Left-right symmetric model for neutrino masses, baryon asymmetry, and dark matter

In the left-right symmetric models without bi-doublet Higgs scalars, the standard model fermions can obtain masses by integrating out heavy charged singlet fermions. We find the decays of heavy neutral singlet fermions, responsible for generating small neutrino masses, can simultaneously produce a left-handed lepton asymmetry for baryon asymmetry and a relic density of right-handed neutrinos for dark matter. Benefiting from the left-right symmetry, the properties of dark matter can be related to the generation of neutrino masses and baryon asymmetry. We also indicate that the decays of the nonthermally produced right-handed neutrinos can explain the observed fluxes of 511 keV photons from the Galactic bulge.