Speaker
Description
Michel parameters (MP) determine the Lorentz structure of the charged weak interaction, they are in the list of the basic properties of every lepton. The difference of the measured MP from their Standard Model expectation will exhibit clear signature of the New Physics. Feasibility study of Michel parameters at the Super Charm-Tau factory and Belle II with polarized electron beam has been carried out. This simple generator level study allows us to estimate the statistical sensitivities to MP as a function of electron beam polarization. Two analysis techniques were tested: the unbinned maximum likelihood fit of the (tau --> lep nu nu; tau --> pi pi0 nu) events in the full nine-dimensional phase space, and unbinned maximum likelihood fit of the (tau --> lep nu nu; tau --> all) in the three-dimensional phase space. Sensitivities to MP were estimated for the whole expected Super Charm-Tau factory and Belle II tau data samples. The impact of the electron beam polarization at the Super Charm-Tau factory is discussed.
