Journal article
Measurement of the tau polarisation at the Z resonance
D Buskulic, D Decamp, C Goy, JP Lees, MN Minard, B Mours, B Pietrzyk, R Alemany, F Ariztizabal, P Comas, JM Crespo, M Delfino, E Fenandez, M Fernandez-Bosman, V Gaitan, L Garrido, T Mattison, A Pacheco, C Padilla, A Pascual Show all
Zeitschrift Fur Physik C Particles and Fields | SPRINGER | Published : 1993
DOI: 10.1007/BF01498618
Abstract
Using 18.8 pb-1 of data collected in 1990 and 1991, ALEPH has measured the tau polarisation in the decay modes τ→ev {Mathematical expression}, τ→μv {Mathematical expression}, τ→πν, τ→ρν and τ→a1ν, using both the individual tau decay kinematics and the event acollinearity. The measurement of the tau polarisation as a function of the production polar angle yields the two parameters Aτ and Ae, where Al=2 gv lgA l/(gv l )2+(gA l)2] The results Aτ=0.143±0.023 and Ae=0.120±0.026 are consistent with the hypothesis of electron-tau universality. Assuming universality yields a measurement of the effective weak mixing angle sin2θw eff=0.2332±0.0022. © 1993 Springer-Verlag.