Observations and measurement of W boson production and triple gauge couplings at LEP II

Abstract

W-Pair and Single-W production events are observed at LEP, the Large Electron Positron collider at CERN, using the L3 detector. All decay channels are considered, and data taken in the years 1998 and 1999, with electron-positron collision centre-of-mass energies from 189 GeV to 202 GeV are analysed. The integrated luminosity of the analysed data corresponds to approximately 400pb-1, and a total of approximately 5000 W-pair events and 100 single-W events are selected. The observed cross sections of these W production processes and the differential distributions of the event shapes are then used to measure the couplings of Wbosons with Z bosons and photons. Emphasis is placed on the unambiguous and efficient combination of the information from the different production and decay channels. For the couplings in the model in which gauge invariance is realised linearly, the following results are obtained ... where the errors shown are statistical, systematic and theoretical respectively. All results show consistency with expectations from the Standard Model.