Extended Lee model and three-particle equations

The extended Lee model describes the interaction of two fermions, V and N, with a scalar boson θ and its antiparticle θ̄ through the virtual processes VN+θ and NV+θ̄. Here it is shown that the amplitudes for the physical processes V+θ→V+θ and V+θ→N+2θ can be obtained in a reasonable approximation from the solution of an Amado-Lovelace type of three-particle equation. The analysis presented gives some insight into the problem of extending a crossing symmetric, Chew-Low type of T matrix off the energy shell. NUCLEAR REACTIONS Amado-Lovelace equations for V-θ sector of extended Lee model.