  We propose a simple mean-field ansatz to study phase transitions from a
topological phase to a trivial phase. We probe the efficiency of this approach
by considering the string-net model in the presence of a string tension for any
anyon theory. Such a perturbation is known to be responsible for a
deconfinement-confinement phase transition which is well described by the
present variational setup. We argue that mean-field results become exact in the
limit of large total quantum dimension.
