Simple brane-world inflationary models: an update

TL;DR

This paper updates simple inflationary models within Randall-Sundrum brane-world cosmology, showing how extra-dimensional effects modify inflation predictions and can reconcile models with Planck 2015 data by adjusting the five-dimensional Planck mass.

Contribution

It provides an analysis of how brane-world effects alter inflationary predictions and establishes bounds on the five-dimensional Planck mass to fit observational data.

Findings

Brane-world effects enhance the tensor-to-scalar ratio.

Lower bounds on the five-dimensional Planck mass are derived.

Some inflation models can be made consistent with Planck data through brane effects.

Abstract

In the light of the Planck 2015 results, we update simple inflationary models based on the quadratic, quartic, Higgs and Coleman-Weinberg potentials in the context of the Randall-Sundrum brane-world cosmology. Brane-world cosmological effect alters the inflationary predictions of the spectral index ($n_s$) and the tensor-to-scalar ratio ($r$) from those obtained in the standard cosmology. In particular, the tensor-to-scalar ratio is enhanced in the presence of the 5th dimension. In order to maintain the consistency with the Planck 2015 results for the inflationary predictions in the standard cosmology, we find a lower bound on the five-dimensional Planck mass ($M_5$). On the other hand, the inflationary predictions laying outside of the Planck allowed region can be pushed into the allowed region by the brane-world cosmological effect with a suitable choice of $M_5$.