UVprotected (natural) inflation: primordial fluctuations and nongaussian features
Abstract
We consider the UVprotected inflation, where the inflaton potential is obtained by quantum (oneloop) breaking of a global symmetry into a discrete symmetry. In this model, all coupling scales are subPlanckian. This is achieved by coupling the inflaton kinetic term to the Einstein tensor such that the friction is enhanced gravitationally at high energies. In this respect, this new interaction makes virtually any potential adequate for inflation while keeping the system perturbative unitary. We show that even if the gravitationally enhanced friction intrinsically contains new nonlinearities, the UVprotected inflation (and any similar models) behaves as a single field scenario with red tilted spectrum and potentially detectable gravitational waves. Interestingly enough, we find that nonGaussianity of the curvature perturbations in the local form are completely dominated by the nonlinear gauge transformation from the spatially flat to uniformfield gauge and/or by parity violating interactions of the inflaton and gauge bosons. In particular, the parity violating interactions may produce detectable nonGaussianity.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 July 2011
 DOI:
 10.1088/14757516/2011/07/031
 arXiv:
 arXiv:1106.0502
 Bibcode:
 2011JCAP...07..031G
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 typos in equation (7.22) fixed