Dynamical dark energy from extra dimensions

TL;DR

This paper explores a multidimensional cosmological model with extra dimensions to explain the universe's late-time acceleration, but finds issues with internal space size and constant variation constraints.

Contribution

It introduces a specific higher-dimensional model with a M2-brane solution that accounts for cosmic acceleration and matches observational data.

Findings

Model predicts accelerating expansion of external space.

Internal space size is too large at present.

Variation of fine structure constant exceeds observational limits.

Abstract

We consider multidimensional cosmological model with a higher-dimensional product manifold M = R x R^{d_0} x H^{d_1}/\Gamma where R^{d_0} is d_0-dimensional Ricci-flat external (our) space and H^{d_1}/\Gamma is d_1-dimensional compact hyperbolic internal space. M2-brane solution for this model has the stage of accelerating expansion of the external space. We apply this model to explain the late time acceleration of our Universe. Recent observational data (the Hubble parameter at the present time and the redshift when the deceleration parameter changes its sign) fix fully all free parameters of the model. As a result, we find that considered model has too big size of the internal space at the present time and variation of the effective four-dimensional fine structure constant strongly exceeds the observational limits.