Measurements of the tau polarization in Z0 decays
(1995) Zeitschrift für Physik. C, Particles and fields — Vol. 67, n° 2, p. 183-201 (1995)
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- Abstract
- A sample of Z0→τ+τ− events observed in the DELPHI detector at LEP in 1991 and 1992 is analysed to measure the τ polarisation in the exclusive decay channels evvˉ , μvvˉ , πν, ρν and a1ν. The τ polarisation is also measured with an inclusive hadronic analysis which benefits from a higher efficiency and a better systematic precision than the use of the exclusive decay modes. The results have been combined with those published on the 1990 data. A measurement of the τ polarisation as a function of production angle yields the values for the mean τ polarisation 〈P〉τ=−0.148±0.022 and for the Z0 polarisationP Z=−0.136±0.027. These results are used to determine the ratio of vector to axial-vector effective couplings for taus vˉτ/aˉτ=0.074±0.011 , and for electrons vˉe/aˉe=0.068±0.014 , compatible with e-τ universality. With the assumption of lepton universality, the ratio of vector to axial-vector effective couplings for leptons vˉl/aˉl=0.072±0.008 is obtained, implying a value of the effective weak mixing angle sin2θ eff lept =0.2320±0.0021.183-201
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Citations
Abreu, P., Cortina Gil, E., DELPHI Collaboration, & et al. (1995). Measurements of the tau polarization in Z0 decays. Zeitschrift für Physik. C, Particles and fields, 67(2), 183-201. https://doi.org/10.1007/BF01571280 (Original work published 1995)