2-loop Quantum Yang-Mills Condensate as Dark Energy

TL;DR

This paper investigates a 2-loop quantum Yang-Mills condensate model as a dark energy candidate, demonstrating it naturally addresses the coincidence problem and aligns with recent observational data on the equation of state.

Contribution

It extends previous 1-loop models by analyzing 2-loop quantum corrections, showing stable tracking solutions and EoS crossing -1, providing a more robust dark energy model.

Findings

The model yields current dark energy and matter density parameters.

It features a stable attractor solution at late times.

The EoS crosses -1, matching recent observations.

Abstract

In seeking a model solving the coincidence problem, the effective Yang-Mills condensate (YMC) is an alternative candidate for dark energy. A study is made for the model up to the 2-loop order of quantum corrections. It is found that, like in the 1-loop model, for generic initial conditions during the radiation era, there is always a desired tracking solution, yielding the current status $\Omega_\Lambda \simeq 0.73$ and $\Omega_m \simeq 0.27$. As the time $t\to \infty$ the dynamics is a stable attractor. Thus the model naturally solves the coincidence problem of dark energy. Moreover, if YMC decays into matter, its equation of state (EoS) crosses -1 and takes $w\sim -1.1$, as indicated by the recent observations.