INCLUSION OF PI-NN VERTEX INTO DELTA-ISOBAR DYNAMICS

A force model is discussed for the description of the two-nucleon system below and above pion threshold and its coupled inelastic channels with one pion. It uses DELTA-isobar and pion degrees of freedom in addition to the nucleonic ones. It is constructed to be valid up to 500 MeV centre-of-mass energy. The characteristic of the force model is its mechanism for pion production and pion absorption which is mediated simultaneously by the DELTA-isobar and through the pion-nucleon-nucleon vertex. The physical nucleon becomes a composite system consisting of a bare nucleon and of pion-nucleon configurations. The required scattering theory for coupled two- and three-particle systems is presented. The force model is applied to elastic and inelastic two-nucleon scattering in isospin triplet and isospin singlet partial waves.