GLUON AND CHARM CONTENT OF THE ETA' MESON AND INSTANTONS

Motivated by recent CLEO measurements of the B-->eta'K decay, we evalu ate the gluon and charm content of the eta' meson using the interactin g instanton liquid model of the QCD vacuum. Our main result is [0\g(3) f(abc)G(mu nu)(a)(G) over tilde(nu alpha)(b)G(alpha mu)(c)\eta'] = -(2 .3-3.3) GeV2 X[0\g(2)G(mu nu)(a)(G) over tilde(mu nu)(a)\eta']. It is very large due to the strong field of small-size instantons. We show t hat it provides quantitative explanations of the CLEO data on the B--> eta'K decay rate (as well as the inclusive process B-->eta'+X), via a virtual Cabibbo-unsuppressed decay into a cc pair which then becomes e ta'. If so, a significant charm component may be present in other hadr ons also: We briefly discuss the contribution of the charmed quark to the polarized deep-inelastic scattering on a proton.