The NLO parton distribution in the (x, Q2)-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 F2p(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 A1p(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. (author)