[en] In order to clarify whether the liquid-gas phase transition is relevant to the multi-fragment formation found in intermediate energy heavy-ion collisions, we estimate the densities and temperatures at fragment formation in Au+Au collisions at incident energies of 150 MeV/A and 400 MeV/A within the Quantum Molecular Dynamics (QMD) model with and without quantum fluctuations implemented according to the Quantal Langevin (QL) model. The calculated results show that the IMFs are mainly produced inside the unstable region of nuclear matter, which supports the idea of the fragment formation from supercooled nuclear matter. (author)

[en] The pseudo-critical temperature of the confinement–deconfinement transition and the phase transition surface are investigated by using the complex chemical potential. We can interpret the imaginary chemical potential as the Aharonov–Bohm phase, then the analogy of the topological order suggests that the Roberge–Weiss endpoint would define the pseudo-critical temperature. The behavior of the Roberge–Weiss endpoint at small real quark chemical potential is investigated with the perturbative expansion. The expected QCD phase diagram at complex chemical potential is presented.

[en] Properties of hadronic matter produced in the region far away from the standard nuclear matter density by the high energy nuclear reactions are reviewed. At first an overview of the phase diagram of the hadronic matter is introduced. In the low temperature and low density nuclear matter, the first order gas-liquid phase transition is observed in the calorimetric curve of heavy ion collisions. When the baryon density is increased keeping the temperature low, as in the neutron stars, the Fermi energy and nucleon interaction increase to result in creation of various hadrons. Among them, particles containing strangeness quark play important roles. The equation of state greatly depends on the hyperon potential at various densities. Lagrangean is formulated based on the relativistic mean field theory considering the flavor SU(3) symmetry. Recent experimental studies to measure hyperon potential in nuclear matter and hypernuclear physics are described taking the KEK experiment of (π^-, K⁺) reaction as an example. In high temperature and/or high density matter, the greatest objective at present is to observe the quark gluon plasma (QGP) in which state quarks and gluons are released from confinement. Recent progress of theoretical predictions of the QGP phase is described. Two QGP signals observed at RHIC experiments are taken up. The first one is the jet quenching in the high momentum region which is the disappearance of the parton jet because of the parton energy loss in QGP that could be observed otherwise. The second one is the collective flow in the low momentum region. The large collective flow estimated from the experiment cannot be reproduced by the hadron model without secondary scattering by QGP. Finally the intermediate momentum region is discussed and 'recombination and fragmentation' model is presented. (S. Funahashi)

[en] The physics of the QCD phase diagram is discussed in view from heavy-ion collisions, compact astrophysical phenomena, lattice QCD and chiral effective models. We find that (T, μ_B) region probed in heavy-ion collisions and the black hole formation processes covers most of the critical point locations predicted in recent lattice QCD Monte-Carlo simulations and chiral effective models of QCD. We also discuss the consistency of the statistical model results and dynamical model description. (author)

No abstract available

[en] We analyze the invariant mass spectrum of Λ-Λ in ¹²C(K^-, K⁺ΛΛ) reaction at P_K^- = 1.65 GeV/c by using a combined framework of IntraNuclear Cascade (INC) model and the correlation function technique. The observed enhancement at low-invariant masses can be well reproduced with attractive Λ-Λ interactions with the scattering length either in the range a = -6 ∼ -4 fm (no bound state) or a = 7 ∼ 12 fm (with bound state). We also discuss Λ-Λ correlation functions in central relativistic heavy-ion collisions as a possible way to eliminate this discrete ambiguity

[en] We formulate a method for incorporating quantum fluctuations into molecular-dynamics simulations of many-body systems, such as those employed for energetic nuclear collision processes. Based on Fermi's Golden Rule, we allow spontaneous transitions to occur between the wave packets which are not energy eigenstates. The ensuing diffusive evolution in the space of the wave packet parameters exhibits appealing physical properties, including relaxation towards quantum-statistical equilibrium. (author)

[en] We have applied a microscopic simulation method called Antisymmetrized Molecular Dynamics (AMD) to calculations of the total reaction cross section. The effects of the Pauli blocking and internuclear potential on the total reaction cross section are analyzed in this method. The reactions X+¹²C, X=d, ³He, ⁴He, over an energy range from 10MeV/A to 1GeV/A are analyzed and the calculated results show good agreement with experimental data. It is shown that each of these effects, which are ignored in the usual Glauber type calculation, amounts to about 20% at low energy regions. A large cancellation between these effects can be seen in the reaction with d and ³He induced reactions, however, in the case of α-induced reaction, the effects of the Pauli-blocking is much larger than those of nuclear potential. We have also applied this method to the reactions induced by unstable nuclei ⁶He. (author)

[en] In order to investigate the effects of the Pauli blocking and internuclear potential on the total reaction cross section, we apply a microscopic simulation method called Antisymmetrized Molecular Dynamics to the optical limit of the Glauber model. We have analyzed reactions induced by d, ³He, α and ⁶He projectiles on ¹²C target over an energy range from 10 MeV/A to 1 GeV/A, are the calculated results show good agreement with experimental data. It is shown that each of these effects, which are ignored in the usual Glauber-type calculation, amounts to about 20% at low energy regions, however, large cancellations occur when we include both effects. (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)