Primordial perturbations and inflation in a holography inspired Gauss-Bonnet cosmology

TL;DR

This paper explores a modified gravity model inspired by holographic principles, deriving altered cosmological perturbation spectra and comparing them with observational data, thus offering new insights into early universe dynamics.

Contribution

It introduces a holography-inspired Gauss-Bonnet gravity model and analyzes its impact on primordial perturbations and inflationary predictions.

Findings

Power spectra differ significantly from standard and holographic cosmology.

Predicted spectral index and tensor-to-scalar ratio are tested against Planck data.

Modified Friedmann equations align with holographic cosmology at background level.

Abstract

We consider an action for gravity that, in addition to the Einstein-Hilbert term, contains a function of the Ricci scalar and the Gauss-Bonnet invariant. The specific form of the function considered is motivated by holographic cosmology. At background level the field equations imply modified Friedmann equations of the same form as those in the holographic cosmology. We calculate the cosmological perturbations and derive the corresponding power spectra assuming a general $k$-inflation. We find that the resulting power spectra differ substantially from those obtained in both holographic and standard cosmology. The estimated spectral index and tensor-to-scalar ratio are confronted with the Planck results.