9 research outputs found

    Measurement of the W mass in e+e−e^+ e^- collisions at 183 GeV

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    The mass of the W boson is obtained from reconstructed invariant mass distributions in W-pair events. The sample of W pairs is selected from 57 pb−1^{-1} collected with the ALEPH detector in 1997 at a centre-of-mass energy of 183 GeV. The invariant mass distributions of reweighted Monte Carlo events are fitted separately to the experimental distributions in the qqbarqqbarqqbarqqbar and all l\nuqqbar channels to give the following W masses: mWhadronic=80.461±0.177(stat.)±0.045(syst.)±0.056(theory)GeV/c2m_{W}^{hadronic} = 80.461 \pm 0.177(stat.) \pm 0.045(syst.) \pm 0.056(theory) GeV/c^2, mWsemileptonic=80.326±0.184(stat.)±0.040(syst.)GeV/c2m_{W}^{semileptonic} = 80.326 \pm 0.184(stat.) \pm 0.040(syst.) GeV/c^2 where the theory error represents the possible effects of final state interactions. The combination of these two measurements, including the LEP energy calibration uncertainty, gives $m_{W} = 80.393 \pm 0.128(stat.)\pm 0.041(syst.) \pm 0.028(theory)\pm 0.021(LEP) GeV/c^2

    Search for sleptons in e+e−e^+ e^- collisions at centre-of-mass energies up to 184 GeV

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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

    Scalar quark searches in e+e−e^+ e^- collisions at s\sqrt{s} = 181-184 GeV

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    Measurement of W-pair production in e+^{+}e−^{-} collisions at 183 GeV

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    Search for sleptons in e+e−e^+ e^- collisions at centre-of-mass energies up to 184 GeV

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    Resonant structure and flavour tagging in the Bπ±B\pi^{\pm} system using fully reconstructed BB decay

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    Resonant structure and flavour tagging in the Bπ±B\pi^{\pm} system using fully reconstructed BB decay

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