The baryon-dark matter ratio via moduli decay after Affleck-Dine baryogenesis

Abstract

Low-scale supersymmetry breaking in string motivated theories implies the presence of ##IMG## [http://ej.iop.org/icons/Entities/calO.gif] {Script O} (100 TeV) scale moduli, which generically lead to a significant modification of the history of the universe prior to Big Bang Nucleosynthesis. Such an approach implies a non-thermal origin for dark matter resulting from scalar decay, where the lightest supersymmetric particle can account for the observed dark matter relic density. We study the further effect of the decay on the baryon asymmetry of the universe, and find that this can satisfactorily address the problem of the over-production of the baryon asymmetry by the Affleck-Dine mechanism in the MSSM. Remarkably, there is a natural connection between the baryon and dark matter abundances today, which leads to a solution of the `Cosmic Coincidence Problem'.