6,187 research outputs found

    Searches for SUSY at LHC

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    One of the main motivations of experiments at the LHC is to search for SUSY particles. The talk is based on recent analyses, performed by CMS Collaboration, within the framework of the Supergravity motivated minimal SUSY extension of the Standard Model. The emphasis is put on leptonic channels. The strategies for obtaining experimental signatures for strongly and weakly interacting sparticles productions, as well as examples of determination of SUSY masses and model parameters are discussed. The domain of parameter space where SUSY can be discovered is investigated. Results show, that if SUSY is of relevance at Electro-Weak scale it could hardly escape detection at LHC.Comment: LaTeX, 6 pages, 8 eps figures. Presented at XXXII Rencontres de Moriond: QCD and High Energy Hadronic Interactions, Les Arcs, Savoie, France, March 22-29, 199

    Υ\Upsilon Polarization at HERA-BB

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    The production of Υ\Upsilon mesons in fixed target pNpN collisions is considered. It is shown that Non-Relativistic QCD predicts Υ\Upsilon states to be produced with sizeable transverse polarization. The possibility of a measurement of the Υ\Upsilon polarization at the HERA-BB experiment is discussed.Comment: 9 pages, LaTeX, with 3 eps figs included with epsfig.st

    Top Mass Determination in Leptonic Final States with J/ψJ/\psi

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    Taking advantage of large top production rates at the LHC, the leptonic final states with J/psi are explored for a precise determination of the top quark mass. The top is partially reconstructed by combining the isolated lepton from the W with the J/psi from the decays of the corresponding b-quark. The method relies, to a large extent, on the proper Monte-Carlo description of top production and decay. The main emphasis is put on the expected systematics uncertainties. Mass measurement accuracy is dominated by the current understanding of theoretical uncertainties which result in a systematic error of <~1 GeV

    Search for the next-to-lightest neutralino

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    We study the inclusive production of the next-to-lightest neutralino chi2, decaying directly, or via slepton, into two leptons and the lightest neutralino. The dilepton invariant mass spectrum in these decays has a characteristic sharp edge near the kinematical upper limit. We propose to exploit this feature as a search strategy for the chi2, and thereby for SUSY. The possibilities to determine neutralinos and slepton masses are also discussed.Comment: LaTeX, 10 pages, 7 eps figures; submitted to Nuclear Physics B; a more detailed version is available under ftp://cmsdoc.cern.ch/documents/97/note97_065.ps.

    Corporate Governance in Companies with State Participation

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    In modern conditions the ongoing development of corporate governance in our country due to several factors. First of all, the Russian economy is increasingly involved in the economic processes of globalization, increased interaction of large Russian companies with the global financial market. In addition, Russia’s largest company significantly expanded its international activities, including through the acquisition of foreign assets. Joint-stock medium-sized companies have realized the need to attract external financing through the search for a strategic investor or access to stock markets. Significant changes made to the corporate legislation

    The Presampler for the Forward and Rear Calorimeter in the ZEUS Detector

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    The ZEUS detector at HERA has been supplemented with a presampler detector in front of the forward and rear calorimeters. It consists of a segmented scintillator array read out with wavelength-shifting fibers. We discuss its desi gn, construction and performance. Test beam data obtained with a prototype presampler and the ZEUS prototype calorimeter demonstrate the main function of this detector, i.e. the correction for the energy lost by an electron interacting in inactive material in front of the calorimeter.Comment: 20 pages including 16 figure

    Color Octet Contribution to J/psi Photoproduction Asymmetries

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    We investigate J/ψJ/\psi photoproduction asymmetries in the framework of the NRQCD factorization approach. It is shown that the color octet contribution leads to large uncertainties in the predicted asymmetries which rules out the possibility to precisely measure the gluon polarization in the nucleon through this final state. For small values of the color octet parameters being compatible with J/ψJ/\psi photoproduction data it appears possible that a measurement of J/ψJ/\psi asymmetries could provide a new test for the NRQCD factorization approach, on one hand, or a measurement of the polarized gluon distribution from low inelasticity events (z<0.7)(z<0.7), on the otherComment: 12 pages, LaTeX, with 6 figs. Final version published in Phys.Rev.

    NLO QCD corrections to off-shell top-antitop production with leptonic decays at hadron colliders

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    We present details of a calculation of the cross section for hadronic top-antitop production in next-to-leading order (NLO) QCD, including the decays of the top and antitop into bottom quarks and leptons. This calculation is based on matrix elements for \nu e e+ \mu- \bar{\nu}_{\mu}b\bar{b} production and includes all non-resonant diagrams, interferences, and off-shell effects of the top quarks. Such contributions are formally suppressed by the top-quark width and turn out to be small in the inclusive cross section. However, they can be strongly enhanced in exclusive observables that play an important role in Higgs and new-physics searches. Also non-resonant and off-shell effects due to the finite W-boson width are investigated in detail, but their impact is much smaller than naively expected. We also introduce a matching approach to improve NLO calculations involving intermediate unstable particles. Using a fixed QCD scale leads to perturbative instabilities in the high-energy tails of distributions, but an appropriate dynamical scale stabilises NLO predictions. Numerical results for the total cross section, several distributions, and asymmetries are presented for Tevatron and the LHC at 7 TeV, 8 TeV, and 14 TeV.Comment: 61 pp. Matches version published in JHEP; one more reference adde
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