τ weak dipole moments from azimuthal asymmetries

Abstract We show that transverse and normal single-tau polarization of tau pairs produced at e+ e− unpolarized collisions, at the Z peak, are sensitive to weak (magnetic and electric) dipole moments of the tau. We also show how these components of the τ polarization are accessible by measuring appropriate azimuthal asymmetries in the angular distribution of its decay products. Sensitivities of the order of 10−18 e · cm, for the weak-electric dipole moment, and 10−4 (10−3), for the real (imaginary) part of the weak-magnetic dipole moment of τ, may be achieved. Compatible bounds are also presented from spin-spin correlated asymmetries.