Anomalies in several short-baseline neutrino oscillation experiments suggest the possible existence of sterile neutrinos at about the eV scale that have appreciable mixing with the three known neutrinos. We find that if such a light sterile neutrino exists, through a combined study of the leptonic decays of μ−, τ−, π−, and K−, some semileptonic decays of τ− and the invisible decay width of the Z boson, it is possible to constrain the relevant mixing matrix elements. Furthermore, we compare the constraints, derived by using the method presented here, with the experimental results obtained from short-baseline neutrino oscillation experiments. We find that a single light sterile neutrino cannot satisfy the existing short-baseline neutrino oscillation constraints and explain the anomalies mentioned above. Along the way we provide a number of experimentally clean observables which can be used to directly study the light sterile neutrino independently of the neutrino oscillation experiments.

• Received 15 September 2018

DOI:https://doi.org/10.1103/PhysRevD.98.115021

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Published by the American Physical Society