[en] The interacting-boson--model parameters are examined from a shell-model viewpoint with use of the generalized seniority scheme in two nondegenerate j shells. Predictions for the interacting-boson--model parameters are obtained by constructing the boson image of the corresponding fermion operator and found to be in good overall agreement with the empirically determined values

[en] The phase transition from the superfluid to normal state with an increase of the seniority number in the two-level pairing force model is studied with a boson-fermion composite representation. Criteria for identifying the phase transition with observable phase characteristics are discussed

[en] We derive an approximate boson-quasifermion mapping of a single-j shell-model algebra, applicable to the seniority classification scheme, as an expansion in the ratio of the seniority quantum number to the level degeneracy, with selective summation of higher order terms. The procedure used is an extension of the algebraic technique first applied to the purely bosonic part of the mapping by Bonatsos, Klein, and Li. Only the maps of the generators are needed to derive a Hamiltonian for the interacting boson fermion model (IBFM), and these can be obtained in Hermitian form without having to go through the intermediary of a mapping of the fermion operators. Application of the results is illustrated by a fresh discussion of the so-called exchange interaction of the IBFM. A consistent mapping of the single fermion in terms of bosons and quasifermions is also derived that includes a consideration of the unusual properties of the quasifermions

[en] It is well known that for identical particles in a set of degenerate single particle orbits, the pairing interaction preserves generalized seniority. In this paper a generalized pairing interaction is discussed, which preserves some of the essential features of generalized seniority, even for non-degenerate orbits. The level scheme for two identical particles is discussed for several model configurations

[en] A non-spurious quasi-particle scheme is presented, its number-projection being exactly the broken-pair model. From this property, quantities needed in the broken-pair approach are easily evaluated by making use of the extreme simplicity of the quasi-particle algebra. Applications to the Hamiltonian operator and to one-body operators are presented for seniority v=0, 1 and 2

[en] The Nomura's identity N → - N for the widths of the eigen value spectra in scalar space of Boson and Fermion systems is shown to be valid for their quasispin subspaces also. It is shown that is alid even for their partial widths in quasispin subspaces. This result, besides paving a way to obtain the results for Boson systems from the known results for Fermion systems, gives us a way to obtain a class of SU(N) = O(N) Wigner coefficients from SU(N) = Sp(N) Wigner coefficients

[en] In search of a possible truncation scheme for shell model calculations, the yrast generalized seniority states are compared with the corresponding shell model states for the case of the Sn isotopes ^104-112Sn. For most of the cases the energies agree within a few hundred keV. For the 0⁺(2⁺) states the overlaps decrease from 97% (93%) in ¹⁰⁴Sn to 91% (78%) in ¹¹²Sn when the coefficients of the pairs in the S and D boson operators are allowed to vary with the number of particles. For constant pairing coefficients throughout the entire isotope range, the overlaps are considerably smaller. It is concluded, with the realistic effective interaction applied here, that a truncation scheme based on seniority zero and two states is inadequate when the number of valence particles gets large and that configurations of higher seniority should be included. copyright 1997 The American Physical Society

[en] Configuration-seniority spectral distributions are used to analyse some properties of Ni⁶², and the results compared with those of shell model. The goodness of the symplectic symmetry is discussed by investigating the distributions with fixed seniority in every orbit

No abstract available

[en] In the paper the mapping of fermion dynamical-symmetrical model (FDSM) on the Boson space is considered. By the Daison mapping method a generalized fermion operators of FDSM were obtained