Measurement of the W Mass and Width in e+e- Collisions at 183 GeV
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- -> qqqq and 300 W+W- -> qqlnu candidate events are used to obtain a measurement of the mass of the W boson, W_W = 80.39 +- 0.13(stat.) +- 0.05(syst.) GeV assuming the Standard Model relation between M_W and Gam_W. A second fit provides a direct measure of the width of the W boson and gives Gam_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 Gam_W = 1.84 +- 0.32(stat.) +- 0.20(syst.) GeV.