MiniBooNE anomaly, the decay Ds+→μ+νμ and heavy sterile neutrino

It has been recently suggested that the anomalous excess of low-energy electronlike events observed by the MiniBooNE experiment could be explained by the radiative decay of a heavy sterile neutrino νh of the mass around 500 MeV with a muonic mixing strength in the range |Uμh|2≅(1-4)x10-3. If such νh exists its admixtures in the decay Ds+→μ+νμ would result in the decay Ds+→μ+νh with the branching fraction Br(Ds+→μ+νh)≅(1.2-5.5)x10-4, which is in the experimentally accessible range. Interestingly, the existence of the Ds+→μ+νh decay at this level may also explain why the currently measured decay rate of Ds+→μ+νμ is slightly higher than the predicted one. This enhances motivation for a search for this decay mode and makes it interesting and complementary to neutrino experiments probing sterile-active neutrino mixing. Our estimates show that the sensitive search could be performed with the analysis of existing data, e.g. from the CLEO-c or another analogous experiment. The discrepancy between the measurements and theoretical description of the decay Ds+→τ+ντ is also briefly discussed.