The flavor of a minimal composite $S_1$ leptoquark and the $b\to cτ\barν$ anomaly
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arXiv
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| Format: | Preprint |
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2023
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| _version_ | 1866929358755594240 |
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| author | Da Rold, Leandro |
| author_facet | Da Rold, Leandro |
| contents | Several experiments have measured a deviation in $B\to D^{(*)}$ semileptonic decays, that point to new physics at the TeV scale violating lepton flavor universality. A scalar leptoquark $S_1$, with a suitable structure of couplings in flavor space, is known to be able to solve this anomaly modifying $b\to cτ\barν$. In the context of composite Higgs models, we consider a theory containing $H$ and $S_1$ as Nambu-Goldstone bosons (NGBs) of a new strongly interacting sector, with ordinary resonances at a scale ${\cal O}(10)$ TeV. Assuming anarchic partial compositeness of the Standard Model (SM) fermions we calculate the potential of the NGBs that is dominated by the fermions of the third generation, we compute $R_{D^{(*)}}$ and estimate the corrections to flavor observables by the presence of $S_1$. We find that the SM spectrum and $m_{S_1}\sim$ TeV can be obtained with a NGB decay constant of order $\sim 5$ TeV. We obtain a robust correlation between the main corrections to $R_{D^{(*)}}$, $B_{K^{(*)}νν}$ and $g_τ/g_μ$, that leads to a sever bound on $R_{D^{(*)}}$, roughly $2σ$ below the experimental value. Besides the bounds on the flavor observables $g_τ^W$, BR$(τ\toμγ)$ and $Δm_{B_s}$ are saturated, with the first one requiring a coupling between resonances $g_*\lesssim 2$, whereas the second one demands $m_{S_1}\gtrsim 1.7$ TeV, up to corrections of ${\cal O}(1)$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2311_04062 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | The flavor of a minimal composite $S_1$ leptoquark and the $b\to cτ\barν$ anomaly Da Rold, Leandro High Energy Physics - Phenomenology High Energy Physics - Experiment Several experiments have measured a deviation in $B\to D^{(*)}$ semileptonic decays, that point to new physics at the TeV scale violating lepton flavor universality. A scalar leptoquark $S_1$, with a suitable structure of couplings in flavor space, is known to be able to solve this anomaly modifying $b\to cτ\barν$. In the context of composite Higgs models, we consider a theory containing $H$ and $S_1$ as Nambu-Goldstone bosons (NGBs) of a new strongly interacting sector, with ordinary resonances at a scale ${\cal O}(10)$ TeV. Assuming anarchic partial compositeness of the Standard Model (SM) fermions we calculate the potential of the NGBs that is dominated by the fermions of the third generation, we compute $R_{D^{(*)}}$ and estimate the corrections to flavor observables by the presence of $S_1$. We find that the SM spectrum and $m_{S_1}\sim$ TeV can be obtained with a NGB decay constant of order $\sim 5$ TeV. We obtain a robust correlation between the main corrections to $R_{D^{(*)}}$, $B_{K^{(*)}νν}$ and $g_τ/g_μ$, that leads to a sever bound on $R_{D^{(*)}}$, roughly $2σ$ below the experimental value. Besides the bounds on the flavor observables $g_τ^W$, BR$(τ\toμγ)$ and $Δm_{B_s}$ are saturated, with the first one requiring a coupling between resonances $g_*\lesssim 2$, whereas the second one demands $m_{S_1}\gtrsim 1.7$ TeV, up to corrections of ${\cal O}(1)$. |
| title | The flavor of a minimal composite $S_1$ leptoquark and the $b\to cτ\barν$ anomaly |
| topic | High Energy Physics - Phenomenology High Energy Physics - Experiment |
| url | https://arxiv.org/abs/2311.04062 |