Scalar perturbations from brane-world inflation with curvature effects

TL;DR

This paper analyzes scalar perturbations during brane-world inflation with curvature corrections, showing that these effects suppress perturbation amplitudes and constraining the model with WMAP7 data.

Contribution

It extends the RS2 brane-world scenario by including Gauss-Bonnet and induced gravity terms, analyzing their impact on inflationary scalar perturbations.

Findings

Scalar perturbation amplitude decreases with curvature corrections.

Gauss-Bonnet effects significantly suppress high-energy perturbations.

Model constraints are derived from WMAP7 data.

Abstract

We consider a generalization of the Randall-Sundrum single brane-world scenario (RS2). More precisely, the generalization is described through curvature corrections, corresponding to a Gauss-Bonnet term in the bulk and a Hilbert-Einstein term, as well as the strength of the induced gravity term, on the brane. We are mainly interested in analyzing the early inflationary era of the brane, which we model within the extreme slow-roll limit, i.e., under a de Sitter like brane inflation, where the inflaton field is confined on the brane. We compute the scalar perturbations in this model and compare our results with those previously obtained for the RS2 scenario with and without an induced gravity term on the brane or a Gauss-Bonnet term in the bulk. The amplitude of the scalar perturbations is decreased as compared with a pure RS2 model. In addition, the effect from the Gauss-Bonnet correction in an induced gravity brane-world model is to decrease the amplitude of the scalar perturbations, and a similar result is obtained for the induced gravity effect in a Gauss-Bonnet brane-world. In general, in the high energy limit the amplitude is highly suppressed by the Gauss-Bonnet effect. Finally, we constrain the model using the latest WMAP7 data.