# Measurement of the Tau polarisation at LEP

Abstract : The polarisation of $\tau$'s produced in Z decay is measured using 160 pb$^{-1}$ of data accumulated at LEP by the ALEPH detector between 1990 and 1995. The variation of the polarisation with polar angle yields the two parameters ${\cal A}_e = 0.1504 \pm 0.0068$ and ${\cal A}_{\tau} = 0.1451 \pm 0.0059$ which are consistent with the hypothesis of $e$-$\tau$ universality. Assuming universality, the value ${\cal A}_{e{-}\tau} = 0.1474 \pm 0.0045$ is obtained from which the effective weak mixing angle $\sin^2 {\theta_{\mathrm{W}}^{\mathrm{eff}}} =0.23147 \pm 0.00057$ is derived.
Document type :
Journal articles

Cited literature [11 references]

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Submitted on : Thursday, August 30, 2001 - 10:31:56 AM
Last modification on : Friday, October 22, 2021 - 4:28:57 AM
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### Identifiers

• HAL Id : in2p3-00009918, version 1

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### Citation

A. Heister, S. Schael, R. Barate, I. de Bonis, D. Decamp, et al.. Measurement of the Tau polarisation at LEP. European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2001, 20, pp.401-430. ⟨in2p3-00009918⟩

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