Long-lived sterile neutrinos from an axionlike particle at Belle II

2024/10/01 by Zeren Simon Wang, Yu Zhang, Wang, Zeren Simon +3 · 2 citations
Physics and Astronomy · #Astrophysics #Axion #Biology #Dark Matter and Cosmic Phenomena #Dark matter #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph) #Neutrino #Neutrino Physics Research #Neutrino oscillation #Nuclear physics #Particle (ecology) #Particle physics #Particle physics theoretical and experimental studies #Physics #Sterile neutrino

paper · pdf · doi:10.48550/arxiv.2410.00491

published in arXiv (Cornell University) (Cornell University)

openalex publication_date 2024/10/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Axionlike particles (ALPs) can be produced in meson decays via tree-level quark-flavor-violating couplings, and decay to a pair of sterile neutrinos if also coupled to them. Such light sterile neutrinos are necessarily long-lived and may give rise to striking signatures of displaced vertices (DVs) at terrestrial experiments. In this work, we study the prospect of the ongoing Belle II experiment for detecting the sterile neutrinos from the ALP, leveraging the O(10¹⁰) B-mesons projected to be produced at the experiment with an integrated luminosity of 50 ab^-1. We propose search strategies for one or two DVs, and perform Monte-Carlo simulations in order to estimate the sensitivity reach of Belle II to active-sterile-neutrino mixing |V_eN|² as functions of the sterile-neutrino mass. Signatures include a selected list of sterile-neutrino final states, for which we estimate an O(1) or lower background level. Our results show that the proposed search strategies can probe values of |V_eN|² up to about two orders of magnitude beyond the existing bounds, for ALP mass over 4 GeV and sterile-neutrino mass above the D-meson threshold. Compared to the one-DV search, the two-DV one, despite its weaker sensitivities as a result of double exponential suppression of the sterile-neutrino decay positions, possesses the advantage of possible full reconstruction of the signal event allowing for pinning down the masses of the sterile neutrino and the ALP, if a discovery is made.

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• Long-Lived HNLs via ALP Portal at the LHC
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Related

• Long-lived sterile neutrinos from axionlike particles at the Super Tau-Charm Facility
• Discovery potential of light sterile neutrinos with displaced vertices
• Light sterile neutrino searches
• Displaced vertex searches for sterile neutrinos at future lepton colliders
• Search for sterile neutrinos by shower events at a future neutrino telescope