Model independent bounds on heavy sterile neutrinos from the angular distribution of $\mathbf{B\to D^*\ellν}$ decays
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| Format: | Preprint |
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2024
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| _version_ | 1866916516365074432 |
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| author | Bernlochner, Florian U. Fedele, Marco Kretz, Tim Nierste, Ulrich Prim, Markus T. |
| author_facet | Bernlochner, Florian U. Fedele, Marco Kretz, Tim Nierste, Ulrich Prim, Markus T. |
| contents | In this paper we study the bounds that can be inferred on New Physics couplings to heavy sterile neutrinos $N$ from the recent measurements performed by the Belle collaboration of the angular analysis of $B\to D^*\ell\barν_\ell$ decays, with $\ell=e,μ$. Indeed, a sterile neutrino $N$ may lead to competing $B\to D^*\ell\bar N$ decays and Belle might have measured an incoherent sum of these two independent channels. After reviewing the theoretical formalism required to describe this phenomenon in full generality, we first perform a bump hunt in the $M_{\rm miss}^2$ Belle distribution to search for evidences of an additional massive neutrino. We found in such a way a small hint at $M_{\rm miss}^2 \sim (350\ {\rm MeV})^2$. However, the Belle angular analysis is sensitive to $N$ masses up to $\mathcal{O}$(50 MeV), preventing us to further inspect this hint. Nevertheless, we study the potential impact of this additional channel in the allowed mass range on the measured angular distributions and extract model-independent bounds on the new-physics couplings which could mediate such an interaction. In particular, in the mass window here inspected, we obtain the most stringent bounds for vector and left-handed scalar operators to date. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2410_11945 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Model independent bounds on heavy sterile neutrinos from the angular distribution of $\mathbf{B\to D^*\ellν}$ decays Bernlochner, Florian U. Fedele, Marco Kretz, Tim Nierste, Ulrich Prim, Markus T. High Energy Physics - Phenomenology High Energy Physics - Experiment In this paper we study the bounds that can be inferred on New Physics couplings to heavy sterile neutrinos $N$ from the recent measurements performed by the Belle collaboration of the angular analysis of $B\to D^*\ell\barν_\ell$ decays, with $\ell=e,μ$. Indeed, a sterile neutrino $N$ may lead to competing $B\to D^*\ell\bar N$ decays and Belle might have measured an incoherent sum of these two independent channels. After reviewing the theoretical formalism required to describe this phenomenon in full generality, we first perform a bump hunt in the $M_{\rm miss}^2$ Belle distribution to search for evidences of an additional massive neutrino. We found in such a way a small hint at $M_{\rm miss}^2 \sim (350\ {\rm MeV})^2$. However, the Belle angular analysis is sensitive to $N$ masses up to $\mathcal{O}$(50 MeV), preventing us to further inspect this hint. Nevertheless, we study the potential impact of this additional channel in the allowed mass range on the measured angular distributions and extract model-independent bounds on the new-physics couplings which could mediate such an interaction. In particular, in the mass window here inspected, we obtain the most stringent bounds for vector and left-handed scalar operators to date. |
| title | Model independent bounds on heavy sterile neutrinos from the angular distribution of $\mathbf{B\to D^*\ellν}$ decays |
| topic | High Energy Physics - Phenomenology High Energy Physics - Experiment |
| url | https://arxiv.org/abs/2410.11945 |