Higher order scattering on asymptotically Euclidean Manifolds
  We develop a scattering theory for perturbations of powers of the Laplacian on asymptotically Euclidean manifolds. The (absolute) scattering matrix is shown to be a Fourier integral operator associated to the geodesic flow at time \pi on the boundary. Furthermore, it is shown that on \Real^n the asymptotics of certain short-range perturbations of \Delta^k can be recovered from the scattering matrix at a finite number of energies. 
T. J. Christiansen and M. S. Joshi