Inflation in scale-invariant theories of gravity
  Thanks to the Planck Collaboration, we know the value of the scalar spectral
index of primordial fluctuations with unprecedented precision. In addition, the
joint analysis of the data from Planck, BICEP2, and KEK has further constrained
the value of the tensor-to-scalar ratio $r$ so that chaotic inflationary
scenarios seem to be disfavoured. Inspired by these results, we look for a
model that yields a value of $r$ that is larger than the one predicted by the
Starobinsky model but is still within the new constraints. We show that purely
quadratic, renormalizable, and scale-invariant gravity, implemented by
loop-corrections, satisfies these requirements.
