructed, based on detailed analyses of how pressure is applied and resisted in routine encounters (outpatient consultations) and "crisis' situations (assessments for compulsory admission to hospital, and ward rounds in acute inpatient care). Findings from two ethnographies and one conversation analysis (CA) study are presented. 'Meaning' is central to the write-up of each set of findings, however while the analytic focus of the ethnographies is 'insider' knowledge and meanings, in the CA study it is gn the activities that make those meanings possible in the first place. The methodological contribution of the thesis stems from its demonstration of how to produce a coherent, unified research account from two very different versions of qualitative inquiry. Despite the potential for analytic inconsistency, the thesis arguably has far greater force and persuasiveness as a result of the attempt to combine, compare and contrast findings from three studies. It is contended that a sound theoretical base for sociological research may be created by combining Goffman's micro-sociology with Foucault's analyses of disciplinary power/knowledge in one of a number of ways. A Goffmanian 'home base' is adopted for this thesis, with Foucauldian thinking applied to add a historical, 'macro' dimension to the analysis that Goffman's work so conspicuously lacks. Foucault's work also provides the conceptual tools for examining the more subtle form of control through expertise that would be missed in a purely Goffmanian study.Department of Health, Eli Lilly, and Dr Jim Birle

    Kinetic Approach to Fractional Exclusion Statistics

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    We show that the kinetic approach to statistical mechanics permits an elegant and efficient treatment of fractional exclusion statistics. By using the exclusion-inclusion principle recently proposed [Phys. Rev. E49, 5103 (1994)] as a generalization of the Pauli exclusion principle, which is based on a proper definition of the transition probability between two states, we derive a variety of different statistical distributions interpolating between bosons and fermions. The Haldane exclusion principle and the Haldane-Wu fractional exclusion statistics are obtained in a natural way as particular cases. The thermodynamic properties of the statistical systems obeying the generalized exclusion-inclusion principle are discussed.Comment: 6 pages, REVTE

    Probing the unparticle signal in b→db \to d penguin processes

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    We investigate the effect of unparticles in the pure b→d b \to d penguin processes B0→K0Kˉ0 B^0 \to K^0 \bar K^0 and B+,0→ϕπ+,0B^{+,0} \to \phi \pi^{+,0} . Since these processes receive dominant contributions due to the {\it top} quark in the loop, direct and mixing-induced CP asymmetry parameters in these processes are expected to be vanishingly small in the standard model. We find that due to the unparticle effect sizable nonzero CP violation could be possible in these channels.Comment: 12 pages, 4 figures, version to appear in Phys. Lett.

    Emeritus Faculty: Alan Hornstein Retires

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