Measurement of the Tau Lepton Polarisation at LEP2

TL;DR

This paper reports the first measurement of tau lepton polarisation at energies above the Z resonance, using decay spectra at LEP2, confirming Standard Model predictions.

Contribution

It introduces a novel measurement of tau polarisation at LEP2 energies, extending previous studies beyond the Z resonance.

Findings

Measured P_tau = -0.164 +/- 0.125

Result consistent with Standard Model

First such measurement at LEP2 energies

Abstract

A first measurement of the average polarisation P_tau of tau leptons produced in e+e- annihilation at energies significantly above the Z resonance is presented. The polarisation is determined from the kinematic spectra of tau hadronic decays. The measured value P_tau = -0.164 +/- 0.125 is consistent with the Standard Model prediction for the mean LEP energy of 197 GeV.