CPViolation in Neutrino Oscillation and Leptogenesis

We study the correlation between $CP$ violation in neutrino oscillations and leptogenesis in the framework with two heavy Majorana neutrinos and three light neutrinos. Among three unremovable $CP$ phases, a heavy Majorana phase contributes to leptogenesis. We show how the heavy Majorana phase contributes to Jarlskog determinant $J$ as well as neutrinoless double $\beta$ decay by identifying a low energy $CP$-violating phase which signals the $CP$-violating phase for leptogenesis. For some specific cases of the Dirac mass term of neutrinos, a direct relation between lepton number asymmetry and $J$ is obtained. We also study the effect coming from the phases which are not related to leptogenesis.