Mixed Sneutrino Dark Matter and the Ratio

It is known that the cosmological baryon density (Ωb) and dark matter density (Ωdm) have strikingly similar values. However, in most theories of the early Universe, each density is explained by separate dynamics and consequently there is no compelling reason for this observation. In this note, I briefly review a model in which the dark matter species possesses a particle-antiparticle asymmetry. This asymmetry determines both the baryon asymmetry and strongly affects the dark matter density, thus naturally linking Ωb and Ωdm. In these models it is shown that sneutrinos can play the role of such dark matter 1.