Particle-hole excitations in the interacting boson model (IV). The U(5)-SU(3) coupling Original Research Article

In the extended interacting boson model (EIBM) both particle- and hole-like bosons are incorporated to encompass multi-particle-multi-hole excitations at and near to closed shells. We apply the group theoretical concepts of the EIBM to the particular case of two coexisting systems in the same nucleus exhibiting a U(5) (for the regular configurations) and an SU(3) symmetry (for the intruder configurations). Besides the description of “global” symmetry aspects in terms of I-spin, also the very specific local mixing effects characteristic for the U(5)-SU(3) symmetry coupling are studi d. The model is applied to the Po isotopes and a comparison with a more realistic calculation is made.