Searching for New Physics with b →sτ+τ- Processes

© 2018 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP 3 . In recent years, intriguing hints for the violation of lepton flavor universality (LFU) have been accumulated in semileptonic B decays, both in the charged-current transitions b→c-ν (i.e., RD, RD∗, and RJ/ψ) and the neutral-current transitions b→s+- (i.e., RK and RK∗). Hints for LFU violation in RD(∗) and RJ/ψ point at large deviations from the standard model (SM) in processes involving tau leptons. Moreover, LHCb has reported deviations from the SM expectations in b→sμ+μ- processes as well as in the ratios RK and RK∗, which together point at new physics (NP) affecting muons with a high significance. These hints for NP suggest the possibility of huge LFU-violating effects in b→sτ+τ- transitions. In this Letter, we predict the branching ratios of B→Kτ+τ-, B→K∗τ+τ-, and Bs→φτ+τ-, taking into account NP effects in the Wilson coefficients C9(′)ττ and C10(′)ττ. Assuming a common NP explanation of RD, RD(∗), and RJ/ψ, we show that a very large enhancement of b→sτ+τ- processes, of around 3 orders of magnitude compared to the SM, can be expected under fairly general assumptions. We find that the branching ratios of Bs→τ+τ-, Bs→φτ+τ-, and B→K(∗)τ+τ- under these assumptions are in the observable range for LHCb and Belle II.