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

摘要

A next-to-leading order QCD analysis of polarized and unpolarized structure functions of the proton in the (x, Q 2)-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 F 2 p(x, Q 2) to the data. It is shown that our new NLO calculation improves our previous works. We argue that the valence quark scenario at some μ0 2 ≪ Q 2 is a reasonable assumption in the framework of the DGLAP evolution equation. In agreement with the data, it is demonstrated that the asymmetry A 1 p(x, Q 2) has no significant Q 2-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.