11 research outputs found

    Study of muon-pair production at centre-of-mass energies from 20 to 136 GeV with the Aleph detector

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    The total cross section and the forward-backward asymmetry for the process e+eμ+μ(nγ)e^+ e^- \rightarrow \mu^+ \mu^- (n \gamma) are measured in the energy range 20-136 GeV by reconstructing the effective centre-of-mass energy after initial state radiation. The analysis is based on the data recorded with the ALEPH detector at LEP between 1990 and 1995, corresponding to a total integrated luminosity of 143.5 pb1\mathrm{pb}^{-1}. Two different approaches are used: in the first one an exclusive selection of events with hard initial state radiation in the energy range 20-88 GeV is directly compared with the Standard Model predictions showing good agreement. In the second one, all events are used to obtain a precise measurement of the energy dependence of σ0\sigma^0 and AFB0A_{\mathrm{FB}}^0 from a model independent fit, enabling constraints to be placed on models with extra Z bosons

    Differentiation and Viral Involvement in Differentiation of Transformed Mouse and Rat Erythroid Cells

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    Measurement of the axial-vector tau spectral functions and determination of αs\alpha_{s}(Mτ2^2_\tau) from hadronic tau decays

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    Search for evidence of compositeness at LEP I

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    Measurement of the axial-vector tau spectral functions and determination of αs\alpha_{s}(Mτ2^2_\tau) from hadronic tau decays

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    A measurement of the semileptonic branching ratio BR(bbˉplνb-\bar b \to pl\nuX) and a study of inclusive π±/,K±,(p,p)\pi^{\pm}/,K^{\pm},(p,p) production in Z decay

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    Search for evidence of compositeness at LEP I

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    Determination of Vub\mid V_{ub} \mid from the Measurement of the Inclusive Charmless Semileptonic Branching Ratio of b hadrons

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    From a study of the kinematic properties of the final state produced in the semileptonic decays b-->X l nu, the inclusive charmless semileptonic branching ratio of b hadrons is measured. With a sam ple of 3.6 million hadronic Z decays recorded between 1992 and 1995 with the ALEPH detector at LEP, the value Br(b-->X_u l nu) is determined to be (1.73 +- 0.55_stat +- 0.55_syst)*10^{-3}, where X_u represents any charmless hadronic state and b is a mixture of b hadrons weighted by their production rates. This measurement yields the result |V_ub|^2= (18.68 +- 5.94_stat +- 5.94_syst +- 1 .45_HQE)*10^{-6}, where the last error comes from the conversion of the branching ratio to the CKM matrix element squared
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