MA, BQ (reprint author), CHINA CTR ADV SCI & TECHNOL,CTR THEORET PHYS,WORLD LAB,BEIJING,PEOPLES R CHINA.
A relativistic two-level convolution model for deep-inelastic lepton nucleus scattering is presented in which the target nucleus is considered as a composite system of baryon-mesons which are also composite systems of quark-gluons, with each level based on the light-cone quantum field theory, respectively. In this prescription the impulse approximation is justified, the baryon number conservation is naturally guaranteed, and the off-shell ambiguity in the nucleonic approach is fixed. The scaling variable for bound nucleons is derived in a realistic way from the constraint of overall "energy" conservation, and a two-level convolution formula for nuclear-structure functions is given. It is shown that the European Muon Collaboration effect seems unable to be explained by the off-shell effect in terms of nucleonic degrees of freedom alone in this prescription.