Probing Lepton Flavour Universality with $Λ_b$ decays to $τ^+τ^-$ final states
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arXiv
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| Autori principali: | , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866911620566876160 |
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| author | Bordone, Marzia Isidori, Gino Mayer, Christiane Toelstede, Jan-Niklas |
| author_facet | Bordone, Marzia Isidori, Gino Mayer, Christiane Toelstede, Jan-Niklas |
| contents | We present a study of the rare baryonic decay $Λ_b \to Λτ^+ τ^-$ as a probe of new physics (NP) coupled preferentially to third-generation fermions. Within the Standard Model, we evaluate the branching ratio and the lepton-flavour-universality (LFU) ratio $R_Λ^{τ/μ}$, including both perturbative and long-distance charm contributions. We show that the LFU ratio can be predicted with an uncertainty below 10%. Possible NP effects arising from lepton non-universal dynamics are analysed within an effective field theory framework motivated by the current anomalies in $b \to cτν$ and $b \to sμ^+μ^-$ transitions. In this context, $R_Λ^{τ/μ}$ can be enhanced by several orders of magnitude, offering a clear target for upcoming searches. The implications for the related mode $Λ_b \to pKτ^+τ^-$ are also briefly discussed. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_05654 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Probing Lepton Flavour Universality with $Λ_b$ decays to $τ^+τ^-$ final states Bordone, Marzia Isidori, Gino Mayer, Christiane Toelstede, Jan-Niklas High Energy Physics - Phenomenology We present a study of the rare baryonic decay $Λ_b \to Λτ^+ τ^-$ as a probe of new physics (NP) coupled preferentially to third-generation fermions. Within the Standard Model, we evaluate the branching ratio and the lepton-flavour-universality (LFU) ratio $R_Λ^{τ/μ}$, including both perturbative and long-distance charm contributions. We show that the LFU ratio can be predicted with an uncertainty below 10%. Possible NP effects arising from lepton non-universal dynamics are analysed within an effective field theory framework motivated by the current anomalies in $b \to cτν$ and $b \to sμ^+μ^-$ transitions. In this context, $R_Λ^{τ/μ}$ can be enhanced by several orders of magnitude, offering a clear target for upcoming searches. The implications for the related mode $Λ_b \to pKτ^+τ^-$ are also briefly discussed. |
| title | Probing Lepton Flavour Universality with $Λ_b$ decays to $τ^+τ^-$ final states |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2511.05654 |