Baryogenesis from a Lepton Asymmetric Universe
  We demonstrate that $CP-$violation in the Majorana mass matrices of the heavy neutrinos can generate a $CP-$asymmetric universe. The subsequent decay of the Majorana particles generates a lepton number asymmetry. During the electroweak phase transition the lepton asymmetry is converted into a baryon asymmetry, which survives down to this time. 
Marion Flanz, Emmanuel A. Paschos and Utpal Sarkar