The mass of the W boson is determined in e+e- collisions at LEP by the direct reconstruction of W decays in WW → qq̄qq̄ and WW → ℓvqq̄ 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/c2, where FSI represents the possible effects of final state interactions in the qq̄qq̄ channel. In a second two-parameter fit to the qq̄qq̄, evqq̄ and μvqq̄ 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/c2, 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 172GeV and direct reconstruction at 172 and 183 GeV gives mW = 80.418 ± 0.061(stat.) ± 0.040(syst.) ± 0.019(FSI) ± 0.017(LEP) GeV/c2.
|Journal||European Physical Journal C|
|Publication status||Published - 1 Jan 2000|