Direct measurement of <italic>W</italic> boson decay width at DO.

Abstract

This thesis presents the first direct measurement of the <italic>W</italic> boson decay width, Gamma_W, with the <italic>W</italic> decay into an electron and neutrino final state using data collected by the DO detector at the Tevatran collider. This analysis has used the <italic>W</italic> event sample collected in the Run I physics program. Backgrounds that contaminate the <italic>W</italic> sample are estimated using additional DO data samples. Detailed Monte Carlo samples are used to template the transverse mass spectrum of the <italic>W</italic> events to extract the <italic>W</italic> decay width. Various sources of the systematic uncertainties of this measurement are investigated. The direct measurement result obtained in this thesis work is Gamma_W = 2.231<super>+0.145</super>_-0.138(stat) +/- 0.092(sys) GeV. This result is consistent with the prediction of the Standard Model and the result from the indirect measurement from the DO experiment.