Trans-Planckian relics in the scalar to tensor ratio
  The physical properties of our universe at energy scales above the expansion rate during inflation can affect predictions for the ratio between the amplitudes of the primordial scalar and tensor fluctuations. In particular, we study here the effects of a breakdown of a locally Lorentz invariant description of nature at tiny space-time intervals. In some instances, these effects shift the amplitudes by a constant amount, altering the standard relation between this ratio and the slow-roll parameters. More generally, "trans-Planckian" effects introduce a modulation in the primordial power spectra which grows at shorter scales, making the value of the ratio sensitive to the scale at which it is defined. We also present a model where symmetries are broken at horizon scales during inflation. In this case, the power at large scales today could then be suppressed, relative to that at smaller scales. 
Hael Collins (Niels Bohr International Academy)