Production ofπ-Mesons in Nucleon-Nucleon Collisions

The production of $\pi$-mesons in nucleon-nucleon collisions as predicted by scalar meson theory, pseudoscalar meson theory with pseudoscalar and pseudovector coupling, and vector theory with vector coupling is compared with the experimental results of the workers at Berkeley. The calculations are made on the basis of third-order perturbation theory using the methods of Feynman and Dyson and also using a phenomenological treatment of the nucleon-nucleon interaction. Account is taken of the fact that the final nucleons are not in plane wave states. It is shown that pseudoscalar theory with pseudovector coupling gives qualitative agreement with experiment.