Expanding Cosmologies in Brane Geometries

TL;DR

This paper explores five-dimensional gravity with scalar fields in brane geometries, revealing models with time-dependent scales and warp factors, but without accelerated expansion, contributing to cosmological brane-world theories.

Contribution

It introduces a new class of brane cosmologies with dynamic scale factors and effective parameters, extending previous models with novel time-dependent features.

Findings

Recovered known models in specific limits

Identified a temporally expanding four-dimensional geometry

Found the expansion is not accelerated

Abstract

Five dimensional gravity coupled, both in the bulk and on a brane, to a scalar Liouville field yields a geometry confined to a strip around the brane and with time dependent scale factors for the four geometry. In various limits known models can be recovered as well as a temporally expanding four geometry with a warp factor falling exponentially away from the brane. The effective theory on the brane has a time dependent Planck mass and ``cosmological constant''. Although the scale factor expands, the expansion is not an acceleration.