Influence of mass parameters on the asymptotic behavior in the ladder model

Bethe–Salpeter equation for the scattering amplitude in the ladder approximation of the $\lambda\varphi^3$ theory with the exchange by massive particle is studied. Solutions of the equation for small and large values of the mass exchanged are obtained. It is shown that the introduction of the mass exchanged produces no noticeable effect in the scaling behaviour of the amplitude in the deep-inelastic region.