On the $η$ and f$_1$(1420) Couplings to the Nucleon

Abstract

We consider neutral pseudoscalar, $η$, and axial vector, $f_1(1420)$, mesons in the OZI-rule-respecting flavor basis, $\lbrace (\bar s s), {1\over \sqrt{2}}(\bar u u + \bar d d)\rbrace$, and suggest a scenario for their coupling to the nucleon. Within this framework, the non--strange parts of the $ηN$ and f$_1 N$ couplings are modeled by means of triangular $a_0πN$, and $K K^* (Λ/Σ)$ vertices, while the strange ones partly proceed via Goldberger-Treiman relations, which have been concluded solely on the grounds of current universality. The suggested model explains the observed suppression of the $ηN$ coupling with respect to the constituent quark model expectations, and predicts the coupling of $f_1$ to the nucleon.