Axino Dark Matter from Q-Balls in Affleck-Dine Baryogenesis and the Ω_b — Ω_(DM) Coincidence Problem

摘要

We show that the Ω_b — Ω_(DM) coincidence can naturally be explained in a framework where axino is cold dark matter which is predominantly produced in nonthermal processes involving decays of Q-balls formed in Affleck-Dine baryogenesis. In this approach, the similarity of Ω_b and Ω_(DM) is a direct consequence of the (sub-)GeV scale of the mass of the axino, while the reheating temperature T_R must be low, some 10~2 GeV, or less.