A test ofCP-invariance in Z0→τ+τ− using optimal observables

Using 27 490 Z0→τ+τ− decays, accumulated in 1991, 1992 and 1993 with the OPAL detector at LEP, a direct test ofCP-invariance in the neutral current reactione+e−→τ+τ− is performed by measuringCP-odd observables which are proportional to the weak dipole moment of the τ-lepton. A new method based on optimalCP-odd observables constructed from the τ flight and spin directions is employed. More sensitive measurements of the real and, for the first …