  We consider the lattice regularization of a five dimensional SU(2) gauge
theory with periodic boundary conditions. We determine a consistent mean-field
background and perform computations of various observables originating from
fluctuations around this background. Our aim is to extract the properties of
the system in regimes of its phase diagram where it seems to be in a
dimensionally reduced state. Within the mean-field theory we establish the
existence of a second order phase transition at finite value of the gauge
coupling for anisotropy parameter less than one, where there is evidence for
dimensional reduction.
