Decaying Sterile Neutrinos and the Short Baseline Oscillation Anomalies

TL;DR

This paper proposes that the MiniBooNE short baseline neutrino anomaly can be explained by a decaying sterile neutrino model, which also potentially accounts for other neutrino anomalies while satisfying cosmological constraints.

Contribution

It introduces a decaying sterile neutrino model with specific mixing and mass parameters as an alternative explanation for short baseline neutrino anomalies.

Findings

Best fit with sterile neutrino mixing mainly with electron neutrinos

Sterile neutrino mass range between 100 eV and 1 keV

Model can satisfy cosmological constraints with secret interactions

Abstract

The MiniBooNE experiment has observed a significant excess of electron neutrinos in a muon neutrino beam at source-detector distances too short to be compatible with standard neutrino oscillations. The most straightforward explanation for this signal in terms of oscillations between Standard Model neutrinos and a new, sterile, neutrino, is disfavored by null results from experiments looking for muon neutrino disappearance. Here, we discuss the possibility that MiniBooNE data are instead explained by a sterile neutrino that decays quickly back into active neutrinos plus a light boson. The flavor composition of the secondary neutrinos is determined by the sterile neutrino mixing angles, and we show that the data is best explained if the sterile neutrino mixes mostly with electron neutrinos. The preferred range for the mass of the sterile neutrino is between 100 eV and 1 keV. We argue that the model can easily satisfy cosmological constraints because it has the "secret interactions" mechanism built-in. Accommodating in addition to the MiniBooNE anomaly also the LSND, reactor, and gallium anomalies is possible, but in this case the model needs to be extended to avoid cosmological limits.