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 polarization 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.