Beyond the Low Energy Approximation in Braneworld Cosmology

TL;DR

This paper develops an advanced four-dimensional effective theory for Randall-Sundrum braneworld models, enabling detailed analysis of perturbations beyond traditional approximations, including high-energy inflation and observational distinctions from standard cosmology.

Contribution

It introduces a formalism that incorporates higher derivative corrections and extends perturbation analysis beyond the slow-velocity regime in braneworld cosmology.

Findings

Analyzed scalar and tensor perturbations in high-energy braneworld inflation.

Identified observational signatures distinguishing braneworlds from standard inflation.

Compared inflation and cyclic models in the context of higher-order corrections.

Abstract

We develop a four-dimensional effective theory for Randall-Sundrum models which allows us to calculate long wavelength adiabatic perturbations in a regime where the $\rho ^2$ terms characteristic of braneworld cosmology are significant. This extends previous work employing the moduli space approximation. We extend the treatment of the system to include higher derivative corrections present in the context of braneworld cosmology. The developed formalism allows us to study perturbations beyond the general long wavelength, slow-velocity regime to which the usual moduli approximation is restricted. It enables us to extend the study to a wide range of braneworld cosmology models for which the extra terms play a significant role. As an example we discuss high energy inflation on the brane and analyze the key observational features that distinguish braneworlds from ordinary inflation by considering scalar and tensor perturbations as well as non-gaussianities. We also compare inflation and Cyclic models and study how they can be distinguished in terms of these corrections.