On solving nonhomogeneous Bethe-Salpeter equations

A new method for solving nonhomogeneous Bethe-Salpeter equations is developed on the basis of employing expansions of interaction amplitudes and kernels in the basis of four-dimensional spherical harmonics. The method, which is applicable to both scalar and spinor equations, is expounded for the case of the nonhomogeneous Bethe-Salpeter equation for scalar particles in the ladder approximation. The model phase shifts calculated by this method are in good agreement with results published previously.