tau dipole moments via radiative leptonic tau decays

We propose a new method to probe the magnetic and electric dipole moments of the tau lepton using precise measurements of the differential rates of radiative leptonic tau decays at high-luminosity B factories. Possible deviations of these moments from the Standard Model values are analyzed in an effective Lagrangian approach, thus providing model-independent results. Analytic expressions for the relevant non-standard contributions to the differential decay rates are presented. Earlier proposals to probe the tau dipole moments are examined. A detailed feasibility study of our method is performed in the conditions of the Belle and Belle II experiments at the KEKB and Super-KEKB colliders, respectively. This study shows that our approach, applied to the planned full set of Belle II data for radiative leptonic tau decays, has the potential to improve the present experimental bound on the tau anomalous magnetic moment. On the contrary, its foreseen sensitivity is not expected to lower the current experimental limit on the tau electric dipole moment.