A measurement of the resonance parameters of the neutral intermediate vector boson

This thesis presents a measurement of the 2’ Boson resonance parameters. The measurement was performed at the Stanford Linear Collider using the Mark II detector. Based on a sample of 480 Hadronic and Leptonic decays, the mass is found to be 91.14 f 0.12 GeV/c2, the total width is 2.42 t$$ GeV, and the peak cross section for . all Hadronic events, and for Muon and Tau events with cos &hrust < 0.65 is 45 f4 nb. By constraining the visible width to the Standard Model value for 5 quarks and 3 charged leptons, and allowing the invisible width to be a parameter, the width to invisible decay modes is found to be 0.46fO.lOGeV. Assuming this width comes from massless neutrinos, this measurement corresponds to 2.8 f 0.6 neutrino species. This measurement sets an upper limit of 3.9 neutrino generations at the 95% confidence level, ruling out a fourth generation of Standard Model neutrinos at this level.