Brane-world cosmology

TL;DR

This paper proposes a simple brane-world cosmology model with four key parameters, deriving a modified Friedmann equation that aligns with standard cosmology and introduces new early-universe effects when $Z_2$-symmetry is not assumed.

Contribution

It introduces a novel brane-world cosmology model characterized by four parameters and explores the effects of breaking $Z_2$-symmetry on the universe's evolution.

Findings

The model recovers standard cosmology under certain conditions.

Dropping $Z_2$-symmetry introduces a new early-universe term.

The new term transitions from cosmological constant-like to negative curvature, then rapidly damps.

Abstract

A simple model of the brane-world cosmology has been proposed, which is characterized by four parameters, the bulk cosmological constant, the spatial curvature of the universe, the radiation strength arising from bulk space-time and the breaking parameter of $Z_2$-symmetry. The bulk space-time is assumed to be locally static five-dimensional analogue of the Schwarzschild-anti-de Sitter space-time, and then the location of three-brane is determined by metric junction. The resulting Friedmann equation recovers standard cosmology, and a new term arises if the assumption $Z_2$-symmetry is dropped, which behaves as cosmological term in the early universe, next turns to negative curvature term, and finally damps rapidly.