Possible Existence of a Heavy Neutral Meson

In an attempt to account for the charge distributions of the proton and the neutron as indicated by the electron scattering experiments,' we would like to consider the possibility that there may be a heavy neutral meson which can contribute to the form factor of the nucleon. We assume that this meson, p°, is a vector field with isotopic spin zero and a mass two to three times that of the ordinary pion, coupled strongly to the nucleon field. An isolated p° would decay through virtual nucleon pair formation according to the following schemes: