Coleman-Weinberg Inflation in light of Planck

Understand

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 sigma 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 sigma, courtesy of the modification in the evolution of the Hubble parameter in such a scheme.