Possible deviations in τ polarization in e-e+→τ-τ+ due to exotic-lepton mixing

The τ polarization Pτ(s,cosθ) as a function of the production polar angle θ, the mean τ polarization in the forward hemisphere left-angle Pτ(s)right-angle F, and the total mean τ polarization left-angle Pτ(s)right-angle T in the process e-e+→τ-τ+ are reexamined with the inclusion of mixing between ordinary (l=e,τ) and exotic (El) leptons of type (i) vector singlet (VS), (ii) vector doublet (VD), and (iii) mirror (M) for c.m. energies around the Z peak. For √s ∼MZ, the deviations from standard-model expectations are much less for the M lepton mixing in comparison to those due to the VS or VD lepton mixing. Around the Z peak, the VS (VD) mixing induces negative (positive) deviations. At √s =MZ, for the presently allowed mixing element square, |UτEτ|2=0.02, the expected relative deviations are (i) -11.4% (+13.0%) in Pτ(cosθ=0.75), (ii) -11.8% (+13.5%) in left-angle Pτ(s)right-angle F, and (iii) -23.2% (+27.0%) in left-angle Pτ(s)right-angle T, for VS (VD) types of mixed exotic leptons