Dark Energy with a Triplet of Classical U(1) Fields

TL;DR

This paper introduces a novel dark energy model where a scalar field coupled to a triplet of classical U(1) gauge fields drives cosmic acceleration, predicts a suppressed gravitational wave background, and offers analytic insights into its behavior.

Contribution

It proposes a new mechanism for cosmic acceleration using gauge fields coupled to a scalar, avoiding fine-tuning and providing analytic results for dark energy properties.

Findings

Can induce brief cosmic acceleration without fine-tuning

Predicts suppression of long-wavelength gravitational waves

Provides analytic expressions for dark energy equation of state

Abstract

We present a new mechanism for cosmic acceleration consisting of a scalar field coupled to a triplet of classical U(1) gauge fields. The gauge fields are arranged in a homogeneous, isotropic configuration, with both electric- and magnetic-like vacuum expectation values. The gauge fields provide a mass-like term via a Chern-Simons interaction that suspends the scalar away from its potential minimum, thereby enabling potential-dominated evolution. We show this mechanism can drive a brief period of acceleration, such as dark energy, without the need for fine tunings. We obtain simple analytic results for the dark energy equation of state and dependence on model parameters. In this model, the presence of the gauge field generically leads to a suppression of long-wavelength gravitational waves, with implications for the experimental search for cosmic microwave background B-modes and direct detection of a stochastic gravitational wave background.