No abstract available

[en] A unified scheme for describing properties of nuclei is suggested. This scheme is based on the introduction of bosonic degrees of freedom and attempts to bring together the shell model, the collective model and the cluster model. (orig.)

[en] The structure of the boson expansion theory is explained based on simple models. The models demonstrate how this theory would work when applied to realistic cases

[en] The possibility of phase transitional behaviour in the Sm nuclei is discussed in relation to recent experiments on ¹⁵²Sm, in the context of both interacting boson model and geometric collective model calculations. (author)

[en] This important book presents an approach to understanding the atomic nucleus that exploits simple algebraic techniques. The book focuses primarily on a particular algebraic model, the Interacting Boson Model (IBM); it outlines the algebraic structure, or group theoretical basis, of the IBM and other algebraic models using simple examples. Both the comparison of the IBM with empirical data and its microscopic basis are explored, as are extensions to odd mass nuclei and to phenomena not originally encompassed within its purview. An important final chapter treats fermion algebraic approaches to nuclear structure which can be both more microscopic and more general, and which represent promising avenues for future research

[en] A method for obtaining classical mechanics from a quantum mechanical system is developed in this dissertation. This method is based on the time-dependent variational principle applied to a class of generalized coherent states. It is suggested that the relevant class of generalized coherent states for the low energy microscopic nuclear collective motion problem for even nuclei is composed of states of the form, exp(Σ/sub i/α/sub i/A/sub i/)0. The classical mechanics derived from this class of coherent states is used to study several models. The results from the most realistic of these models suggest that the interpretation of the s and d bosons in the interacting boson model as representing the motions of coherent pairs of nucleons coupled to angular momentum zero and angular momentum two is not adequate

[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] We present a method for evaluating plethysms of Schur functions that is conceptually simpler than existing methods. Moreover the algorithm can be easily implemented with an algebraic computer language. Plethysms of sums, differences and products of S-functions are dealt with in exactly the same manner as plethysms of simple S-functions. Sums and differences of S-functions are of importance for the description of multi-shell configurations in the shell model. The number of variables in which the S-functions are expressed can be specified in advance, significantly simplifying the calculations in typical applications to many-body problems. The method relies on an algorithm that we have developed for the product of monomial symmetric functions. We present a new way of calculating the Kostka numbers (using Gel'fand patterns) and give, as well, a new formula for the Littlewood-Richardson coefficients. (author)

[en] In a study parallel to one recently carried out for the interacting boson model, the behavior of the geometric collective model (GCM) with (partially restricted) random interactions is studied. In particular, we study the frequency distribution of E(4₁⁺)/E(2₁⁺) ratios. In addition, we characterize those GCM potentials giving E(5) spectra and distinguish them from others giving R_4/2∼2.3 but non-E(5) spectra

[en] We investigate the effect of the interplay between the interatomic interaction and impurity on dynamic localization for two interacting bosons held in driven one-dimensional lattices with an impurity. We find that the interplay of the interatomic interaction and impurity can induce second-order tunneling under the dynamic localization condition. In the resonant regime, where the impurity potential is equal to a multiple of the driving frequency, two bosons form a stable bound pair and the dominant tunneling of the doublon in the paired state is a second-order process. In the non-resonant regime, the tunneling dynamics of the single boson in the unpaired state can also be a second-order process between the two nearest-neighbor sites of the impurity with the negligible impurity site population, and the other boson is localized in the initial site all the time. Our results provide a promising approach for controlling transport of realistic systems. (paper)