Instanton-induced charm contribution to polarized deep-inelastic scattering

Recent data on D decays involving $\eta'$ may be explained if the singlet axial current of charmed quarks has large matrix element to $\eta'$, and instantons were shown to be able to generate this effect. We study the magnitude of charm contributions to nucleon polarized structure functions generated in a similar way. Comparing the charm contribution, which is related to a dim(6) gluonic operator, to that of light quarks, which are related by the anomaly equation to $G\tilde G$, we found that the former has the same sign and is only 5-12 times smaller. Future experiments like COMPASS at CERN identifying charm production in DIS can measure this ``intrinsic polarized charm'' component of the nucleon.