Bounds on the tau magnetic moments: standard model and beyond

Abstract We obtain new bounds for the magnetic dipole moments of the tau lepton. These limits on the magnetic couplings of the tau to the electroweak gauge bosons (γ, W, Z ) are set in a model independent way using the most general effective Lagrangian with the SU (2) L ⊗ U (1) Y symmetry. Comparison with data from the most precise experiments at high energies shows that the present limits are more stringent than the previous published ones. For the anomalous magnetic moment the bounds are, for the first time, within one order of magnitude of the standard model prediction.