Production of π -Mesons in Nucleon-Nucleon Collisions

The cross section for the production of π-mesons in nucleon-nucleon collisions is calculated at energies just above the threshold. The process is treated in complete analogy with photonic bremsstrahlung: the π-meson field is coupled to the nucleon and an empirical potential between the two nucleons ensures momentum and energy conservation. The nuclear potential is taken from the Berkeley experiments on neutron-proton scattering at 90 Mev. In this treatment the symmetric scalar theory yields zero cross section if the recoil of the nucleons is neglected. The symmetric pseudoscalar theory (with pseudovector coupling) leads to the results given in Tables I-III. The cross section obtained is several orders of magnitude smaller than the cross section obtained by Morette and Peng on the basis of a thoroughgoing field-theoretic approach.