Feshbach-Villars formalism and pion-nucleon scattering

The Feshbach-Villars Hamiltonian formulation of the Klein-Gordon equation is used as the basis for a scattering theory for relativistic, spin-zero, particles. Time dependent and time independent scattering theories are developed. The time independent theory is used as the framework for a separable potential model for πN elastic scattering in P waves. This potential leads to a πN T matrix which has the right and left hand cuts associated with two-particle unitarity and crossing, respectively, as well as the direct and crossed nucleon poles with the proper residues. The effects of nucleon recoil are included. With a particular choice of the form factors in the potential, the Chew-Low T matrix is reproduced. NUCLEAR REACTIONS Relativistic scattering theory, pion-nucleon T matrix.