Measurement of τ polarization in e+e- annihilation at √s = 58 GeV

The polarization of τ leptons in the reaction e⁺e^- -> τ⁺τ^- has been measured using a e⁺e^- collider, TRISTAN, at the center-of-mass energy of 58 GeV. From the kinematical distributions of daughter particles in ν -> eνν, μνν, ρν or π(K)ν decays, the average polarization of τ^- and its forward-backward asymmetry have been evaluated to be 0.012+/-0.058 and 0.029+/-0.057, respectively.