A solution to the baryon and dark-matter coincidence puzzle in a $\tilde{N}$ dominated early universe

If a bosonic partner of a right-handed neutrino dominates the early universe sufficiently before its decay, important ingredients in the present universe are related to physics of the right-handed neutrino sector. In particular, we find that the ratio of the baryon to the dark-matter densities is given only by low-energy parameters such as a neutrino mass and a gravitino mass if the reheating temperature of inflation is much higher than 10 12 GeV. Here, the gravitino is assumed to be the lightest supersymmetric particle and the dominant component of the dark matter. The observed ratio, Ω B / Ω DM ≃ 0 . 21 ± 0 . 04, suggests the mass of the gravitino to be in the range of O (10) MeV provided the CP violating phase is of the order 1.