Coleman-Weinberg inflation in light of Planck

Abstract

We revisit a single field inflationary model based on Coleman-Weinberg potentials. We show that in small field Coleman-Weinberg inflation, the observed amplitude of perturbations needs an extremely small quartic coupling of the inflaton, which might be a signature of radiative origin. However, the spectral index obtained in a standard cosmological scenario turns out to be outside the 2. σ region of the Planck data. When a non-standard cosmological framework is invoked, such as brane-world cosmology in the Randall-Sundrum model, the spectral index can be made consistent with Planck data within 1. σ, courtesy of the modification in the evolution of the Hubble parameter in such a scheme. We also show that the required inflaton quartic coupling as well as a phenomenologically viable B - L symmetry breaking together with a natural electroweak symmetry breaking can arise dynamically in a generalized B - L extension of the Standard Model where the full potential is assumed to vanish at a high scale. © 2014 The Authors.