Symmetrical Pseudoscalar Meson Theory Of Nuclear Forces

Nuclear forces yielded by the symmetrical pseudoscalar theory are discussed in terms of a perturbation expansion. It is shown that, up to terms in the square of the coupling constant, the pseudoscalar coupling is equivalent to a scalar pair coupling of the pseudoscalar field plus a pseudovector coupling of that field. The dominant contribution to the fourth-order nucleon potential is then obtained in a simple way by using this result.