Abstract
The usual approach to nucleon-nucleon dynamics is based on the potentials derived from the one-boson exchange approximation. Our aim is to investigate the dynamical content of simple. Lagrangians, depending at most on one free parameter, and where the pion is the only source of nuclear forces. Due to the pseudoscalar nature of the pion it is essential to use a fully relativistic formalism: indeed the nucleon negative-parity states, which are taken into account, appear to play a fundamental role especially at zero energy. The inadequacy of the Born series is over-come by applying to the Green's function an approximation (Pade approximation) derived from variational principles; this approximation enjoys unitarity, analyticity and bound-antibound-state poles. The results obtained for the standard Yukawa Lagrangian and the nonlinear σ-model. which fulfils the current algebra constraints, prove that the one- and two-pion forces are sulficient to reproduce quite well all the phase shifts up to 50 MeV, while from 50 MeV to 400 MeV some of the lowest waves still require further improvement. The inversion in theS-waves (the3P0 changes sign) is still lacking but the introduction of the ω-meson in the Lagrangian and inclusion of all possible couplings between physical and unphysical states (some of them were neglected) should provide it.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.