η-η' Mixing in η-Mesic Nuclei

η bound states in nuclei are sensitive to the flavour-singlet component in the η. The bigger the singlet component, the more attraction and the greater the binding. η-η' mixing plays an important role in understanding the value of the η-nucleon scattering length aηN. Working with the Quark Meson Coupling model, we find a factor of two enhancement from mixing relative to the prediction with a pure octet η. (authors)