  When thermal QCD crosses the critical temperature from below, its pressure
density rises drastically, consistent with the picture of deconfinement and the
release of partons as light degrees of freedom. On the other hand, the concept
of partons is a perturbative one, whereas interactions with the infrared modes
in the plasma always introduce non-perturbative contributions. Here I show how
partonic correlators can be defined in a gauge invariant and non-perturbative
manner which applies to all energy scales. In particular, I compute the
magnetic mass for hot SU(2) gauge theory and find $m_A=0.36(2)g^2T$, whose
inverse for large $T$ is the largest correlation length in the system.
