Primordial tensor modes from quantum corrected inflation

We analyze quantum corrections on the naive φ4 inflation. These typically lead to an inflaton potential which carries a noninteger power of the field. We consider both minimal and nonminimal couplings to gravity. For the latter case we also study unitarity of inflaton-inflaton scattering. Finally we confront these theories with the Planck and BICEP2 data. We demonstrate that the presence of nonvanishing primordial tensor modes requires sizable quantum departures from the φ4-inflation model for the nonminimally coupled scenario which we parametrize and quantify. We compare the results with the minimally coupled case and elucidate the main distinctive features. © 2014 American Physical Society