Implications on $\eta$-$\eta'$-glueball mixing from $B_{d/s} \to J/\Psi   \eta^{(')}$ Decays
  We point out that the recent Belle measurements of the $B_{d/s} \to J/\Psi \eta^{(')}$ decays imply large pseudoscalar glueball contents in the $\eta^{(\prime)}$ meson. These decays are studied in the perturbative QCD (PQCD) approach, considering the $\eta$-$\eta'$-$G$ mixing, where $G$ represents the pseudoscalar glueball. It is shown that the PQCD predictions for the $B_{d/s} \to J/\Psi \eta^{(')}$ branching ratios agree well with the data for the mixing angle $\phi_G\approx 30^\circ$ between the flavor-singlet state and the pure pseudoscalar glueball. Extending the formalism to the $\eta$-$\eta'$-$G$-$\eta_c$ tetramixing, the abnormally large observed $B_d\to K\eta'$ branching ratios are also explained. The proposed mixing formalism is applicable to other heavy meson decays into $\eta^{(\prime)}$ mesons, and could be tested by future LHCb and Super-$B$ factory data. 
Xin Liu, Hsiang-nan Li, and Zhen-Jun Xiao
hep-ph hep-ex