Source of CP Violation for the Baryon Asymmetry of the Universe
  We give a description of why the existence of a fourth generation is likely to provide enough CP violation for baryogenesis, and trace how this observation came about. We survey the current experimental and theoretical pursuits and outline a research agenda, touching upon unitarity violation and very heavy chiral quarks, and comment on how the electroweak phase transition picture might be altered. 
George W.S. Hou
hep-ph