Quintessence with Kaluza-Klein type couplings to matter and an isotropy-violating vector field

TL;DR

This paper explores a scalar field model with Kaluza-Klein couplings to dark matter and an anisotropic vector field, revealing exact solutions and conditions where anisotropy remains controlled, aligning closely with LCDM cosmology.

Contribution

It generalizes vector-coupled scalar field models to dark energy, providing exact anisotropic solutions and analyzing regimes with controllable anisotropy.

Findings

Existence of exact anisotropic power-law solutions.

Identification of a strong vector coupling regime with minimal anisotropy.

Solutions closely approximate the LCDM model.

Abstract

We study the dynamics of a scalar field with Kaluza-Klein type couplings to cold dark matter and an isotropy-violating vector field. The vector coupling, $f^2(\phi)F^2$, has been studied thoroughly in the context of inflation recently. We generalize the model to a dark energy context and study the cosmological consequences. We find a rich set of exact anisotropic power-law solutions and identify a strong vector coupling regime where the anisotropy is controllable and all solutions are close to the LCDM limit.