The Baryon-Dark Matter Ratio Via Moduli Decay After Affleck-Dine Baryogenesis

TL;DR

This work demonstrates that late-time entropy production from decays of heavy moduli can simultaneously dilute an overproduced Affleck-Dine baryon asymmetry and non-thermally generate the correct dark matter abundance via LSPs. By linking the baryon and dark matter yields to modulus parameters such as the reheat temperature $T_R^X$, modulus mass $m_X$, and the AD field amplitude $\phi_0/X_0$, the authors provide a natural explanation for the observed baryon-to-dark-matter ratio. The framework predicts a consistent cosmology with $m_X, m_\phi \sim {\cal O}(50-100)$ TeV and $T_R^X$ around tens of MeV, yielding a baryon density and DM density in agreement with observations, and offering a potential resolution to the cosmic coincidence problem. The results are presented as robust within a class of string-inspired models with stabilized moduli and do not rely on ad hoc additions to MSSM dynamics.

Abstract

Low-scale supersymmetry breaking in string motivated theories implies the presence of 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'.