QCD symmetries in η- and η′-mesic nuclei

Abstract

We discuss the role of QCD symmetries and confinement in understanding η- and η′-mesic nuclei. η and η′ bound states in nuclei are sensitive to the flavour-singlet component in the meson. The bigger the singlet component, the more attraction and the greater the binding. Recent results on the η′ mass in nuclei from the CBELSA/TAPS Collaboration are very similar to the prediction of the Quark Meson Coupling model. In the model, η–η′ mixing induces a factor of two enhancement of the η-nucleon scattering length aηN relative to the prediction with a pure octet η with real part about 0.8 fm.