19 research outputs found

    Summary of the SUSY Working Group of the 1999 Les Houches Workshop

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    The results obtained by the Working Group on Supersymmetry at the 1999 Les Houches Workshop on Collider Physics are summarized. Separate chapters treat "general" supersymmetry, R-parity violation, gauge mediated supersymmetry breaking, and anomaly mediated supersymmetry breaking.Comment: LaTeX, 110 pages with numerous .ps and .eps files. proc.tex is main tex fil

    QCD correction to gluino decay to ttˉχ~10t\bar{t}\tilde{\chi}^0_1 in the MSSM

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    We calculate the complete next-to-leading order QCD corrections to the three-body decay of gluino into top-pair associated with a lightest neutralino in the minimal supersymmetric standard model. We obtain that the LO and NLO QCD corrected decay widths of g~ttˉχ~10\tilde{g} \to t \bar{t} \tilde{\chi}_1^0 at the SPS6{\rm SPS 6} benchmark point are 0.1490GeV0.1490 GeV and 0.1069 GeV respectively, and the relative correction is -28.2%. We investigate the dependence of the QCD correction to g~ttˉχ~10\tilde{g} \to t \bar{t} \tilde{\chi}_1^0 on tanβ\tan\beta and the masses of gluino, scalar top quarks and the lightest neutralino around the SPS6{\rm SPS6} benchmark point, separately. We find that the NLO QCD corrections suppress the LO decay width, and the absolute relative correction can exceed 30% in some parameter space. Therefore, the QCD corrections to the three-body decay g~ttˉχ~10\tilde{g} \to t\bar{t}\tilde{\chi}^0_1 should be taken into account for the precise experimental measurement at future colliders. Moreover, we study the distributions of the top-pair invariant mass (MttˉM_{t\bar t}) and the missing energy (EmissE^{miss}), and find that the line shapes of the LO distributions of MttˉM_{t\bar t} and EmissE^{miss} are not obviously distorted by the NLO QCD corrections.Comment: 23 pages, 10 figure

    TESLA Technical Design Report Part III: Physics at an e+e- Linear Collider

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    The TESLA Technical Design Report Part III: Physics at an e+e- Linear ColliderComment: 192 pages, 131 figures. Some figures have reduced quality. Full quality figures can be obtained from http://tesla.desy.de/tdr. Editors - R.-D. Heuer, D.J. Miller, F. Richard, P.M. Zerwa

    Measurements of the leptonic branching fractions of the τ\tau

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    Data collected with the DELPHI detector from 1993 to 1995 combined with previous DELPHI results for data from 1991 and 1992 yield the branching fractions B({\tau \rightarrow \mbox{\rm e} \nu \bar{\nu}}) = (17.877 \pm 0.109_{stat} \pm 0.110_{sys} )\% and B(τμννˉ)=(17.325±0.095stat±0.077sys)%B({\tau \rightarrow \mu \nu \bar{\nu}}) = (17.325 \pm 0.095_{stat} \pm 0.077_{sys} )\%

    Search for scalar fermions and long-lived scalar leptons at centre-of-mass energies of 130 GeV to 172 GeV

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    Data taken by DELPHI during the 1995 and 1996 LEP runs have been used to search for the supersymmetric partners of electron, muon and tau leptons and of top and bottom quarks. The observations are in agreement with standard model predictions. Limits are set on sfermion masses. Searches for long lived scalar leptons from low scale supersymmetry breaking models exclude stau masses below 55~GeV/c2^2 at the 95\% confidence level, irrespective of the gravitino mass

    Investigation of the splitting of quark and gluon jets

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    The splitting processes in identified quark and gluon jets are investigated using longitudinal and transverse observables. The jets are selected from symmetric three-jet events measured in Z decays with the Delphi detector in 1991-1994. Gluon jets are identified using heavy quark anti-tagging. Scaling violations in identified gluon jets are observed for the first time. The scale energy dependence of the gluon fragmentation function is found to be about two times larger than for the corresponding quark jets, consistent with the QCD expectation TeX . The primary splitting of gluons and quarks into subjets agrees with fragmentation models and, for specific regions of the jet resolution TeX , with NLLA calculations. The maximum of the ratio of the primary subjet splittings in quark and gluon jets is TeX . Due to non-perturbative effects, the data are below the expectation at small TeX . The transition from the perturbative to the non-perturbative domain appears at smaller TeX for quark jets than for gluon jets. Combined with the observed behaviour of the higher rank splittings, this explains the relatively small multiplicity ratio between gluon and quark jets

    Measurement of the gluon fragmentation function and a comparison of the scaling violation in gluon and quark jets

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    The Higgs Working Group: Summary Report

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    Latex, 100 pages, style files included, also available at http://www.lpm.univ-montp2.fr:7082/~djouadi/houches/houches99.htmlReport of the Higgs working group for the Workshop "Physics at TeV Colliders", Les Houches, France 8-18 June 1999. It contains 6 separate sections: 1. Measuring Higgs boson couplings at the LHC. 2. Higgs boson production at hadron colliders at NLO. 3. Signatures of Heavy Charged Higgs Bosons at the LHC. 4. Light stop effects and Higgs boson searches at the LHC. 5. Double Higgs production at TeV Colliders in the MSSM. 6. Programs and Tools for Higgs Bosons

    The Snowmass Points and Slopes: benchmarks for SUSY searches

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    The ``Snowmass Points and Slopes'' (SPS) are a set of benchmark points and parameter lines in the MSSM parameter space corresponding to different scenarios in the search for Supersymmetry at present and future experiments. This set of benchmarks was agreed upon at the 2001 ``Snowmass Workshop on the Future of Particle Physics'' as a consensus based on different existing proposals.Comment: 12 pages, 3 figure
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