[en] We discuss an often overlooked property of the interacting boson model in its simplest version. From a pure group theoretical treatment the IBM-1 has five instead of three dynamical symmetries. The origin and consequences of the two additional symmetries are presented. (author)

[en] The interacting boson model is first defined mathematically and then its two possible physical interpretations are discussed. The role of the neutron/proton degree of freedom is described. Brief mention is made of the extension to odd nuclei and finally an example of the mapping from a shell model calculation onto tne IBM is given

[en] A procedure for calculating the effective number of bosons in the Interacting Boson Model is proposed. As an example, a calculation is presented for the 50-82 major shell for protons in which there is a subshell closure at Z = 64. (orig.)

No abstract available

[en] The explicit expression of the seniority particle operator and its properties in the quasi-spin theory of nuclear physics is presented in this paper. The seniority particle operator can be used to construct D-pair in the microscopic theory of interacting boson model to avoid the seniority mixing problem.

[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] Probably not, but the authors present phenomenological evidence that the strength of this term necessary to reproduce collective M1-transition strength data could be significantly smaller than is conventionally assumed and therefore more in line with naive microscopic considerations. They also find that g-boson effects are important to the reproduction of the summed M1 strength

[en] This contribution reviews the symmetry properties of the interacting boson model of Arima and Iachello. While the concept of a dynamical symmetry is by now a familiar one, this is not necessarily so for the extended notions of partial dynamical symmetry and quasi dynamical symmetry, which can be beautifully illustrated in the context of the interacting boson model. The main conclusion of the analysis is that dynamical symmetries are scarce while their partial and quasi extensions are ubiquitous. (authors)

[en] The role of dynamic symmetries in physics is discussed, with particular emphasis to nuclear structure physics. The dynamic symmetries of the interacting boson model, with dynamic algebra U(6), are introduced and experimental examples are presented. Dynamic symmetries provide a classification scheme for even-even nuclei. Symmetries are further enlarged to supersymmetries, involving both fermionic and bosonic degrees of freedom. The dynamic supersymmetries of the interacting boson-fermion model, with dynamic superalgebra U(6/Ω), where Ω is the dimension of the fermionic space, are introduced and experimental examples presented. Supersymmetries provide a classification scheme for odd-even, even-odd and odd-odd nuclei

[en] Microscopic calculations of the parameters of the quadrupole operator of the Interacting Bose-Fermi Approximation are reported for the realistic case in which the valence orbits are nondegenerate. The results of these exact calculations are compared with those of an approximate formalism and in general reasonable agreement is found. (orig.)