The F-spin symmetric limits of the neutron-proton interacting boson model

Abstract The F -spin symmetric limits U (5), SU (3), and O (6) of the neutron-proton interacting boson model are studied. The conditions for and consequences of F -spin symmetry are investigated. In each of the three limits closed expressions for the following properties are given: the excitation energies; the M 1, E 2, and M 3 excitation strengths from the ground state to all 1 + , 2 + , and 3 + states; the M 1 and E 2 decay of the nonsymmetric 1 + and 2 + states; and the dipole and quadrupole moments of maximal F -spin states and of the nonsymmetric 1 + and 2 + states. The predictions for these properties are compared with the experimental data.