The XENON1T collaboration recently reported an excess in electron recoil events in the energy range between 1–7 keV. This excess could be understood to originate from the known solar neutrino flux if neutrinos couple to a light vector mediator with strength $g_{\nu N}$ that kinetically mixes with the photon with strength $\chi$ and $g_{\nu N}\chi \sim {10}^{-13}$. Here, we show that such coupling values can naturally arise in a renormalizable model of long-range vector-mediated neutrino self-interactions. The model could be distinguished from other explanations of the XENON1T excess by the characteristic $1/T^2$ energy dependence of the neutrino-electron scattering cross section. Other signatures include invisible Higgs and $Z$ decays and leptophilic charged Higgses at a few 100 GeV. ALPS II will probe part of the viable parameter space.

• Received 23 June 2020
• Accepted 9 September 2020

DOI:https://doi.org/10.1103/PhysRevLett.125.161802

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Published by the American Physical Society