The spatial string tension, a classic non-perturbative probe for the
convergence of the weak-coupling expansion at high temperatures, can be
determined in full QCD as well as in a dimensionally reduced effective theory.
Comparing both approaches, we find surprisingly good agreement almost down to
the critical temperature of the deconfinement phase transition.Comment: 6 pages, 2 figures, talk given at Lattice 2005 (nonzero temperature
and density
