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

TL;DR

This paper explores the possibility that a heavy sterile neutrino could explain the MiniBooNE anomaly and affect the decay rate of Ds mesons, proposing experimental searches for this decay mode.

Contribution

It introduces the idea that heavy sterile neutrino decay could account for MiniBooNE excess and suggests analyzing existing data for Ds -> mu+nu_h decay to test this hypothesis.

Findings

Branching fraction of Ds -> mu+nu_h estimated at (1.2-5.5)×10^{-4}

Potential explanation for the slight excess in Ds -> mu+nu decay rate

Proposal to search for Ds -> mu+nu_h in existing CLEO-c data

Abstract

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. Considering, as an example the CLEO-c experiment, we suggest to perform a search for the decay Ds -> mu+nu_h with the analysis of existing data. The discrepancy between the measurements and theoretical description of the decay Ds -> tau+nu is also discussed in brief.