  We discuss anomalous fractional quantum Hall effect that exists without
external magnetic field. We propose that excitations in such systems may be
described effectively by non-interacting particles with the Hamiltonians
defined on the Brillouin zone with a branch cut. Hall conductivity of such a
system is expressed through the one-particle Green function. We demonstrate
that for the Hamiltonians of the proposed type this expression takes fractional
values times Klitzing constant. Possible relation of the proposed construction
with degeneracy of ground state is discussed as well.
