Microscopic investigation of IBM and IBFM

Abstract

A new approach to the microscopic investigation of the interacting boson model (IBM) and the interacting boson-fermion model (IBFM) is proposed. The S-pair degrees of freedom separated in the beginning are treated rigorously. The rest of the space is made up by a kind of quasi-fermions out of which the D-pairs are constructed. The odd nucleon is also a quasi-fermion. Both the S and D boson are constructed explicitly in the fermion space. They differ from the ideal bosons significantly and are used to define the quasi-boson model space. Some new features appear in the collective hamiltonian and transition operators so obtained: corresponding to the numerical coefficients in H, Q there appear operators and additional interaction terms appear in odd-A nuclei. Possible occurance of super-symmetry in nuclei is discussed. Good agreement is obtained in applying the formulation to the e-e nuclei 110Cd, 112∼114Sn and 148∼156Sm.