Explaining the MiniBooNE Excess Through a Mixed Model of Oscillation and Decay

TL;DR

This paper proposes a combined oscillation and decay model to explain the MiniBooNE excess, significantly improving fit quality over previous models and predicting no clear oscillation signature in upcoming experiments.

Contribution

It introduces a novel mixed model of neutrino oscillation and decay that better fits MiniBooNE data than single sterile neutrino models.

Findings

Significant fit improvement with $ ext{Δ} ext{χ}^2$/dof = 19.3/2

Predicted decay coupling of $2.8 imes 10^{-7}$ GeV$^{-1}$

No clear oscillation signature expected in FNAL short baseline program

Abstract

The electron-like excess observed by the MiniBooNE experiment is explained with a model comprising a new low mass state ($\mathcal{O}(1)$ eV) participating in neutrino oscillations and a new high mass state ($\mathcal{O}(100)$ MeV) that decays to $\nu+\gamma$. Short-baseline oscillation data sets are used to predict the oscillation parameters. Fitting the MiniBooNE energy and scattering angle data, there is a narrow joint allowed region for the decay contribution at 95% CL. The result is a substantial improvement over the single sterile neutrino oscillation model, with $\Delta \chi^2/dof$ = 19.3/2 for a decay coupling of $2.8 \times 10^{-7}$ GeV$^{-1}$, high mass state of 376 MeV, oscillation mixing angle of $7\times 10^{-4}$ and mass splitting of $1.3$ eV$^2$. This model predicts that no clear oscillation signature will be observed in the FNAL short baseline program due to the low signal-level.