Measurement of the weak dipole moments of the τ lepton

This is the authors' abstract. We don't add key points for this paper.

Using the data collected by the L3 experiment at LEP from 1991 to 1995 at energies around the Z mass, a measurement of the weak anomalous magnetic dipole moment, a w τ , and of the weak electric dipole moment, d w τ , of the τ lepton is performed. These quantities are obtained from angular distributions in e + e − →τ + τ − →h + ν ̄ τ h − ν τ , where h is a π or a ρ . The results are: Re ( a w τ )=(0.0±1.6±2.3)×10 −3 , Im ( a w τ )=(−1.0±3.6±4.3)×10 −3 and Re ( d w τ )=(−0.44±0.88±1.33)×10 −17 e ·cm. This is the first direct measurement of a w τ .