Generalized parton distributions and tit nucleon spin structute

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The main purpose of the present project is to clarify the spin structure of the nucleon through the study of the generalized parton distributions (GPDs) functions based on the chiral quark soliton model. To evaluate GPDs, which depend on 3 kinematical variables, with full account of the nonperturbative polarization of the Dirac sea quarks is extremely difficult. As a first step, we therefore tried to evaluate the forward limit of the GPDs H and E, and also the corresponding generalized form factors, which are functions of 4-momentum transfer, defined as the x-moments of H and E. Although these quantities express only one profile of GPDs depending on 3 variables, they are shown to play crucial roles in disentangling the spin contents of the nucleon. In the process of this analyses, we noticed that we can make almost model-independent predictions on the nucleon spin contents and their scale dependence, solely relying upon the empirical information, and showed that the role of nucleon constituents as carriers of the nucleon spin are remarkably different below and above 1 GeV scale. To undertand this transition around 1GeV scale is extremely important for connecting the nonperturbative physics at low energy scale and the perturbative physics at high energy scale. Our predictions on the scale dependence of the nucleon spin contents will eventually be tested through precise measurements of GPDs. In parallel with this main research, we also carried out a comparative theoretical analysis of the transversities and the longitudinally polarized distribution functions and also performed a theoretical analysis of the NuTeV anomaly concerning the deviation of the Weinberg angle from the standard theory. We have also succedeed to give an analytical proof for the existence of delta-function type singularity in the chiral-odd twist-3 parton distribution e (x), and could connect its origin to nontrivial structure of the QCD vacuum.