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Chiral unitary approach to η' N scattering at low energies

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 experimental estimations of the η' N 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.