More lepton flavor violating observables for LHCb's run 2

The RKRK measurement by LHCb suggests non-standard lepton non-universality (LNU) to occur in b→sℓ+ℓ−b→sℓ+ℓ− transitions, with effects in muons rather than electrons. A number of other measurements of b→sℓ+ℓ−b→sℓ+ℓ− transitions by LHCb and B  -factories display disagreement with the SM predictions and, remarkably, these discrepancies are consistent in magnitude and sign with the RKRK effect. Non-standard LNU suggests non-standard lepton flavor violation (LFV) as well, for example in B→Kℓℓ′B→Kℓℓ′ and Bs→ℓℓ′Bs→ℓℓ′. There are good reasons to expect that the new effects may be larger for generations closer to the third one. In this case, the Bs→μeBs→μe decay may be the most difficult to reach experimentally. We propose and study in detail the radiative counterpart of this decay, namely Bs→μeγBs→μeγ, whereby the chiral-suppression factor is replaced by a factor of order α/πα/π. A measurement of this mode would be sensitive to the same physics as the purely leptonic LFV decay and, depending on experimental efficiencies, it may be more accessible. A realistic expectation is a factor of two improvement in statistics for either of the Bd,sBd,s modes.