Boson Systems

Philip L. Taylor, Olle Heinonen

A. Kuriyama, Constança Providência, João da Providência +1 more

As preparation for extending a new boson realization in the Lipkin model, recently proposed by the present authors, a possible boson realization for a many-boson system is developed. The basic idea comes from the MYT boson mapping method. In order to obtain the classical counterpart to the quantal system in this new boson realization, a certain wave packet is used.

Cheng-Li Wu, D.H. Feng, Jin-Quan Chen +1 more

An effective boson Hamiltonian is derived from the original Hamiltonian of a many-fermion system. The results show that when the intrinsic motion of bosons is collective and the excitation energies of the system are small, the effective boson-boson interaction can be reduced to a two-body interaction while for odd systems or systems with uncorrelated fermions, there is an additional two-body boson-fermion interaction. Both these interactions can be calculated from the original fermion-fermion ones. Thus, the microscopic foundation of the interacting boson model is established without recourse to mapping procedures.NUCLEAR STRUCTURE Interacting boson model, boson fermion hybrid representation, microscopic foundation.

Xiao-Gang Wen

A. Kuriyama, João da Providência, Y. Tsue +1 more

With the aim of obtaining the classical counterpart of the su(2)-spin system and its quantal fluctuations in the frame of the boson coherent state, the Holstein-Primakoff and Marumori-Yamamura-Tokunaga boson expansions are investigated. The starting point is found in the Schwinger boson representation for the su(2)-spin system and its reformation. Dirac's canonical theory for constraint systems is also applied to the su(2)-spin system. In conclusion, the latter boson expansion is found to be superior to the former with respect to the use of the boson coherent state.