Thermal ground state and nonthermal probes

TL;DR

This paper explores how (anti)calorons in SU(2) Yang-Mills thermodynamics influence the thermal ground state, leading to temperature-independent electromagnetic properties relevant to photon propagation.

Contribution

It demonstrates the association of (anti)calorons with electromagnetic constants in the thermal ground state of SU(2)$_{CMB}$, providing a novel link between topological solutions and photon properties.

Findings

(Anti)calorons generate temperature-independent permittivity and permeability.

The thermal ground state can be described by an inert adjoint scalar field.

Implications for photon propagation in the SU(2)$_{CMB}$ framework.

Abstract

The Euclidean formulation of SU(2) Yang-Mills thermodynamics admits periodic, (anti)selfdual solutions to the fundamental, classical equation of motion which possess one unit of topological charge: (anti)calorons. A spatial coarse graining over the central region in a pair of such localised field configurations with trivial holonomy generates an inert adjoint scalar field $\phi$, effectively describing the pure quantum part of the thermal ground state in the induced quantum field theory. Here we show for the limit of zero holonomy how (anti)calorons associate a temperature independent electric permittivity and magnetic permeability to the thermal ground state of SU(2)$_{\tiny\mbox{CMB}}$, the Yang-Mills theory conjectured to underlie photon propagation.