Measurement of the W Mass and Width in $e^+ e^-$ Collisions at 189 GeV

Abstract : The mass of the W boson is determined in e+e- collisions at LEP by the direct reconstruction of W decays in WW->qqqq and WW->lvqq events, supplemented by measurements using the kinematic properties of the leptons in the WW->lvlv decay channel. The main sample of W pairs is selected from an integrated luminosity of 174 pb^-1 collected with the ALEPH detector in 1998 at a centre-of-mass energy of 188.63 GeV.The combined result from all channels is mW = 80.432+-0.072(stat.)+-0.041(syst.)+-0.019(FSI)+-0.017(LEP) GeV/c^2, where FSI represents the possible effects of final state interactions in the qqqq channel. In a second two-parameter fit to the qqqq, evqq and mvqq channels, where the W mass and width are decoupled, the average W width is found to be 2.24+-0.20(stat.)+-0.13(syst.) GeV/c^2, consistent with the Standard Model prediction. The combination of the mass measurement presented in this paper together with those derived previously from the W pair cross section at 161 and 172 GeV and direct reconstruction at 172 and 183 GeV gives mW = 80.418+-0.061(stat.)+-0.038(syst.)+-0.019(FSI)+-0.017(LEP) GeV
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Submitted on : Thursday, November 16, 2000 - 3:22:00 PM
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• HAL Id : in2p3-00005329, version 1

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R. Barate, D. Decamp, P. Ghez, C. Goy, S. Jezequel, et al.. Measurement of the W Mass and Width in $e^+ e^-$ Collisions at 189 GeV. European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2000, 17, pp.241-261. ⟨in2p3-00005329⟩

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