Phantom Mimicry on the Normal Branch of a DGP-inspired Braneworld Scenario with Curvature Effect

TL;DR

This paper explores how phantom-like cosmic acceleration can occur on the normal branch of a DGP-inspired braneworld model with curvature effects, without violating energy conditions, by incorporating a Gauss-Bonnet term and a scalar field.

Contribution

It extends the DGP-inspired $f(R,\,\phi)$ model to include Gauss-Bonnet curvature effects, analyzing phantom behavior and crossing of the phantom divide in a unified scalar-curvature framework.

Findings

Phantom-like behavior achieved without phantom matter.

Gauss-Bonnet term modifies the cosmological dynamics.

Possible crossing of the phantom divide line.

Abstract

It has been shown recently that phantom-like effect can be realized on the normal branch of the DGP setup without introduction of any phantom matter neither in the bulk nor on the brane and therefore without violation of the null energy condition. It has been shown also that inclusion of the Gauss-Bonnet term in the bulk action modifies this picture via curvature effects. Here, based on the Lue-Starkman conjecture on the dynamical screening of the brane cosmological constant in the DGP setup, we extend this proposal to a general DGP-inspired $f(R,\phi)$ model that stringy effects in the ultra-violet sector of the theory are taken into account by inclusion of the Gauss-Bonnet term in the bulk action. We study cosmological dynamics of this setup, especially its phantom-like behavior and possible crossing of the phantom divide line especially with a non-minimally coupled quintessence field on the brane. In this setup, scalar field and curvature quintessence are treated in a unified framework.