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., He-3 and H-3. 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 mu(0)(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 He-3 and H-3 structure functions as those of neutrons and protons, respectively.