Cosmic acceleration in models with density dependent moduli

TL;DR

This paper explores models where the size of extra dimensions depends on local energy density, potentially leading to cosmic acceleration, by analyzing how such dependence affects the universe's expansion and the effective equation of state.

Contribution

It introduces a novel approach where density-dependent moduli influence cosmic acceleration, addressing the challenge of achieving acceleration through compact space dynamics.

Findings

Density-dependent moduli can induce cosmic acceleration.

The effective equation of state of matter is altered in these models.

Potential difficulties in finding suitable potentials are discussed.

Abstract

The effective equation of state of normal matter is changed in theories where the size of the compact space depends upon the local energy density. In particular we show how the dilution of a fluid due to the expansion of the universe can be compensated by an increase of the effective coupling of that fluid to gravity in the presence of a potential which acts to reduce the size of the compact space. We estimate how much cosmic acceleration can be obtained in such a model and comment on the difficulties faced in finding an appropriate potential.