  In the lattice work by Miller [1,2] and in the work by Zwanziger [3] a linear
growth of the trace anomaly for high temperatures was found in pure SU(2) and
SU(3) Yang-Mills theories. These results show the remarkable property that the
corresponding systems are strong interacting even at high temperatures. We show
that within an analytical approach to Yang-Mills thermodynamics this linear
rise is obtained and is directly connected to the presence of a
temperature-dependent ground state, which describes (part of) the
nonperturbative nature of the Yang-Mills system. Our predictions are in
approximate agreement with [1,2,3]
