Measurement of the Michel parameters and the average τ neutrino helicity from τ decays in e+e- → τ+τ-
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 <math><mtext>τ</mtext><msup><mi></mi><mn>−</mn...
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| Autores principales: | , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
| Publicado: |
1996
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| Materias: | |
| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/80885 |
| Aporte de: |
| Sumario: | 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 <math><mtext>τ</mtext><msup><mi></mi><mn>−</mn></msup><mtext> → l</mtext><msup><mi></mi><mn>−</mn></msup><mtext>ν</mtext><msub><mi></mi><mn>l</mn></msub><mtext>ν</mtext><msub><mi></mi><mn>τ</mn></msub></math> 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. |
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