WG4 The Final Measurement of the Muon Decay Parameters from the TWIST Experiment

Not scheduled


Dr Ryan Bayes (University of Glasgow)


The TWIST (TRIUMF Weak Interaction Symmetry Test) has completed a measurement of the muon decay energy-angle spectrum with the best precision in the world [1]. This experiment consists of a simultaneous measurement of the parameters ρ, δ, and Pμξ, from highly polarized muons, to test the validity of the Standard Model (SM) in a purely leptonic interaction. The measurement of these parameters sets new limits on the fundamental coupling constants of the muon and extensions to the SM---such as left right symmetric models. The determination of the systematic uncertainties will be discussed as their control was a central concern for the experiment. The final TWIST results will be given and placed in context for physics beyond the SM. [1] R. Bayes et al, Phys. Rev. Lett 106, 41802 (2011).

Primary author

Dr Ryan Bayes (University of Glasgow)


Gersende Prior (Universite de Geneve (CH))

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