η→ π⁰ γγ decay in the three-flavor Nambu-Jona-Lasinio model

الأصل · EN

We study the η→ π⁰ γγ decay via the quark-box diagram in the three-flavor Nambu--Jona-Lasinio model that includes the Uₐ (1) breaking effect. We find that the η-meson mass, the η→ γγ decay width and the η→ π⁰ γγ decay width are in good agreement with the experimental values when the Uₐ (1) breaking is strong and the flavor SU(3) singlet-octet mixing angle θ is about zero. The photon energy and the photon invariant mass spectra in η→ π⁰ γγ are compared with those in the chiral perturbation theory.