The minimal curvaton-higgs model
  We present the first full study of the minimal curvaton-higgs (MCH) model,
which is a minimal interpretation of the curvaton scenario with one real scalar
coupled to the standard model Higgs boson. The standard model coupling allows
the dynamics of the model to be determined in detail, including effects from
the thermal background and from radiative corrections to the potential. The
relevant mechanisms for curvaton decay are incomplete non-perturbative decay
(delayed by thermal blocking), followed by decay via a dimension-5
non-renormalisable operator. To avoid spoiling the predictions of big bang
nucleosynthesis, we find the "bare" curvaton mass to be m_\sigma > 8 x 10^4
GeV. To match observational data from Planck there is an upper limit on the
curvaton-higgs coupling g, between 10^-3 and 10^-2, depending on the mass. This
is due to interactions with the thermal background. We find that typically
non-Gaussianities are small but that if fnl is observed in the near future then
m_\sigma < 5 x 10^9 GeV, depending on Hubble scale during inflation. In a
thermal dark matter model, the lower bound on m_\sigma\ can increase
substantially. The parameter space may also be affected once the baryogenesis
mechanism is specified.
