Measurement of the Michel parameters and the average τ neutrino helicity from τ decays in e+e- → τ+τ-

• Autores: Dova, María Teresa; L3 Collaboration
• Año de publicación: 1996
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ciencias Exactas; Física; Michel parameters; leptons; hadrons
• Institución: Universidad Nacional de La Plata

The Michel parameters ϱ, η, ξ, and ξδ, the chirality parameter ξh and the τ polarization Pτ are measured using 32012 τ pair decays. Their values are extracted from the energy spectra of leptons and hadrons in $\text{τ}{}^{\mathrm{-}}\text{→ l}{}^{\mathrm{-}}\text{ν}{}_{\mathrm{l}}\text{ν}{}_{\mathrm{\tau }}$ and τ− → π−ντ decays, the energy and decay angular distributions in τ− → ϱ−ντ decays, and the correlations in the energy spectra and angular distributions of the decay products. Assuming universality in leptonic and semileptonic τ decays, the results are ϱ = 0.794±0.039±0.031, η = 0.25±0.17±0.11, ξ = 0.94±0.21±0.07, ξδ = 0.81±0.14±0.06, ξh = −0.970±0.053±0.011, and Pτ = −0.154±0.018±0.012. The measurement is in agreement with the V-A hypothesis for the weak charged current.
Facultad de Ciencias Exactas