Explaining the MiniBooNE excess through a mixed model of neutrino oscillation and decay

The electronlike excess observed by the MiniBooNE experiment is explained with a model comprising a new low mass state (O(1) eV) participating in neutrino oscillations and a new high mass state (O(100) MeV) that decays to nu + gamma. Short-baseline oscillation datasets 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 x 10(-7) GeV-1, high mass state of 376 MeV, oscillation mixing angle of 7 x 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.