Impact of Hadronic Resonances on $B\to K^{(*)}τ^+τ^-$ decays
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| Autores principales: | , , , , |
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| Formato: | Preprint |
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2026
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| _version_ | 1866917516792561664 |
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| author | Baltà, Guillermo Crivellin, Andreas Escribano, Rafel Matias, Joaquim Novoa-Brunet, Martín |
| author_facet | Baltà, Guillermo Crivellin, Andreas Escribano, Rafel Matias, Joaquim Novoa-Brunet, Martín |
| contents | Neutral-current semileptonic $B$ decays are plagued by hadronic resonances across the dilepton invariant-mass squared spectrum, $q^2$. For light leptons, $\ell=e,μ$, these resonances can be avoided with suitable $q^2$ cuts. This strategy is less straightforward for $τ$ modes, where missing energy from the $τ$ decay makes $q^2$ difficult to reconstruct. In fact, while Belle II is able to discriminate between different regions in $q^2$ due to its clean environment, this is not directly possible in a hadronic one. Therefore, the interpretation of $b\to sτ^+τ^-$ measurements from e.g. LHCb, CMS requires the description of these resonant effects. In this article, we adopt a different strategy by including the resonant contributions (in particular from $ψ(2S)$) into our predictions for $B\to K^{(*)}τ^+τ^-$ decays, instead of avoiding them. We provide predictions for different initial kinematic points ($4m_τ^2, 14.18\,$GeV$^2$ and $15\,$GeV$^2$) that can be convenient for LHCb, CMS and Belle II. For this, we use a data-driven approach based on the LHCb measurements of $B\to K^{(*)}μ^+μ^-$ decays. Including the resonances and integrating over the full $q^2$ range substantially enhances the Standard Model predictions. However, for sufficiently large New Physics, motivated by the current tensions in $R(D^{(*)})$ and $B\to K^{(*)}νν$ decays, the short-distance contribution becomes comparable to or even exceeds the resonant one. This highlights two advantages of this strategy: it exploits the additional phase space associated with the resonant regions to probe large New Physics contributions, and it enables the use of hadron-collider data, where the resonances cannot be resolved. We further quantify how including or neglecting the resonances affects the total branching ratio as a function of New Physics contributions and, equivalently, of the experimental precision. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_21291 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Impact of Hadronic Resonances on $B\to K^{(*)}τ^+τ^-$ decays Baltà, Guillermo Crivellin, Andreas Escribano, Rafel Matias, Joaquim Novoa-Brunet, Martín High Energy Physics - Phenomenology High Energy Physics - Experiment High Energy Physics - Lattice Neutral-current semileptonic $B$ decays are plagued by hadronic resonances across the dilepton invariant-mass squared spectrum, $q^2$. For light leptons, $\ell=e,μ$, these resonances can be avoided with suitable $q^2$ cuts. This strategy is less straightforward for $τ$ modes, where missing energy from the $τ$ decay makes $q^2$ difficult to reconstruct. In fact, while Belle II is able to discriminate between different regions in $q^2$ due to its clean environment, this is not directly possible in a hadronic one. Therefore, the interpretation of $b\to sτ^+τ^-$ measurements from e.g. LHCb, CMS requires the description of these resonant effects. In this article, we adopt a different strategy by including the resonant contributions (in particular from $ψ(2S)$) into our predictions for $B\to K^{(*)}τ^+τ^-$ decays, instead of avoiding them. We provide predictions for different initial kinematic points ($4m_τ^2, 14.18\,$GeV$^2$ and $15\,$GeV$^2$) that can be convenient for LHCb, CMS and Belle II. For this, we use a data-driven approach based on the LHCb measurements of $B\to K^{(*)}μ^+μ^-$ decays. Including the resonances and integrating over the full $q^2$ range substantially enhances the Standard Model predictions. However, for sufficiently large New Physics, motivated by the current tensions in $R(D^{(*)})$ and $B\to K^{(*)}νν$ decays, the short-distance contribution becomes comparable to or even exceeds the resonant one. This highlights two advantages of this strategy: it exploits the additional phase space associated with the resonant regions to probe large New Physics contributions, and it enables the use of hadron-collider data, where the resonances cannot be resolved. We further quantify how including or neglecting the resonances affects the total branching ratio as a function of New Physics contributions and, equivalently, of the experimental precision. |
| title | Impact of Hadronic Resonances on $B\to K^{(*)}τ^+τ^-$ decays |
| topic | High Energy Physics - Phenomenology High Energy Physics - Experiment High Energy Physics - Lattice |
| url | https://arxiv.org/abs/2605.21291 |