At very high temperatures Yang--Mills theories can be described through
perturbation theory. At the tree level the time components of the gluon fields
decouple and yield a dimensionally reduced theory. The expectation value of the
Polyakov loop then assumes values of the Z(N) center group. At intermediate
temperatures, however, this is not true anymore. The time dependence shows up
in loops. In a recent work we integrated out fast varying quantum fluctuations
around background A_i and static A_4 fields. We assumed that these fields are
slowly varying but that the amplitude of A_4 is arbitrary. As a result we
obtained the kinetic energy terms for the Polyakov loop both for the electric
and the magnetic sector of SU(2).Comment: 9 pages, 3 figures. Proceedings for Cracow School of Theoretical
Physics, Zakopane, May 30 - June 08, 200
