It is said that the imbalance of matter versus antimatter in the present universe implies CP violations at very high energy. It seems to me that it most directly implies baryon number nonconservation: If we assume (and I'm not exactly sure why this is a necessary assumption) that immediately after the Big Bang, the universe was electrically neutral (and had zero lepton number, baryon number, etc.), then the fact that the baryon number of the universe is nonzero today means that it's not conserved. But what is the relationship between CP violation and baryon number nonconservation? Can you have one without the other?