Abstract
B s → μ+μ−γ, measured at high q2 as a partially reconstructed decay, can probe the origin of the existing discrepancies in semi-leptonic b → s and b → c decays. We perform a complete study of this possibility. We start by reassessing the alleged discrepancies, with a focus on a unified EFT description. Using the SMEFT, we find that the tauonic Wilson coefficient required by R(D(*)) implies a universal muonic Wilson coefficient of precisely the size required by semi-muonic BR data and, separately, by semi-muonic angular analyses. We thus identify reference scenarios. Importantly, Bs → μ+μ−γ offers a strategy to access them without being affected by the long-distance issues that hamper the prediction of semi-leptonic B decays at low q2. After quantifying to the best of our knowledge the Bs → μ+μ−γ experimental over the long haul, we infer the Bs → μ+μ−γ sensitivity to the couplings relevant to the anomalies. In the example of the real-δC9,10 scenario, we find significances below 3σ. Such figure is to be compared with other single-observable sensitivities that one can expect from e.g. BR and angular data, whether at low or high q2, and not affected by long-distance issues such as narrow resonances or intermediate charmed di-meson rescattering.
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Acknowledgments
We warmly thank Martino Borsato for useful feedback, and Alexandre Carvunis for help on various aspects of flavio. We are grateful to Francesco Dettori for several discussions and for input related to section 3.1. This work is supported by ANR under contract n. 202650 (ANR-19-CE31-0016, GammaRare).
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Guadagnoli, D., Normand, C., Simula, S. et al. Insights on the current semi-leptonic B-decay discrepancies — and how Bs → μ+μ−γ can help. J. High Energ. Phys. 2023, 102 (2023). https://doi.org/10.1007/JHEP10(2023)102
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DOI: https://doi.org/10.1007/JHEP10(2023)102