Decay modes of the meson η′(958) and chiral-symmetry breaking

Abstract

Using the simple model that the amplitude for η′ → η π π is dominated by the δ (970) resonance we find a satisfactory fit to the data. The quadratic mass formula for η -η ′ mixing with a positive mixing angle (i.e. reduction of ss¯ content in the physical η state) is preferred in agreement with the requirement for η′ → 2γ . Failure of the current-algebra calculation for η′ → η π π is explained and is shown not to be evidence against the (3^∗ , 3) ⊕ (3 , 3^∗ ) model of chiral-symmetry breaking.