Electroweak measurements in electron-positron collisions at W-boson-pair energies at LEP
Abstract
Electroweak measurements performed with data taken at the electron–positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb −1 collected by the four LEP experiments ALEPH, DELPHI, L3 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron–positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose–Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, mW and ΓW , the branching fraction of W decays to hadrons, B(W→had) , and the trilinear gauge-boson self-couplings g1Z , κγ and λγ are determined to be: mW=80.376±0.033GeV ΓW=2.195±0.083GeV B(W→had)=67.41±0.27% g1Z=0.984−0.020+0.018 κγ=0.982±0.042 λγ=−0.022±0.019.