Vector field as a quintessence partner

TL;DR

This paper explores how a vector field can influence the evolution of a flat, homogeneous, isotropic universe, offering an alternative to scalar quintessence with unique features like an induced mass that suppresses the cosmological constant.

Contribution

It derives generic equations for vector field-driven cosmology and provides exact solutions demonstrating inflation and dynamical cosmological constant behavior, highlighting differences from scalar field models.

Findings

Vector fields can drive inflationary expansion.

The vector field induces a mass proportional to the Hubble constant.

The model shows a dynamical suppression of the cosmological constant.

Abstract

We derive generic equations for a vector field driving the evolution of flat homogeneous isotropic universe and give a comparison with a scalar filed dynamics in the cosmology. Two exact solutions are shown as examples, which can serve to describe an inflation and a slow falling down of dynamical ``cosmological constant'' like it is given by the scalar quintessence. An attractive feature of vector field description is a generation of ``induced mass'' proportional to a Hubble constant, which results in a dynamical suppression of actual cosmological constant during the evolution.