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We study instanton contributions to hadronic decays of the scalar glueball,the pseudoscalar charmonium state $\eta_c$, and the scalar charmonium state$\chi_c$. Hadronic decays of the $\eta_c$ are of particular interest. The threemain decay channels are $K\bar{K}\pi$, $\eta\pi\pi$ and $\eta'\pi\pi$, eachwith an unusually large branching ratio $\sim 5%$. On the quark level, allthree decays correspond to an instanton type vertex$(\bar{c}c)(\bar{s}s)(\bar{d}d)(\bar{u}u)$. We show that the total decay rateinto three pseudoscalar mesons can be reproduced using an instanton sizedistribution consistent with phenomenology and lattice results. Instantonscorrectly reproduce the ratio $B(\pi\pi\eta)/B(\pi\pi\eta')$ but over-predictthe ratio $B(K\bar{K}\pi)/B(\pi\pi\eta(\eta'))$. We consider the role of scalarresonances and suggest that the decay mechanism can be studied by measuring theangular distribution of decay products.Comment: 29 pages, added reference

Instanton contribution to scalar charmonium and glueball decays