Mean-field derivation of the interacting boson model Hamiltonian and exotic nuclei

This paper introduced firstly the density functional theory (DFT) as the microscopic mean-field theory of nucleon many-body system, and secondary the method for deriving the Hamiltonian of interacting boson model (IBM) as the phenomenological model of nuclear collective motions. This paper showed that this method is effective in the description of the energy and transition intensity of the excited state of quadrupole collective dynamics (vibration, rotation, and γ unstable nuclei) of medium-heavy nuclei, and proposed a unified methodology that can handle even the system of strong deformation. It further applied this methodology to more experimentally unknown unstable nuclei. As a result, it was able to contribute to the unstable nuclear research being made all over the world. As the derivation of IBM on the basis of mean field theory, it sowed for the first time that IBM is able to calculate the physical quantity of excited state difficult to calculate directly with DFT. Since the Hamiltonian of IBM is very versatile and simple, it has been applied to the prediction of a variety of nuclear structures. For example, there are the description of the structure of heavy atomic nucleus with octupole (pear shape) deformation and the description of the "deformation coexistence phenomena" where different deformation states co-exist in the vicinity of the ground state. On the other hand, it will become a future challenge to take up the cases when strong deformation occurs from spherical neighborhood, and to explicitly discuss the correlation between the elements of individual microscopic model and s/d bosons, as was made by Otsuka-Arima-Iachello method. (A.O.)