Thermal ground state and nonthermal probes (Q277708)

Summary: The Euclidean formulation of \(\mathrm{SU}(2)\) Yang-Mills thermodynamics admits periodic, (anti)self-dual 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 \(\mathrm{SU}(2)_{\mathrm{CMB}}\), the Yang-Mills theory conjectured to underlie the fundamental description of thermal photon gases.