An exactly solvable problem with energy dependent interaction is inves
tigated in the present paper. The selfadjoint model operator describes
the scattering problem for three one-dimensional particles. It is sho
wn that this problem is equivalent to the diffraction problem in the s
ector with energy dependent boundary conditions. The problem is solved
with the help of the Sommerfeld-Maluzhinetz representation, which tra
nsforms the partial differential equation for the eigenfunctions to a
functional equation on the integral densities. The solution of the fun
ctional equation can be constructed explicitly in the case of identica
l particles. The three-body scattering matrix describing rearrangement
and excitation processes is represented in terms of analytic function
s.