Gauge equivalence and inverse scattering for long-range magnetic   potentials
  For Schroedinger operators with long-range magnetic vector potentials and short-range electric scalar potentials in an exterior domain $\Omega$ in ${\bf R}^n$ with $n \geq 2$, we show that there is a one-to-one correspondence between the gauge equivalent classes of Hamiltonians and those of S-matrices if $\Omega$ is exterior to a bounded convex obstacle. 
Gregory Eskin and Hiroshi Isozaki
math-ph math.MP