Distribution of Collective Magnetic Multipole Strength as a Measure of Neutron-Proton Symmetry Breaking

Abstract
The effect of neutron-proton symmetry breaking on the distribution of M1 and M3 strength in the SU(3) limit of the interacting-boson model (IBA-2) is studied. A possible alternative choice for the Majorana force is investigated, with a structure that resembles more closely that which is calculated in microscopic theories. It is found that the specific choice for the Majorana interaction has important consequences for the magnetic strength distribution function. This implies that a determination of this in deformed nuclei will impose strong constraints on the hitherto largely unknown Majorana force in the IBA-2 Hamiltonian.