Gluon and charm content of theη′meson and instantons

Motivated by recent CLEO measurements of the $\overrightarrow{B}{\eta }^{\prime }K$ decay, we evaluate the gluon and charm content of the ${\eta }^{\prime }$ meson using the interacting instanton liquid model of the QCD vacuum. Our main result is $〈0|g^3{f}^{\mathrm{abc}}{G}_{\mu \nu }^a{G}_{\nu \alpha }^b{G}_{\alpha \mu }^c|{\eta }^{\prime }〉=-(2.3\mathrm{}–3.3)\hspace{0.5em}{\mathrm{GeV}}^2\times 〈0|g^2{G}_{\mu \nu }^a{G}_{\mu \nu }^a|{\eta }^{\prime }〉$. It is very large due to the strong field of small-size instantons. We show that it provides quantitative explanations of the CLEO data on the $\overrightarrow{B}{\eta }^{\prime }K$ decay rate (as well as the inclusive process $\overrightarrow{B}{\eta }^{\prime }+X)$, via a virtual Cabibbo-unsuppressed decay into a $\overline{c}c$ pair which then becomes ${\eta }^{\prime }$. If so, a significant charm component may be present in other hadrons also: We briefly discuss the contribution of the charmed quark to the polarized deep-inelastic scattering on a proton.