Speaker
Description
We consider lepton flavor violating transitions mediated by the diphoton effective interaction $\ell\ell'\gamma\gamma$ and explore which processes can probe it better. Our analysis includes single and double radiative decays, $\ell\to\ell'\gamma(\gamma)$, as well as $\ell\to\ell'$ conversions in nuclei for all possible flavor combinations. We find that using the current upper bounds on the rate for $\ell\to\ell'\gamma$, we can derive model-independent upper limits on the rates for $\ell\to\ell'\gamma\gamma$. We conclude that currently, the best limits for the diphoton effective operators provides from the $\ell\to\ell'\gamma$ process, while the best future sensitivities are from $\mu\to e$ conversion in aluminum and potential $\tau\to\ell\gamma(\gamma)$ searches at Belle II or a Super Tau Charm Facility.