ISACKER , Piet Van

We carry out a simple analysis of (n+3)-dimensional gravity in the context of recent work on 'large' supplementary dimensions and deduce a formula for the expected compactification radius for the n additional dimensions in the universe, as a function of the Planck and the electro-weak scales. We argue that the correspondingly modified...

Double−γ vibrations in deformed nuclei are analyzed in the context of the interacting boson model. A simple extension of the original version of the model towards higher-order interactions is required to explain the observed anharmonicities of nuclear vibrations. The influence of three- and four-body interactions on the moments of inertia of...

An intrinsic-state formalism for the interacting boson model IBM-4 is presented. A basis of deformed bosons is introduced which allows the construction of a general trial wave function that has Wigner's spin-isospin SU(4) symmetry as a particular limit. Intrinsic-state calculations are compared with exact ones, showing good agreement.

A Hartree-Bose mean-field approximation for the IBM-3 is presented. A Hartree-Bose transformation from the spherical to the deformed bosons with charge-dependent parameters is proposed which allows bosonic pair correlations and includes higher angular momentum bosons. The formalism contains previously proposed IBM-2 and IBM-3 intrinsic states...

Double-γ vibrations in deformed nuclei are studied in the context of the interacting boson model with special reference to their anharmonic character. It is shown that large anharmonicities can be obtained with interactions that are (at least) of three-body nature between the bosons. As an example the γ vibrations of the nucleus 16668Er98 are...

A Hartree-Bose mean-field approximation for the IBM-3 is presented. A Hartree-Bose transformation from spherical to deformed bosons with charge-dependent parameters is proposed which allows bosonic pair correlations and includes higher angular momentum bosons. The formalism contains previously proposed IBM-2 and IBM-3 intrinsic states as...

The effect of deformation on the excitation of multiple giant dipole resonances is studied. Analytical expressions are derived in the framework of the interacting boson model for the energies and E1 properties of giant dipole resonances in spherical and deformed nuclei, and a numerical treatment of transitional nuclei is proposed....

A general study of excitations up to two-phonon states is carried out using the intrinsicstate formalism of the Interacting Boson Model (IBM). Spectra and transitions for the different dynamical symmetries are analyzed and the correspondence with states in the laboratory frame is established. The influence of multi-phonon states is discussed....