A Precision Measurement of the Z0 Lineshape Parameters for the Process Z0 2![tau]+[tau]-
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Published: 1996
Total Pages: 283
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DOWNLOAD EBOOKIn this dissertation, a measurement of the partial decay width of the process Z0 → [tau]+[tau]- using data collected during 1993 and 1994 at the OPAL detector at CERN is described. The cross sections of this process at three center-of-mass energies near the Z0 resonance were determined, and from a fit to those cross sections, the mass of the Z0, its total decay width and its partial decay width into [tau]+[tau]- final states were determined as MZ = 91.183 ± 0.020 GeV, [Gamma]tot = 2.514 ± 0.018 GeV and [Gamma][tau][tau] = 84.54 ± 0.59 MeV. Using published results for MZ, and [Gamma]tot with higher accuracy, a value for the partial decay width of [Gamma][tau][tau] = 84.02 ± 0.20 MeV was obtained. Further using published results for the decay width of the Z0 into quark pair final states, the invisible decay width of the Z0 was determined as [Gamma]inv = 496.9 ± 4.1 MeV, and the number of neutrino generations was determined as Nv = 2.974 ± 0.025(exp) ± 0.007 (mtop, MHiggs). All results were found to be in good agreement with the Standard Model predictions and were consistent with the assumption of lepton universality within the Standard Model framework.
