Rescuing Quadratic Inflation
  Inflationary models based on a single scalar field $\phi$ with a quadratic
potential $V = \frac{1}{2} m^2 \phi^2$ are disfavoured by the recent Planck
constraints on the scalar index, $n_s$, and the tensor-to-scalar ratio for
cosmological density perturbations, $r_T$. In this paper we study how such a
quadratic inflationary model can be rescued by postulating additional fields
with quadratic potentials, such as might occur in sneutrino models, which might
serve as either curvatons or supplementary inflatons. Introducing a second
scalar field reduces but does not remove the pressure on quadratic inflation,
but we find a sample of three-field models that are highly compatible with the
Planck data on $n_s$ and $r_T$. We exhibit a specific three-sneutrino example
that is also compatible with the data on neutrino mass difference and mixing
angles.
