Abstract Abstract

The mass of the W boson is determined in e+e- collisions at LEP by direct reconstruction of W decays in WW®q[`q]q[`q] and WW®lnq[`q] events. The data sample corresponds to an integrated luminosity of 683 pb-1 collected with the ALEPH detector at centre-of-mass energies from 183 to 209 GeV. The W mass itself is used as an observable to place an upper limit on the effect of colour reconnection in the q[`q]q[`q] channel. The combined result from all channels is

mW = 80... ±0.0.. (stat.) ±0.0.. (syst.)±0.0.. (FSI)±0.017 (LEP) GeV/c2,
where FSI represents the possible effects of final state interactions in the q[`q]q[`q] channel. From two-parameter fits to the q[`q]q[`q], enq[`q], mnq[`q] and tnq[`q] channels, where the W mass and width are decoupled, the average W width is found to be 2... ±0... (stat.) ±0.13 (syst.) GeV/c2, consistent with the Standard Model prediction.

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On 10 Nov 2004, 16:45.