[en] We study the properties of nuclear matter expanding dynamically using QMD model. For this purpose we developed an extended periodic boundary condition prescription. To calculate EOS of the expanding nuclear matter, the liquid-gas phase transition is discussed. (author)

[en] There are various approaches to nonequilibrium system. We use the projection operator method investigated by F. Shibata and N. Hashitsume on the linear sigma model at finite temperature and density. We derive a differential equation of the time evolution for the order parameter and pion number density in chiral phase transition. (author)

[en] The first symposium on Science of Hadrons under Extreme Conditions, organized by the Research Group for Hadron Science, Advanced Science Research Center, was held at Tokai Research Establishment of JAERI on March 11 and 12, 1999. The symposium was devoted for discussions and presentations of research results in wide variety of fields such as observation of X-ray pulsars, theoretical studies of nuclear matter, nuclear structure, low- and high-energy nuclear reactions and QCD. Thirty seven papers on these topics presented at the symposium are indexed individually. (J.P.N.)

[en] ¹S₀ pairing in nuclear matter is investigated by taking the hadron mass decrease into account via the 'In-Medium Bonn potential' which was recently proposed by Rapp et al. The resulting gap is significantly reduced in comparison with the one obtained with the original Bonn-B potential and we ascertain that the meson mass decrease is mainly responsible for this reduction. (author)

[en] In this work, we investigate the time evolution and the thermalization of the infinite system of hot hadron gas using URASiMA, which is based on the two body hadron-hadron collisions. Our results show that the system reaches the stationary state which almost conserves the detailed balance. The temperature of this system is defined by the slopes of Boltzmann distributions. The information about EOS will be studied in our future plan. (author)

[en] We propose a simple method to reproduce the ¹S₀ pairing properties of nuclear matter, which are obtained by a sophisticated model, by introducing a density-independent cutoff into the relativistic mean field model. This applies well to the physically relevant density range. (author)

[en] We analyze temporal and spatial meson correlators in quenched lattice QCD at T > 0. Above T_c we find different masses and (spatial) 'screening masses', signals of plasma formation, and indication of persisting 'mesonic' excitations. (author)

[en] We investigate Λ-Σ⁰ mixing through neutral pion condensation interior neutron matter, symmetric nuclear matter and hyperonic nuclear matter. Although there is no direct ΛΛπ coupling, the system gains energy as much as nucleon systems through Λ-Σ⁰ mixing. It is necessary to understand π condensation consistently with behavior of Σ in Λ hyper nuclei. (author)

[en] We propose a microscopic simulation for quark many-body system based on a molecular dynamics. Using confinement potential, one-gluon exchange potential and meson exchange potentials, we can construct color-singlet nucleons, nuclei and also an infinite nuclear/quark matter. Statistical feature and the dynamical change between confinement and deconfinement phases are studied with this molecular dynamics simulation. (author)

[en] We numerically solved fully (3+1)-dimensional relativistic hydrodynamical equation coupled with the baryon number conservation law without spatial symmetry. We discuss the effect of transverse expansion based on the deviation our numerical result from Bjorken's scaling solution. We analyze the space-time evolution of the QGP gas in the case of non cylindrical initial conditions. (author)