The results of the preceding paper are used to indicate procedures of calculation of the scattering amplitude, obtain several expansions, find bounds on the variation of the amplitude under a change in the potential, and study multiple scattering.
The Fredholm theory of integral equations is used to give a rigorous proof of the analyticity and boundedness of the ordinary nonrelativistic scattering amplitude for a fixed momentum transfer. The results follow from ordinary quantum mechanics and certain conditions on the potentials. These conditions are stated explicitly, and the bound states are treated with rigor. It is shown that the amplitude vanishes in the limit of large momenta, and thus simple dispersion relations are derived. Finally, it is proved that the partial-wave expansion is convergent in the unphysical region, provided the potentials satisfy the same conditions as above.
The self-adjoint extension (SAE) procedure is considered in the Schrodinger equation for potentials behaving as an attractive inverse square at the origin of coordinates. This approach guarantees self-adjointness of the radial Hamiltonian in three dimensions. It is shown that the single bound state appears after such an extension, which depends on SAE parameter. The same parameter arises for the scattering case as well, when the extension is made by orthogonality requirement. The closed form is derived for the modified scattering amplitude, which consists an extra factor depended on the SAE parameter. That guarantees the appearance of the same bound state in the form of the scattering amplitude pole. So, the generalization of pragmatic method is demonstrated in case of continuous spectrum.