No-Scale Inflation
  Supersymmetry is the most natural framework for physics above the TeV scale,
and the corresponding framework for early-Universe cosmology, including
inflation, is supergravity. No-scale supergravity emerges from generic string
compactifications and yields a non-negative potential, and is therefore a
plausible framework for constructing models of inflation. No-scale inflation
yields naturally predictions similar to those of the Starobinsky model based on
$R + R^2$ gravity, with a tilted spectrum of scalar perturbations: $n_s \sim
0.96$, and small values of the tensor-to-scalar perturbation ratio $r < 0.1$,
as favoured by Planck and other data on the cosmic microwave background (CMB).
Detailed measurements of the CMB may provide insights into the embedding of
inflation within string theory as well as its links to collider physics.
