Seesaw scale and CP phases in a minimal model of leptogenesis

The seesaw mechanism to derive the light masses of left-handed neutrinos using heavy masses of right-handed neutrinos gives rise to a connection between low-energy measurables and Grand Unified Theory (GUT)-scale mechanism. We express the neutrino mixing angles in terms of a single variable sin θ13, whose size was measured recently. The lepton asymmetry from the decays of heavy neutrinos via Yukawa coupling is described by CP phases in both Dirac and Majorana type. It is shown that the seesaw scale relevant to the lepton asymmetry can be constrained by CP phase in this minimal model.