Nonthermal leptogenesis with strongly hierarchical right-handed neutrinos

Assuming the Dirac-type neutrino masses m(D) are related to quark or charged lepton masses, neutrino oscillation data indicate that right-handed neutrino masses are in general strongly hierarchical. In particular, if m(D) is similar to the up-type quark masses, the mass of the lightest right-handed neutrino M-1 less than or similar to 10(6) GeV. We show that nonthermal leptogenesis by inflaton decay can yield sufficient baryon asymmetry despite this constraint, and discuss how the asymmetry is correlated with the low energy neutrino masses and CP-violating phases.