STRUCTURE FUNCTIONS OF BOUND NUCLEONS - FROM THE EMC EFFECT TO NUCLEAR SHADOWING

We describe the nuclear structure functions in the whole range of the Bjorken variable x, by combining various effects in a many-step procedure. First, we present a QCD motivated model of nucleons, treated, in the limit of vanishing Q2, as bound states of three relativistic constituent quarks. Gluons and sea quarks are generated radiatively from the input valence quarks. All parton distributions are described in terms of the confinement (or nucleon's) radius. The results for free nucleons are in agreement with the experimental determinations. The structure functions of bound nucleons are calculated by assuming that the main effect of nucleon binding is stretching of nucleons. The larger size of bound nucleons lowers the valence momentum and enhances the radiatively generated glue and sea densities. In the small-x region the competitive mechanism of nuclear shadowing takes place. It also depends on the size of the nucleons. By combining stretching, shadowing and Fermi motion effects (the latter confined to very large x), the structure function ratio is well reproduced. Results are also presented for the A-dependence of the momentum integral of charged partons, the nuclear gluon distribution and the hadron-nuclei cross sections.