Precision tests via radiative $\hat{I}¼$ and $\ddot{I}„$ leptonic decays

Abstract

The branching fractions of radiative leptonic $\ddot{I}„$ decays $(\ddot{I}„\to l\hat{I}½\bar{\hat{I}}½{\hat{I}}^3$, $l=e,\hat{I}¼)$ were recently measured by the Babar collaboration with a relative error of about 3%. The measurement of the branching ratio $\mathcal{B}(\ddot{I}„\to e\bar{\hat{I}}½\hat{I}½{\hat{I}}^3)$, for a minimum photon energy of 10 MeV in the $\ddot{I}„$ rest frame, differs from our recent SM prediction by 3.5 standard deviations, whereas our result agrees with Babar's value for $\mathcal{B}(\ddot{I}„\to \hat{I}¼\bar{\hat{I}}½\hat{I}½{\hat{I}}^3)$. Our predictions also agree with the measurement of $\mathcal{B}(\hat{I}¼\to e\bar{\hat{I}}½\hat{I}½{\hat{I}}^3)$ by the MEG collaboration. We also report on a recent proposal to test the $\ddot{I}„$ dipole moments via precise measurements of radiative leptonic $\ddot{I}„$ decays at high-luminosity $B$ factories.

10 pages, 1 figure, to appear in the proceedings of the 12th International Symposium on Radiative Corrections (Radcor 2015) and LoopFest XIV (Radiative Corrections for the LHC and Future Colliders)