Topics in scattering theory

In part one it is shown, in a certain rather general sense of convergence, and with appropriate restrictions on the potential and expansion functions, that the Kohn variational principle converges to the correct answer in the case of two-particle S-wave scattering. In part two the two-particle Bethe-Salpeter equation is studied and a contour is given which makes the kernel for the equation describing the scattering of two baryons in the ladder approximation non-singular in the energy range between the first and second inelastic thresholds