Non-Adiabatic Meson Theory of Nuclear Forces

Two nucleon forces are studied using a technique with which a detailed account of the nucleon recoil during meson emission and absorption may be given. The nucleon motion is treated relativistically. The method is applied to the neutral scalar meson field. It is concluded that the conventional static approximation gives results for this case which are not misleading. It is pointed out that the concept of potential energy is not always applicable in such problems, its validity depending not so much on the "separation" of the nucleons as on the character of the wave function for the state of the system concerned.