$\eta$-${\eta }^{\prime }$ mixing in large-$N_c$ chiral perturbation theory: discussion, phenomenology, and prospects

Patricia Bickert, Pere Masjuan, Stefan Scherer

A systematic study of the $\eta$-${\eta }^{\prime }$ mixing in Large-$N_c$ chiral perturbation theory is presented with special emphasis on the role of the next-to-next-to-leading-order contribution…