Quasi-Sterile Neutrinos from Dark Sectors I. BSM matter effects in neutrino oscillations and the short-baseline anomalies

TL;DR

This paper explores how dark sector interactions can produce quasi-sterile neutrinos that modify neutrino oscillations, potentially explaining short-baseline anomalies like MiniBooNE and LSND while remaining consistent with other experiments.

Contribution

It introduces a model of quasi-sterile neutrinos arising from dark sectors that can cause resonant oscillations, offering a new explanation for short-baseline neutrino anomalies.

Findings

Model explains MiniBooNE and LSND anomalies

Compatible with long-baseline reactor and accelerator data

Potentially consistent with MicroBooNE results

Abstract

Quasi-sterile neutrinos are a natural consequence of dark sectors interacting with the Standard Model (SM) sector via neutrino- and vector-portals. Essentially, quasi-sterile neutrinos are light dark sector fermions with two generic properties: (i) they mix with the active neutrinos of the SM, and (ii) they are charged under a vector mediator that couples feebly to SM matter. Various interesting phenomenological consequences result from this class of particles. In this article, we investigate one such consequence: new, beyond the SM matter effects that can alter in-medium neutrino oscillations. In particular, for special windows of energy and matter densities, active neutrinos can resonantly oscillate into sterile neutrinos. We take advantage of this feature to build a quasi-sterile neutrino model that can explain the MiniBooNE and LSND anomalies, while remaining compatible with observations from long-baseline reactor- and accelerator-based neutrino experiments. This model is also likely compatible with the recent results reported by the MicroBooNE collaboration (albeit we cannot precisely quantify this claim due to a lack of information in MicroBooNE's public data releases to date). Implications for solar neutrinos and $\nu_e$ disappearance searches are also briefly discussed.