Measurement of the W mass and width in e(+)e(-) collisions at 183 GeV

Abstract Using a data sample of 57 pb −1 recorded at a centre-of-mass energy of 183 GeV with the OPAL detector at LEP, 282 W + W − → q q q q and 300 W + W − → q q l ν l candidate events are used to obtain a measurement of the mass of the W boson, M W =80.39±0.13(stat.)±0.05(syst.) GeV, assuming the Standard Model relation between M W and Γ W . A second fit provides a direct measure of the width of the W boson and gives Γ W =1.96±0.34(stat.)±0.20(syst.) GeV. These results are combined with previous OPAL results to obtain M W =80.38±0.12(stat.)±0.05(syst.) GeV and Γ W =1.84±0.32(stat.)±0.20(syst.) GeV.