A Measurement of tau polarization at LEP.

L3 COLL., P. ACHARD; MT DOVA ET AL

PHYSICS LETTERS B

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 1994 vol. 341 p. 245 - 260

0370-2693

With a data sample of 86 000 Z --> τ+τ-(γ) events collected in 1990 through 1993 we have measured the polarization of τ-leptons as a function of the production polar angle using the following 1-prong τ decay modes: τ--->e-vevτ, τ--->π- (K-)vτ, τ--->ϱ-vτ and τ--->a1-vτ. We obtain for the ratio vector to axial-vector weak neutral couplings for electrons gVe/gAe=0.0791+/-0.0099(stat)+/-0.0025 (syst) and taus gVτ/gAτ=0.0752+/-0.0063 (stat)+/-0.0045 (syst) consistent with the hypothesis of e - τ universality. Assuming universality of the e - τ neutral current we determine the effective electroweak mixing angle to be sin2 θeffw = 0.2309 +/- 0.0016.