Dynamics of dark energy in a scalar-vector-torsion theory

TL;DR

This paper explores the cosmological behavior of dark energy within a scalar-vector-torsion framework, deriving equations, analyzing stability, and identifying solutions that explain the universe's accelerated expansion.

Contribution

It introduces a novel scalar-vector-torsion model with non-minimal coupling, revealing new scaling solutions and vector-dominated attractors for dark energy.

Findings

Reproduces the universe's thermal history

Finds new scalar-vector scaling solutions

Identifies vector-dominated attractor points

Abstract

We study the cosmological dynamics of dark energy in a scalar-vector-torsion theory. The vector field is described by the cosmic triad and the scalar field is of the quintessence type with non-minimal coupling to gravity. The coupling to gravity is introduced through the interaction between the scalar field and torsion, where torsion is defined in the context of teleparallel gravity. We derive the full set of field equations for the Friedmann-Lema\^{i}tre-Robertson-Walker space-time background and obtain the associated autonomous system. We obtain the critical points and their stability conditions, along with the cosmological properties of them. Thus, we show that the thermal history of the universe is successfully reproduced. Furthermore, new scaling solutions in which the scalar and vector field densities scale in the same way as the radiation and matter background fluids have been found. Finally, we also show that there exist new attractor fixed points whose nature is mainly vectorial, and which can explain the current accelerated expansion and therefore the dark energy-domination.