Remarks about the Tensor Mode Detection by the BICEP2 Collaboration and   the Super-Planckian Excursions of the Inflaton Field
  The recent detection by the BICEP2 collaboration of a high level of tensor modes has relevant implications which we briefly discuss in this short note. In particular, the large angle CMB B- mode polarisation seems to imply problematic super-Planckian excursions of the inflaton field. We provide some comments about this point and in particular we stress a natural resolution to it: given our current (and probably future) observational ignorance about the true source of the scalar perturbations, one should abandon the theoretical prejudice that they are associated to the inflaton fluctuations. 
Alex Kehagias, Antonio Riotto
astro-ph.CO gr-qc hep-ph hep-th