A new unified model of dark matter and dark energy in 5-dimensional $f(R,\phi)$ gravity

TL;DR

This paper introduces a five-dimensional $f(R,\,\phi)$ gravity model with a scalar field that unifies dark matter and dark energy, linking bulk and brane cosmologies and deriving matter density ratios.

Contribution

It presents a novel 5D $f(R,\,\phi)$ gravity framework that unifies dark matter and dark energy through a scalar field in the bulk, connecting higher-dimensional gravity to observable cosmology.

Findings

Dark matter represented by scalar field mass

Dark energy as scalar field kinetic energy

Predicted matter density ratios consistent with observations

Abstract

We propose a new unified model that describes~dark energy and dark matter in the context of $f(R,\phi )$ gravity using a massive scalar field in five dimensions. The scalar field is considered in the bulk that surrounds the 3-brane in branworld model. We show that for a specific choice of the $% f(R,\phi )$ function, we can describe the Einstein gravitation in 4-dimensional space-time. We obtain a relationship between the speed of the universe's expansion and the speed of the bulk's expansion. We also propose that the dark matter is represented by the scalar field mass and that the dark energy is a kinetic energy of this field. Finally, we show that, according to conditions, one can obtain the percentages of density\ of dark matter and the density of ordinary matter.