[Gu, Pei-Hong] Abdus Salam Int Ctr Theoret Phys, I-34014 Trieste, Italy
; [Sarkar, Utpal] Phys Res Lab, Ahmadabad 380009, Gujarat, India
; [Sarkar, Utpal] Washington Univ, Dept Phys, St Louis, MO 63130 USA
; [Sarkar, Utpal] Washington Univ, McDonnell Ctr Space Sci, St Louis, MO 63130 USA
; [Zhang, Xinmin] Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
Dark and baryonic matter contribute comparable energy density to the present universe. The dark matter may also be responsible for the cosmic positron and electron excesses. We connect these phenomena with the Dirac seesaw for neutrino masses. In our model (i) the dark matter relic density is a dark matter asymmetry generated simultaneously with the baryon asymmetry so that we can naturally understand the coincidence between the dark and baryonic matter and (ii) the dark matter mostly decays into the leptons so that its decay can interpret the anomalous cosmic rays with positron and electron excesses.