Bethe-Salpeter equation for elastic nucleon-nucleon scattering

The Bethe-Salpeter equation for $\mathrm{NN}$ scattering with one-boson exchange is investigated for the case in which the pion-nucleon coupling is described by axial-vector theory. In contrast to the results with pseudoscalar coupling, good agreement with the experimental data can be obtained for all partial waves. Also, the deviations from the Blankenbecler-Sugar equation are not as large as they are for pseudoscalar coupling. In addition, cancellations between the direct and the crossed box graph with pseudoscalar $\pi N$ coupling are investigated for the ${}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}$ phase shift in the framework of the variational operator Padé approximation.