Nonperturbative Phenomena at High Temperature and Density

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Possible existence of color superconducting phase in Quantum Chromo Dynamics at high density has been pointed out by Iwasaki based on BCS-like mean field approach. An enhanced fluctuation of scaler density near chiral restoration has been reexamined by Hatsuda and Kuni-hiro. They have discussed that present experimental data imply such precursory phenomena. A new experiment has been proposed to confirm them. Driving mechanism of chiral symme-try breaking has been studied by Oka abd Takagi based on instanton induced interaction and Beth-Salpeter equation. Through the studies, chiral symmetric nature of , baryon spectrum has been clarified. A new method to evaluate effeciive potential has been developed by In-agaki. Structure of QCD vacuum has been analyzed by Suzuki and Miyamura using lattice simulation. It is found that both chiral symmetry breaking and topological structure are kept in a abelian projected gauge field occupied by monopoles. Internal structure of hadrons has been studied by Kodaira and Saito in perturbative and nonperturbative treatments. In the former, higher order correction has been newly calculated. Noda and Biyajima have analized high energy collisions of hadrons and leptons . Characteristics of baryon productions and multiparticle productions have been clarified. Kato and Tanaka has extended automatic cal-culation of Feynman diagram extended for the processes including super symmetric particles. Phase transition under high curvature has been investigated by Muta and Inagaki. Finally, a workshop has been organized in the end of the 1998 to discuss and to summerize results of this research program.