A relation between CP violation of low energy and leptogenesis

CP violation at low energy is observed in K and B system. In the future neutrino oscillation experiments , CP asymmetry of the neutrino oscillations P (νi → νj) 6= P (ν̄i → ν̄j) may be also measured. Our question is how low energy CP violation measurements are related to CP violation for Baryon number asymmetry. Fukugita and Yanagida proposed a scenario for Baryon number asymmetry based on the seesaw model.[1] In their scenario, heavy Majorana neutrinos decays give rise to lepton number asymmetry. The asymmetry is converted into Baryon number through spharelon process. [2] In this scenario, CP violating phases in the seesaw model contribute to both CP violation at low energy and CP violation for lepton number asymmetry. However, this correlation is not trivial. This is partly because there are six independent CP violating phases in the seesaw model and the low energy CP violating observables are just three phases of them. It can be shown that three of the six CP violating sources may contribute to the lepton number asymmetry.[3] We can ask the following question. If CP asymmetry of the neutrino oscillations P (νi → νj) 6= P (ν̄i → ν̄j) is measured, what does it mean about CP violation for leptogenesis. To answer to this question, we must first identify the number of the independent CP violating phases and find which of them contributes to leptogenesis and to neutrino oscillations. The plan of my talk is following. We first review the counting of CP phases in the minimal seesaw model and explicitly construct a parameterization. Then we identify the phases in leptogenesis and CP violation in low energy. Finally we give a specific scenario in which both CP violating phenomena has a correlation.