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The large mass of the $\eta'$ meson indicates that a sizeable gluon componentis present in the meson wave function. However, the $\chi_{c0}$ and $\chi_{c2}$decays to $\eta'$ mesons, which proceed via a purely gluonic intermediate stateand we would therefore na\"{i}vely expect to be enhanced by such a component,are in fact relatively suppressed. We argue that this apparent contradictionmay be resolved by a proper treatment of interference effects in the decay. Inparticular, by accounting for the destructive interference between the quarkand gluon components of the $\eta'$ distribution function, in combination witha model for strange quark mass effects, we demonstrate that the observed$\chi_{c(0,2)}\to\eta(')\eta(')$ branching ratios can be reproduced for areasonable gluon component of the $\eta'$, $\eta$ mesons.

$\chi_c$ decays and the gluon content of the $\eta'$, $\eta$ mesons