Dark sector origin of the KOTO and MiniBooNE anomalies

We present a dark sector model that reproduces the KOTO, MiniBooNE and muon anomalous magnetic moment anomalies. The dark sector is comprised of a light scalar singlet S that has a large coupling to a slightly heavier sterile neutrino that mixes with the active neutrinos. The scalar couples to standard model fermions via Yukawa couplings, and to photons via a higher-dimensional coupling. The KOTO signal is a result of the flavor-changing penguin process K-L -> pi S-0 followed by the decay of S to neutrinos. The sterile neutrino produced in neutrino-nucleus scattering at MiniBooNE decays to an active neutrino and S, which decays electromagnetically and creates an event excess at low energies. (C) 2020 The Author(s). Published by Elsevier B.V.