Yang-Mills condensates in cosmology

TL;DR

This paper explores how SU(2) gauge fields, including pure Yang-Mills with a theta-term and Yang-Mills with Higgs, can drive inflation in homogeneous and isotropic cosmological models, offering new mechanisms for early universe expansion.

Contribution

It demonstrates that pure Yang-Mills theory with a theta-term can induce inflation, and identifies a unique gauge configuration that mimics an isotropic fluid in cosmology.

Findings

Pure Yang-Mills with a theta-term can produce inflation.

A specific gauge configuration mimics an isotropic fluid.

Yang-Mills with Higgs can also drive inflation in closed universes.

Abstract

We discuss homogeneous and isotropic cosmological models driven by SU(2) gauge fields in the framework of Einstein gravity. There exists a Yang-Mills field configuration, parametrized by a single scalar function, which consists of parallel electric and magnetic fields and has the stress tensor mimicking an homogeneous and isotropic fluid. The unique SU(2) gauge theory with spontaneous symmetry breaking sharing the same property is the Yang-Mills coupled to the complex doublet Higgs, this exists only in the case of the closed universe. This model contains an intrinsic mechanism for inflation due to the Higgs potential. Our second goal is to show that a successful inflation can be achieved also within the pure Yang-Mills theory adding an appropriate theta-term.