Insights on the current semi-leptonic $B$-decay discrepancies -- and how $B_s \to μ^+ μ^- γ$ can help
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| Format: | Preprint |
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2023
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| _version_ | 1866914625392476160 |
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| author | Guadagnoli, Diego Normand, Camille Simula, Silvano Vittorio, Ludovico |
| author_facet | Guadagnoli, Diego Normand, Camille Simula, Silvano Vittorio, Ludovico |
| contents | $B_s \to μ^+ μ^- γ$, measured at high $q^2$ as a partially reconstructed decay, can probe the origin of the existing discrepancies in semi-leptonic $b \to s$ and $b \to c$ 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, $B_s \to μ^+ μ^- γ$ 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 $q^2$. After quantifying to the best of our knowledge the $B_s \to μ^+ μ^- γ$ experimental over the long haul, we infer the $B_s \to μ^+ μ^- γ$ sensitivity to the couplings relevant to the anomalies. In the example of the real-$δC_{9,10}$ scenario, we find significances below 3$σ$. 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 $q^2$, and not affected by long-distance issues such as narrow resonances or intermediate charmed di-meson rescattering. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2308_00034 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Insights on the current semi-leptonic $B$-decay discrepancies -- and how $B_s \to μ^+ μ^- γ$ can help Guadagnoli, Diego Normand, Camille Simula, Silvano Vittorio, Ludovico High Energy Physics - Phenomenology High Energy Physics - Experiment High Energy Physics - Lattice $B_s \to μ^+ μ^- γ$, measured at high $q^2$ as a partially reconstructed decay, can probe the origin of the existing discrepancies in semi-leptonic $b \to s$ and $b \to c$ 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, $B_s \to μ^+ μ^- γ$ 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 $q^2$. After quantifying to the best of our knowledge the $B_s \to μ^+ μ^- γ$ experimental over the long haul, we infer the $B_s \to μ^+ μ^- γ$ sensitivity to the couplings relevant to the anomalies. In the example of the real-$δC_{9,10}$ scenario, we find significances below 3$σ$. 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 $q^2$, and not affected by long-distance issues such as narrow resonances or intermediate charmed di-meson rescattering. |
| title | Insights on the current semi-leptonic $B$-decay discrepancies -- and how $B_s \to μ^+ μ^- γ$ can help |
| topic | High Energy Physics - Phenomenology High Energy Physics - Experiment High Energy Physics - Lattice |
| url | https://arxiv.org/abs/2308.00034 |