The role of constituent quark exchange on the NLO structure function and the EMC ratios of the ⁴He nucleus

Abstract.

As in our recent work for the ⁶Li nucleus, we intend to reformulate the valence quark exchange formalism (VQEF) for the ${A}=4$ iso-scalar system and apply it to extract the u -d constituent quark distribution functions of the ⁴He nucleus. The constituent quark model (CQM) is used to evaluate the point-like parton distribution functions (PDF), the structure functions (SF), and the EMC ratio of this light nucleus, at the leading order (LO) and the next-to-leading-order (NLO) levels. Subsequently, the results are compared with our previous corresponding works and available experimental data. It is shown that the present framework provides the desirable results. It can be asserted that the common simplified VQEF, in which quark exchanges are considered between only two nucleons, plus the CQM, i.e. the constituents of the quark exchange model (CQEM), may be a reliable approximation to elicit the proper parton distributions of the light nuclei. However this argument should be tested at least for a few $A\le 16$ nuclei. Finally, as we pointed out in our prior report for the ⁶Li nucleus, it can also be concluded that the LO approximation may be enough to calculate the EMC ratio of the bound nuclei.