Simple inflationary models in Gauss-Bonnet brane-world cosmology

TL;DR

This paper investigates how Gauss-Bonnet brane-world cosmology alters inflationary predictions for the CMB, notably suppressing tensor perturbations, and discusses how future measurements can distinguish this model from others.

Contribution

It introduces the impact of Gauss-Bonnet effects on inflationary predictions, contrasting them with standard and Randall-Sundrum models, and explores observational tests.

Findings

Tensor perturbation spectrum is suppressed in Gauss-Bonnet brane-world.

Inflationary predictions for spectral index and tensor-to-scalar ratio are significantly modified.

The model can be distinguished from other brane-world scenarios through future CMB observations.

Abstract

In light of the recent Planck 2015 results for the measurement of the CMB anisotropy, we study simple inflationary models in the context of the Gauss-Bonnet brane-world cosmology. The brane-world cosmological effect modifies the power spectra of scalar and tensor perturbations generated by inflation and causes a dramatic change for 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 power spectrum of tensor perturbation is suppressed due to the Gauss-Bonnet brane-world cosmological effect, which is in sharp contrast with inflationary scenario in the Randall-Sundrum brane-world cosmology where the power spectrum is enhanced. Hence, these two brane-world cosmological scenarios are distinguishable. With the dramatic change of the inflationary predictions, the inflationary scenario in the Gauss-Bonnet brane-world cosmology can be tested by more precise measurements of $n_s$ and future observations of the CMB $B$-mode polarization.