Successful supersymmetric dark matter with thermal over/under-abundance from late decay of a visible sector scalar
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We present an explicit model where the decay of an R-parity-even scalar S with O(TeV) mass is the origin of nonthermal dark matter. The correct relic abundance can be produced for both large and small annihilation rates in accordance with the Fermi constraints on the annihilation cross section. This scenario has advantages over that of nonthermal dark matter from modulus decay. First, the branching ratio for production of R-parity odd particles can be made quite small by a combination of S couplings to matter fields and kinematic suppression, enabling us to obtain the observed dark matter relic density in cases of thermal underproduction as well as overproduction. Second, gravitino production is naturally suppressed by the virtue of a decaying scalar belonging to the visible sector. The decaying scalar can also successfully generate the baryon asymmetry of the Universe, and may provide an explanation for the baryon - dark matter coincidence puzzle. 2013 American Physical Society.