Pion Prouction, Nuclear Dirac Phenomenology, and theπNNVertex

The amplitude for the ($p$,${\pi }^{+}$) reaction is calculated in a relativistic one-nucleon model with use of a distorted-wave Born-approximation approach. The nucleon continuum and bound-state wave functions are solutions of Dirac equations with appropriate vector and scalar nuclear potentials. Calculations with the pseudovector $\pi \mathrm{NN}$ coupling, which satisfies the constraints of partial conservation of axial-vector current, are in much better agreement with the data than calculations with the simple pseudoscalar coupling.