The pseudoscalar pion-nucleon interaction with the method of unitary Padé approximants of theS-matrix

• DOI: 10.1007/bf02758833
• Publication Date: 2008-01-19T04:53:01Z
• Authors: J. A. Mignaco; M. Pusterla; E. Remiddi
• Keywords: Formalism (music)

The formalism for the application of the Pade method to theS-matrix of the pion-nucleon scattering with the pseudoscalar field theory is introduced. The results of the pseudoscalar pion-nucleon theory due to the first nontrivial approximant and without any phenomenological parameter are in satisfectory agreement with the experimentalT=3/2 phase shifts (S31, P31, D35, D33 andP33, up to roughly 1500 MeV c.m. total energy), except for the width of theP33, which seems related with more involved dynamics than the one considered here. An interesting consistency between the γππ→ππ term in the present problem and the one predicted from the pure boson-boson interaction is achieved. The situation changes in the isospinT=1/2 where the mechanism of absorption with coupled channels and more inelastic contributions (by using approximants of higher order and matrices in two-body channel space) seem necessary to reproduce the strongly absorbed phase shifts.