  We determine the |p|/m expansion of the two body scattering amplitude of the
quantum theory of a Chern-Simons field minimally coupled to a scalar field with
quartic self-interaction. It is shown that the existence of a critical value of
the self-interaction parameter for which the 2-particle amplitude reduces to
the Aharonov-Bohm one is restricted to the leading, nonrelativistic, order. The
subdominant terms correspond to relativistic corrections to the Aharonov-Bohm
scattering.
