Octupole degrees of freedom in the Interacting Boson Model

We discuss the problem of describing collective states with negative parity by adding f bosons to the Interacting Boson Model. We consider both vibrational excitations, of which one f boson provides a good description, and octupole-deformed nuclei, a discussion of which requires many f bosons. We analyze dynamical symmetries associated with these cases and propose the introduction of a dipole p boson alongside the others to enrich the model's potential. We also analyze the classical large-N limit of our model in order to ascertain the connection between our negative-parity bosons and the liquid drop Hamiltonians currently being applied by others to the problem of octupole deformation. Finally, we examine the relevance of octupole bosons via an application to the structure of several Platinum and Radium isotopes, the latter of which are a source of long standing controversy