Improved Bounds on the Electromagnetic Dipole Moments of the Tau Lepton
  Using electroweak data and an effective Lagrangian approach we obtain stringent bounds on the tau anomalous magnetic moment, $-0.004 \leq a_\tau \leq 0.006$, and on its electric dipole moment, $|d_\tau| \leq 1.1 \times 10^{-17} e$ cm. This significantly improves our previous bounds. With the same method, we obtain limits on the dipole moments of other fermions. 
Rafel Escribano, Eduard Masso