The TeV-mass curvaton
  We consider the constraints for a curvaton with mass m ~ 1 TeV and show that
they are not consistent with a purely quadratic potential. Even if the curvaton
self-interactions were very weak, they must be accounted for as they affect the
dynamical evolution of the curvature perturbation. We show that the only
TeV-mass curvaton interaction potential that yields the correct perturbation
amplitude, decays before the dark matter freeze-out, and does not give rise to
non-Gaussian perturbations that are in conflict with the present limits, is
given by V_int= sigma^8/M^4. The decay width of the curvaton should be in the
range Gamma= 10^-15...10^-17 GeV. The model typically predicts large
non-linearity parameters f_NL and g_NL that should be observable by the Planck
satellite. We also discuss various physical possibilities to obtain the
required small curvaton decay rate.
