Quantum Yang--Mills Dark Energy

TL;DR

This paper reviews how quantum non-Abelian gauge fields in an expanding universe can form condensates that drive cosmic acceleration and potentially explain dark energy through quantum effects and QCD vacuum dynamics.

Contribution

It provides a qualitative overview of quantum Yang--Mills fields in cosmology, highlighting their role in dark energy and the formation of gauge field condensates in an expanding universe.

Findings

Quantum effects influence cosmological evolution significantly.

Gauge field condensates may cause early and late-time acceleration.

Dark energy could arise from QCD vacuum contributions and quantum corrections.

Abstract

In this short review, I discuss basic qualitative characteristics of quantum non-Abelian gauge dynamics in the non-stationary background of the expanding Universe in the framework of the standard Einstein--Yang--Mills formulation. A brief outlook of existing studies of cosmological Yang--Mills fields and their properties will be given. Quantum effects have a profound impact on the gauge field-driven cosmological evolution. In particular, a dynamical formation of the spatially-homogeneous and isotropic gauge field condensate may be responsible for both early and late-time acceleration, as well as for dynamical compensation of non-perturbative quantum vacua contributions to the ground state of the Universe. The main properties of such a condensate in the effective QCD theory at the flat Friedmann--Lema\'itre--Robertson--Walker (FLRW) background will be discussed within and beyond perturbation theory. Finally, a phenomenologically consistent dark energy can be induced dynamically as a remnant of the QCD vacua compensation arising from leading-order graviton-mediated corrections to the QCD ground state.