Crossing the cosmological constant line in a dilatonic brane-world model with and without curvature corrections

TL;DR

This paper introduces a brane-world model with a dilatonic bulk and brane tension that can explain late-time cosmic acceleration and crossing of the phantom divide without phantom matter, highlighting the role of brane tension.

Contribution

It presents a novel brane-world framework that achieves late-time acceleration and phantom divide crossing through brane tension dynamics, independent of induced gravity effects.

Findings

Model reproduces late-time acceleration without phantom matter.

Crossing of the phantom divide occurs at maximum brane tension.

Results hold even without the induced gravity term.

Abstract

We construct a new brane-world model composed of a bulk -with a dilatonic field-, plus a brane -with brane tension coupled to the dilaton-, cold dark matter and an induced gravity term. It is possible to show that depending on the nature of the coupling between the brane tension and the dilaton this model can describe the late-time acceleration of the brane expansion (for the normal branch) as it moves within the bulk. The acceleration is produced together with a mimicry of the crossing of the cosmological constant line (w=-1) on the brane, although this crossing of the phantom divide is obtained without invoking any phantom matter neither on the brane nor in the bulk. The role of dark energy is played by the brane tension, which reaches a maximum positive value along the cosmological expansion of the brane. It is precisely at that maximum that the crossing of the phantom divide takes place. We also show that these results remain valid when the induced gravity term on the brane is switched off.