Parton distributions and EMC ratios of the 6Li nucleus in the constituent quark exchange model

Abstract

While the constituent quark model (CQM), in which the quarks are assumed to be the complex objects, is used to calculate the parton distribution functions of the iso-scalar lithium-6 (6Li) nucleus, the u–d constituent quark distribution functions of the 6Li nucleus are evaluated from the valence quark exchange formalism (VQEF) for the A=6 iso-scalar system. After computing the valence quark, sea quark, and gluon distribution functions in the constituent quark exchange model (CQEM, i.e., CQM+VQEF), the nucleus structure function is calculated for the 6Li nucleus at the leading order (LO) and the next-to-leading-order (NLO) levels to extract the European muon collaboration (EMC) ratio, at different hard scales, using the standard Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGALP) evolution equations. The outcomes are compared with those of our previous works and the available NMC experimental data, and various physical points are discussed. It is observed that the present EMC ratios are considerably improved compared with those of our previous works, in which only the valence quark distributions were considered to calculate the EMC ratio, and are closer to the NMC data. Finally, it is concluded that at a given appropriate hard scale, the LO approximation may be enough for calculating the nucleus EMC ratio.