Dark matter interpretation of the Super-Kamiokande antineutrino excess in U(1)Lμ−Lτ model
Year: 2026
Type: article
Abstract: Recent Super-Kamiokande analyses of the diffuse supernova neutrino background, based on data across all SK phases, indicate a mild preference over the zero-DSNB hypothesis at the level of about 2.3 σ with electron-like antineutrino events at E ν ¯ e ≃ 20 MeV . We investigate whether all or part of this excess can be accounted for by MeV-scale dark matter annihilation into neutrinos in a U ( 1 ) L μ − L τ model. The dark matter is a Dirac fermion with m χ ≃ 22 MeV that annihilates via a light Z ′ mediator into ν μ ν ¯ μ and ν τ ν ¯ τ , which are partly converted into ν ¯ e through flavor oscillations. We find that this scenario can account for the excess, or a fraction thereof, while reproducing the observed relic abundance via thermal freeze-out. We further discuss the relevant laboratory and cosmological constraints, including neutrino trident production, NA64- μ , Borexino, and the contribution to Δ N eff .
Source: Physics Letters B
Authors: Motoi Endo, Yushi Mura, Tenta Tsuji
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7222785141