  The long-range properties of the random flux model (lattice fermions hopping
under the influence of maximally random link disorder) are shown to be
described by a supersymmetric field theory of non-linear sigma model type,
where the group GL(n|n) is the global invariant manifold. An extension to
non-abelian generalizations of this model identifies connections to lattice
QCD, Dirac fermions in a random gauge potential, and stochastic non-Hermitian
operators.
