  We investigate the scattering of a quantum particle with a two-dimensional
(2D) Rashba spin-orbit coupled dispersion off of circularly symmetric
potentials. As the energy of the particle approaches the bottom of the lowest
spin-split band, i.e., the van Hove singularity, earlier work has shown that
scattering off of an infinite circular barrier exhibits a number of features
unusual from the point of view of conventional 2D scattering theory: the
low-energy S-matrix is independent of the range of the potential, all partial
waves contribute equally, the differential cross section becomes increasingly
anisotropic and 1D-like, and the total cross section exhibits quantized
plateaus. Via a nonperturbative determination of the T-matrix and an optical
theorem which we prove here, we show that this behavior is universal for Rashba
scattering off of any circularly symmetric, spin independent, finite-range
potential. This is relevant both for impurity scattering in the noninteracting
limit as well as for short-range two-particle scattering in the interacting
problem.
