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

Bernat Capdevila, Andreas Crivellin, Sébastien Descotes-Genon, Lars Hofer, Joaquim Matias

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© 2018 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the »» 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.
Original languageEnglish
Article number181802
JournalPhysical Review Letters
Issue number18
Publication statusPublished - 3 May 2018


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