The Distribution of Constituent Charm Quarks in the Hadron
  Using a statistical approach in the framework of non-covariant perturbation theory the distributions for light and charmed quarks in the hadron have been derived, taking into account the mass of the charmed quark. The parameters of the model have been extracted from the comparison with NA3 data on hadroproduction of J/psi particles. A reanalysis of the EMC data on charm production in muon-nucleon scattering has been performed. It has been found in comparison with the conventional source of charmed quarks from photon-gluon fusion, that the EMC data indicate the presence of an additional contribution from deep-inelastic scattering on charmed quarks at large x. The resulting admixture of the Fock states, containing charmed quarks in the decomposition of the proton wave function is of the order of 1%. The approach presented for the excitation of the Fock states with charmed quarks can also be applied to states with beauty quarks as well as to the hadronic component of the virtual photon (resolved photon component). 
Yu. A. Golubkov