Brane-world solutions, standard cosmology, and dark radiation

TL;DR

This paper presents new exact solutions in brane-world cosmology showing how a parameter called dark radiation influences the universe's evolution, deviating from standard cosmology predictions.

Contribution

It introduces a family of exact solutions with an arbitrary constant affecting cosmological evolution, highlighting the role of dark radiation in brane-world models.

Findings

Dark radiation modifies low-energy brane-world cosmology.

Standard cosmology is recovered when the dark radiation constant is zero.

Non-zero dark radiation leads to observable deviations in cosmological evolution.

Abstract

New exact solutions of brane-world cosmology are given. These solutions include an arbitrary constant C, which is determined by the geometry outside the brane and which affects the cosmological evolution in the brane-world. If C is zero, then the standard cosmology governs the brane-world as a low-energy effective cosmological theory. However, if C is not zero, then even in low-energy the brane-world cosmology gives predictions different from the standard one. The difference can be understood as ``dark radiation'', which is not real radiation but alters cosmological evolutions.