The MiniBooNE anomaly, the decay Ds -> mu+nu and heavy sterile neutrino

Understand

It has been recently suggested that the anomalous excess of low-energy electron-like events observed by the MiniBooNE experiment, could be explained by the radiative decay of a heavy sterile neutrino nu_h of the mass around 500 MeV with a muonic mixing strength in the range |U_{\mu h}|^2 \simeq (1-4)\times 10^{-3}.

• If such nu_h exists its admixtures in the decay Ds -> mu+nu would result in the decay Ds -> mu+nu_h with the branching fraction \simeq (1.2-5.5)\times 10^{-4}, which is in the experimentally accessible range.
• Interestingly, the existence of the Ds -> mu+nu_h decay at this level may also explain why the currently measured decay rate of Ds -> mu+nu is slightly higher than the predicted one.
• This enhances motivation for a sensitive search for this decay mode and makes it interesting and complementary to neutrino experiments probing sterile-active neutrino mixing.