ON THE PION-PION RESONANCE IN THE p STATE

Quite recently there has been great interest in the question of the existence of a p resonance (isobar) in pion-pion scattering.¹ From a study of the structure of nucleons by the method of dispersion relations, Frazer and Fulco have concluded that an isobar with mass 435 Mev and halfwidth 10 Mev must exist in the p state of pion-pion systems.² Similar results on the presence of a p resonance in pion-pion scattering have also been obtained by other authors.³…