A Study of the decays of tau leptons produced on the Z resonance at LEP
(1992) Zeitschrift für Physik. C, Particles and fields — Vol. 55, n° 4, p. 555-567 (1992)
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- Abstract
- From the analysis of a data sample corresponding to an integrated luminosity of 4.63 pb−1 taken during the 1990 run of LEP at centre of mass energies between 88.2 GeV an 94.2 GeV, the tau decays τ−→e−vˉevτ,τ−→μ−vˉμvτ,τ−→π−(K−)vτ,τ−→ρ−vτ and their charge conjugates have been studied. The following branching ratios have been measured; BR(τ−→e−vˉevτ)=18.6±0.8(stat.)±0.6(sys.)%, , BR(τ−→μ−vˉμvτ)=17.4±0.7±0.6%, , Br(τ− → π− (K−)vτ)=11.9±0.7±0.7%, BR (τ− → ρ− vτ)= 22.4±0.8±1.3%, in good agreement with world averages. The measured electronic and muonic branching ratios lead to a measurement of the strong coupling constant, αs (mτ) = 0.26 −0.12 +0.09 . Extrapolating the αs value fromm τ tom Z yields αs (mZ) = 0.109 −0.028 +0.012 . The average polarizationP τ of taus produced in Z → τs τs decays has also been measured using the above decay modes. The weighted mean of the polarizations obtained from the four decay modes isP τ=−0.24±0.07. This value ofP τ gives, in the improved Born approximation, a ratio between the axial and vector coupling constants of the tau of υτ/aτ = 0.12 ± 0.04, and hence a value of the effective electroweak mixing parameter sin2 θW(m Z 2 ).
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Abreu, P., Cortina Gil, E., DELPHI Collaboration, & et al. (1992). A Study of the decays of tau leptons produced on the Z resonance at LEP. Zeitschrift für Physik. C, Particles and fields, 55(4), 555-567. https://doi.org/10.1007/BF01561293 (Original work published 1992)