The Structure Functions of 3 He and 3 H Nuclei in the Constituent Quark Exchange Model

The valence quark exchange (QE) model for the nuclear system and the constituent quark (CQ) model in which the quarks are assumed to be the complex objects, are used to calculate the parton distributions and the structure functions (SF) of ³ He and ³ H mirror nuclei. The effect and the role of sea quarks and gluons, and their contributions to the SF of ³ He and ³ H nuclei are analyzed. Specifically, for small x regions a more “realistic” result is found with respect to our previous works, in which only the valence quarks have been considered. By using the DGLAP evolution equations, the resulting parton distributions and SF are evolved to the high-energy scales and compared with available data. Finally, the ratios of ³ He to ³ H nuclei SF with the isospin symmetry assumption is compared to the results of the deep inelastic electron experiments on the ³ He and ³ H nuclei, especially, those which have been extracted from the kinematic region of the proposed 11 GeV upgraded beam experiment of Jefferson laboratory, and a reasonable agreement is found.     

The NLO Parton Distribution in the (x, Q 2)-Plane: A Relativistic Quark-Exchange Approach to A = 3 Mirror Nuclei

A next-to-leading order QCD analysis of polarized and unpolarized structure functions of the proton in the (x, Q²)-plane is discussed within the scheme of the radiation parton formalism. The valence quark distribution is obtained from the application of the relativistic quark-exchange model to A = 3 mirror nuclei, i.e., ³He and ³H. The sea quark and gluon distributions are calculated using the inverse Mellin technique in the NLO approximation. A comparison is made with the corresponding available experimental data. We find a good fit for F₂^p(x, Q²) to the data. It is shown that our new NLO calculation improves our previous works. We argue that the valence quark scenario at some μ₀² ≪ Q² is a reasonable assumption in the framework of the DGLAP evolution equation. In agreement with the data, it is demonstrated that the asymmetry A₁^p(x, Q²) has no significant Q²-dependence as we go to the small x, even at NLO limit. Finally we argue that for small x ≤ 0.2 it is a good approximation to consider ³He and ³H structure functions as those of neutrons and protons, respectively.