Reheating-temperature independence of cosmological baryon asymmetry in Affleck-Dine leptogenesis

In this paper we point out that the cosmological baryon asymmetry in our universe is generated almost independently of the reheating temperature TR in Affleck-Dine leptogenesis and it is determined mainly by the mass of the lightest neutrino, m_ν₁, in a wide range of reheating temperature TR10⁵--10¹²GeV. The present baryon asymmetry predicts the m_ν₁ in a narrow region m_ν₁(0.1--3)×10^-9eV. Such a small mass of the lightest neutrino leads to a high predictability on the mass parameter m_νₑνₑ contributing to the neutrinoless double beta decay. We also propose an explicit model in which such an ultralight neutrino can be naturally obtained.