Measurement of the e e- → W W - cross section and W decay branching fractions at LEP

Abstract

From a total data sample of 701.1 pb-1 recorded with e +e- centre-of-mass energies of √s = 161-209 GeV with the OPAL detector at LEP, 11693 W-pair candidate events are selected. These data are used to obtain measurements of the W-pair production cross sections at 10 different centre-of-mass energies. The ratio of the measured cross sections to the standard model expectation is found to be: data/SM = 1.002±0.011 (stat.)±0.007 (syst.)±0.005 (theory), where the uncertainties are statistical, experimental systematics and theory systematics respectively. The data are used to determine the W boson branching fractions, which are found to be consistent with lepton universality of the charged current..