Study of high energy nuclear reactions based on quantum chromodynamics

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High energy nuclear reaction has two aspects, one related to perturbative QCD through elementary processes at large momentum transfers and the other related to non- perturbative QCD through the internal structure of participating hadrons and their initial and final state interactions. In this research project, the Nambu Jona- Lasino model has been studied as a relativistic model of the nucleon internal structure. The nuclear transparency which is a measure of initial and final state interactions and the H-dibaryon in nuclear matter have been also studied as means of observing the internal structure in high energy reactions.In the study of the NJL model, we have calculated the quark scalar density, the axial vector coupling constant and the magnetic moment of the nucleon in order to examine the properties of the solution for th relativistic Faddeev equation and confirmed that the observed properties of the nucleon are globally reproduced. We have also made a comparison between the three … More -quark picture based on the Faddeev approach and the soliton picture based on the mean field approach. It has been found that the inclusion of the two-body correlation in the mean field approach may solve the long-standing problem about the stability of the solution and the pion exchange between the quarks gives an important contribution in the Faddeev approach.As for the nuclear transparency, the relativistic effect has been found to suppress the expansion rate of the proton squeezed by the large momentum transfer and play an essential role in the color transparency. A relativistic harmonic oscillator quark model has been used to study the above suppression. The extension of the study to the cases of hadronic quasi-elastic processes such as (p, 2p) and (pi, pi'p) are under way.H-dibaryon in nuclear matter has been studied by the Brueckner theory based on the H-nucleon interaction we obtained previously and the effective mass and the well depth have been calculated. The effects of H-LAMBDALAMBDA coupling have been also examined. Less