Measurement of the Michel Parameter $ρ$ in Muon Decay

dc.creatorTWIST Collaboration
dc.creatorMusser, J. R.
dc.date2004-09-29
dc.date.accessioned2026-07-07T10:28:28Z
dc.date.available2026-07-07T10:28:28Z
dc.descriptionThe TWIST Collaboration has measured the Michel parameter $ρ$ in normal muon decay, $μ^+ \to e^+ ν_e \barν_μ$. In the Standard Model, $ρ$ = 3/4. Deviations from this value require mixing of left- and right-handed muon and electron couplings in the muon-decay Lagrangian. We find $ρ$ = 0.75080 $\pm$ 0.00044(stat.) $\pm$ 0.00093(syst.) $\pm$ 0.00023, where the last uncertainty represents the dependence of $ρ$ on the Michel parameter $η$. This result sets new limits on the $W_L-W_R$ mixing angle in left-right symmetric models.
dc.description4 pages, 3 figures, submitted to PRL
dc.identifierhttps://arxiv.org/abs/hep-ex/0409063
dc.identifierhttp://arxiv.org/abs/hep-ex/0409063
dc.identifierPhys.Rev.Lett.94:101805,2005
dc.identifierdoi:10.1103/PhysRevLett.94.101805
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/177460
dc.subjectHigh Energy Physics - Experiment
dc.titleMeasurement of the Michel Parameter $ρ$ in Muon Decay
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