Cladogenesis: Baryon-dark matter coincidence from branchings in moduli decay

Abstract

We propose late-time moduli decay as the common origin of baryons and dark matter. The baryon asymmetry is produced from the decay of new TeV-scale particles, while dark matter is created from the (chain) decay of $R$-parity odd particles without undergoing any annihilation. The baryon and dark matter abundances are mainly controlled by the dilution factor from moduli decay, which is typically in the range ${10}^{\ensuremath{-}9}--{10}^{\ensuremath{-}7}$. The exact number densities are determined by simple branching fractions from modulus decay, which are expected to be of similar order in the absence of symmetries. This scenario can naturally lead to the observed baryon asymmetry and, for moderate suppression of the two-body decays of the modulus to $R$-parity odd particles, can also yield the correct dark matter abundance for a dark matter mass in the (5--500) GeV range.