1,741 research outputs found

    Determination of the QCD color factor ratio CA/CF from the scale dependence of multiplicity in three jet events

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    I examine the determination of the QCD color factor ratio CA/CF from the scale evolution of particle multiplicity in e+e- three jet events. I fit an analytic expression for the multiplicity in three jet events to event samples generated with QCD multihadronic event generators. I demonstrate that a one parameter fit of CA/CF yields the expected result CA/CF=2.25 in the limit of asymptotically large energies if energy conservation is included in the calculation. In contrast, a two parameter fit of CA/CF and a constant offset to the gluon jet multiplicity, proposed in a recent study, does not yield CA/CF=2.25 in this limit. I apply the one parameter fit method to recently published data of the DELPHI experiment at LEP and determine the effective value of CA/CF from this technique, at the finite energy of the Z0 boson, to be 1.74+-0.03+-0.10, where the first uncertainty is statistical and the second is systematic.Comment: 20 pages including 6 figures Version 2 corrects typographical error in equation (2

    Basketball game-related statistics that discriminate between teams season-long success

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    The aim of the present study was to identify the game-related statistics that discriminate between season-long successful and unsuccessful basketball teams participating in the Spanish Basketball League (LEB1). The sample included all 145 average records per season from the 870 games played between the 2000-2001 and the 2005-2006 regular seasons. The following game-related statistics were gathered from the official box scores of the Spanish Basketball Federation: 2- and 3-point field-goal attempts (both successful and unsuccessful), free-throws (both successful and unsuccessful), defensive and offensive rebounds, assists, steals, turnovers, blocks (both made and received), and fouls (both committed and received). To control for season variability, all results were normalized to minutes played each season and then converted to z-scores. The results allowed discrimination between best and worst teams' performances through the following game-related statistics: assists (SC=0.47), steals (SC=0.34), and blocks (SC=0.30). The function obtained correctly classified 82.4% of the cases. In conclusion, season-long performance may be supported by players' and teams' passing skills and defensive preparation

    Next-to-Leading Order Calculation of Four-Jet Shape Variables

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    We present the next-to-leading order calculation of two four-jet event shape variables, the D parameter and acoplanarity differential distributions. We find large, more than 100% radiative corrections. The theoretical prediction for the D parameter is compared to L3 data obtained at the Z peak and corrected to hadron level.Comment: 11 pages, latex with aps, epsf, rotate styles 3 tables, 3 figures typo in eq. 10 corrected, note and reference added, introduction revise

    Inclusive B-Meson Production in e^+ e^- and p p-bar Collisions

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    We provide nonperturbative fragmentation functions for B mesons, both at leading and next-to-leading order in the MS-bar factorization scheme with five massless quark flavors. They are determined by fitting the fractional energy distribution of B mesons inclusively produced in e^+ e^- annihilation at CERN LEP1. Theoretical predictions for the inclusive production of B mesons with high transverse momenta in p p-bar scattering obtained with these fragmentation functions nicely agree, both in shape and normalization, with data recently taken at the Fermilab Tevatron.Comment: 20 pages (Latex), 6 figures (Postscript

    Four-jet angular distributions and color charge measurements: leading order versus next-to-leading order

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    We present the next-to-leading order perturbative QCD prediction to the four-jet angular distributions used by experimental collaborations at LEP for measuring the QCD color charge factors. We compare our results to ALEPH data corrected to parton level. We perform a leading order ``measurement'' of the QCD color factor ratios by fitting the leading order perturbative predictions to the next-to-leading order result. Our result shows that in an experimental analysis for measuring the color charge factors the use of the O(αs3\alpha_s^3) QCD predictions instead of the O(αs2\alpha_s^2) results may shift the center of the fit by a relative factor of 1+2\as in the TR/CFT_R/C_F direction.Comment: 14 pages, 10 tables, 5 figures, revtex, eps style

    A relativistic chiral quark model for pseudoscalar emission from heavy mesons

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    The amplitudes for one-pion mediated transitions between heavy meson excited states are obtained in the framework of the relativistic chiral quark model. The effective coupling constants to pions and the decay widths of excited heavy mesons with l<=2 for non-radially excited, and the l=0 radially excited mesons are presented for both charmed and beauty mesons. We also discuss the allowed decays of strange excited heavy mesons by emission of a K-meson.Comment: 20 pages, revte

    Model independent results for BD1(2420)νˉB\to D_1(2420)\ell\bar\nu and BD2(2460)νˉB\to D_2^*(2460)\ell\bar\nu at order ΛQCD/mc,b\Lambda_{QCD}/m_{c,b}

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    Exclusive semileptonic B decays into D1D_1 and D2D_2^* mesons are investigated including order ΛQCD/mc,b\Lambda_{QCD}/m_{c,b} corrections using the heavy quark effective theory. At zero recoil, the ΛQCD/mc,b\Lambda_{QCD}/m_{c,b} corrections can be written in terms of the leading Isgur-Wise function for these transitions, τ\tau, and known meson mass splittings. We obtain an almost model independent prediction for the shape of the spectrum near zero recoil, including order ΛQCD/mc,b\Lambda_{QCD}/m_{c,b} corrections. We determine τ(1)\tau(1) from the measured BD1νˉB\to D_1\ell\bar\nu branching ratio. Implications for B decay sum rules are discussed.Comment: 11 pages, revte
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