Solutions to the MiniBooNE Anomaly from New Physics in Charged Meson Decays

We point out that production of new bosons by charged meson decays can greatly enhance the sensitivity of beam-focused accelerator-based experiments to new physics signals. This enhancement arises since the charged mesons are focused and their three-body decays do not suffer from helicity suppression in the same way as their usual two-body decays. As a realistic application, we attempt to explain the MiniBooNE low energy excess utilizing this overlooked mechanism, uniquely realizing dark-sector interpretations as plausible solutions to the excess. As proof of the principle, we consider two well-motivated classes of dark-sector models, models of vector-portal dark matter and models of long-lived (pseudo)scalar. We argue that the model parameter values to accommodate the excess are consistent with existing limits and that they can be tested at current and future accelerator-based neutrino experiments.

A Light Mediator Relating Neutrino Reactions

The extension of the standard model with a multiplicative U(1)R factor is consistent with a light vector boson. In its simplest realization, only right-handed particles carry charges of the new group. In this model, there is a residual τ3R symmetry and one new coupling constant which correlates neutrino interactions. We compute new contributions to antineutrino–electron scattering and coherent scattering on nuclei, and compare them with the XENON1T result.