“…† Landau Institute of Theoretical Physics, Kosygin street 2, 117940 Moscow, Russia; e-mail: pgg@landau.ac.ru. ‡ CNRS (UMR 7641), Centre de Mathématiques Appliquées,École Polytechnique, 91128, Palaiseau, France; e-mail: novikov@cmap.polytechnique.fr k ∈ R 2 , k 2 = E > 0, where a priori unknown function f (k, l), k, l ∈ R 2 , k 2 = l 2 = E, arising in (2), is the classical scattering amplitude for (1). In addition, we consider the Faddeev eigenfunctions ψ for (1) (see [7], [13], [9]), specified by…”