$\eta$-${\eta }^{\prime }$ Mixing in Large-$N_c$ Chiral Perturbation Theory

P. Bickert, P. Masjuan, S. Scherer

We present a calculation of the $\eta$-${\eta }^{\prime }$ mixing in the framework of large-$N_c$ chiral perturbation theory. A general expression for the $\eta$-${\eta }^{\prime }$ mixing at next-to-next-to-leading…