A Solution to the Coincidence Puzzle of $\Omega_{B}$ and $\Omega_{DM}$

We show that a class of Affleck--Dine baryogenesis directly relates the observed mass density of baryons, \Omega_{B}, to that of dark matter, \Omega_{DM}. In this scenario, the ratio of baryon to dark matter mass density is solely determined by the low energy parameters, except for an O(0.1) effective CP-violating phase. We find that \Omega_{B}/\Omega_{DM}=O(0.1) with reasonable parameters, which lies surprisingly just in the range of observation. This scenario is totally free from the cosmological gravitino problem, and independent of the detailed history of the Universe as long as it satisfies quite weak constraints.