Adiabatic Density Perturbations and Matter Generation from the Minimal Supersymmetric Standard Model

We propose that the inflaton is coupled to ordinary matter only gravitationally and that it decays into a completely hidden sector. In this scenario both baryonic and dark matter originate from the decay of a flat direction of the minimal supersymmetric standard model, which is shown to generate the desired adiabatic perturbation spectrum via the curvaton mechanism. The requirement that the energy density along the flat direction dominates over the inflaton decay products fixes the flat direction almost uniquely. The present residual energy density in the hidden sector is typically shown to be small.

Figure 1

Evolution of the energy densities in the observable (solid line) and hidden (dotted line) sectors. The subscripts “end,” “RH,” “osc,” “EQ,” and “d” refer to, respectively, the end of inflation, reheating by the inflaton decay creating hidden radiation, the beginning of the flat direction oscillation in $m_{\phi }^2{\phi }^2$ potential, the equality of the energy densities of $\phi$-oscillation and hidden radiation, and the decay of the flat direction to produce ordinary radiation.