Theory of scattering of two quantum particles from a third heavy particle

We study the solution of Faddeev equation for the three-body problem in the limit when mass of one of the particles tends to infinity. It is shown that the solution does not have a continuous transition in this limit, and the required scattering amplitude for the two light particles from an infinitely heavy particle must be obtained by reconstructing the Faddeev equations, which reduces them to the equations of a two-body problem in a field.