On the Boson-Fermion Interaction

Abstract

Since it has become increasingly evident that the IBA model and its extension to odd-A nuclei provides at the level of phenomenology an extremely successful description of nuclear collective phenomena, a microscopic understanding of the model is clearly of considerable interest. For the case of even-even nuclei Arima et al.¹ have proposed a method to derive the main properties of the boson-boson interaction from a shell model picture. Application of this method by Otsuka² to realistic cases has been shown to give promising results. In the present contribution the boson-fermion³ interaction, that enters in the description of odd-A nuclei, is derived from the shell model interaction between fermions. The latter has two main characteristics: i) a strong pairing force between the like nucleons, and ii) a quadrupole-quadrupole interaction between neutrons and protons. In terms of boson-boson interactions the former gives rise to attractive binding energies of the s- and d-bosons, whereas the latter leads to the quadrupole-quadrupole force between the neutron and proton bosons. It will be shown in this contribution that this interaction also plays a dominant role in the coupling of the odd-fermion to the bosons in the core⁴.