A model is presented which describes any hadronic form factor with one, two, or three particles off shell. The model is based on the salient most successful features of the dual and Regge models, and its unitarization can be achieved in a straightforward manner. Some of the effects of taking the nucleons off shell in the $\pi \mathrm{NN}$ vertex are discussed. Finally, it is argued that this form factor together with a $\pi +2\mathrm{}\pi +\omega$ dispersion-theoretical nucleon-nucleon model can explain the long standing puzzle of the triplet $D$-wave phase shifts.

NUCLEAR REACTIONS Baryon boson form factor, nucleon nucleon scattering, 0-400 MeV $\mathrm{NN}$ phase shifts.

• Received 23 April 1979

DOI:https://doi.org/10.1103/PhysRevC.22.160