The Subdominant Curvaton
  We present a systematic study of the amplitude of the primordial perturbation
in curvaton models with self-interactions, treating both renormalizable and
non-renormalizable interactions. In particular, we consider the possibility
that the curvaton energy density is subdominant at the time of the curvaton
decay. We find that large regions in the parameter space give rise to the
observed amplitude of primordial perturbation even for non-renormalizable
curvaton potentials, for which the curvaton energy density dilutes fast. At the
time of its decay, the curvaton energy density may typically be subdominant by
a relative factor of 10^-3 and still produce the observed perturbation. Field
dynamics turns out to be highly non-trivial, and for non-renormalizable
potentials and certain regions of the parameter space we observe a
non-monotonous relation between the final curvature perturbation and the
initial curvaton value. In those cases, the time evolution of the primordial
perturbation also displays an oscillatory behaviour before the curvaton decay.
