  The existence of light sterile neutrinos in the eV mass range with relatively
large mixing angles with the active neutrinos has been proposed for a variety
of reasons, including to improve the fit to the LSND and MiniBooNE neutrino
oscillation experiments, and reactor disappearance experiments. In ref. Phys.
Rev. D 84, 053001 (2011), it was shown that neutrino mixing with a heavier
sterile neutrino, in the mass range between 33 eV and several GeV, could
significantly affect and improve the agreement between neutrino oscillation
models with light sterile neutrinos and short baseline experimental results,
allowing for a new source of CP violation in appearance experiments and for
different apparent mixing angles in appearance and disappearance experiments.
However in refs. Phys. Rev. D 86, 033015 (2012) and JHEP 1204, 083 (2012) it
was shown that various collider experiment, supernovae, and cosmological
constraints can eliminate most of the parameter region where such a heavy
sterile neutrino can have a significant effect on neutrino oscillations. In
this paper we consider the effects of allowing a new light scalar in the MeV
mass region, which is a potential dark matter candidate, to interact with the
sterile neutrinos, and show that the resulting model is a consistent theory of
neutrino oscillation anomalies and dark matter which can also potentially
explain the INTEGRAL excess of 511 keV gamma rays in the central region of the
galaxy.
