On the similarity of the parton distributions in nuclei with more than three nucleons

Abstract

It is shown that the latest results from NMC and E665 on the $F_2^A(x)/F_2^{D}(x)$ obtained in the shadowing region, bring new evidence of the universal $A$ -- dependence of distorsions of a free nucleon structure function by nuclear medium. The universality holds in the entire $x$ -range and can be explained as a saturation of the distortions of the parton distributions in a four-nucleon system.