Determination of the Pion-Nucleon Coupling Constant by means of the Nucleon-Nucleon Dispersion Relation

Making use of the dispersion relation for nucleon-nucleon scattering, the coupling constant between pion and nucleon is determined from the neutron-proton scattering length in triplet state and the binding energy of the deuteron. The coupling constant g2/4n: thus determined coincides with those deduced by other theories. ~ I. Introd 1lllction Attempts to determine the pion-nucleon coupling constant have been made by various authors. Otsuki and his colleagues1) were perhaps the first group that has succeeded to bring out this programme in a reliable way, and obtained y2/4 " = 0.065 "'-'0.090. However, their arguments, based mainly on the electric quadrupole moment of the deuteron, depends on the nature of nuclear forces at short distances, and could not avoid some arnbiguities in the course of calculations. * Concerning the pion-nucleon scattering and pion photo-production, calculations were made by Chew and Low2) by using their own formulation and by Bernardini3) et al. with the aid of the Kroll-Ruderman theorem. Recently, the dispersion relations for pion-nucleon scattering of Goldberger an