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Abstract

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. Benefited from the left-right symmetry, the properties of the dark matter can be related to the generation of the neutrino masses and the baryon asymmetry. We also indicate that the decays of the non-thermally produced right-handed neutrinos can explain the observed fluxes of 511 keV photons from the Galactic bulge.