Abelian dark matter models for 511 keV gamma rays and direct detection
  We construct a simple U(1) hidden sector model of metastable dark matter that
could explain excess 511 keV gamma rays from the galactic center as observed by
INTEGRAL, through inelastic scattering of dark matter followed by its decay.
Although the model is highly constrained, it naturally accommodates dark matter
with mass and cross section in the range suggested by the CoGeNT and CRESST
experiments. The dark gauge boson that mediates the interactions with standard
model matter has a mass of several hundred MeV, and might be discovered by
heavy photon detection experiments, including APEX, MAMI and HPS.
