Chiral unitary approach to [formula omitted] scattering at low energies

Abstract

We study the η′N interaction within a chiral unitary approach which includes πN, ηN and related pseudoscalar meson–baryon coupled channels. Since the SU(3) singlet does not contribute to the standard interaction and the η′ is mostly a singlet, the resulting scattering amplitude is very small and inconsistent with the experimental scattering length. The additional consideration of vector meson–baryon states into the coupled channel scheme, via normal and anomalous couplings of pseudoscalar to vector mesons, enhances substantially the η′N amplitude. We also exploit the freedom of adding to the Lagrangian a new term, allowed by the symmetries of QCD, which couples baryons to the singlet meson of SU(3). Adjusting the unknown strength to the η′N scattering length, we obtain predictions for the elastic η′N→η′N and inelastic η′N→ηN, πN, KΛ, KΣ cross sections at low η′ energies, and discuss their significance.