Collective nuclear states as symmetric couplings of proton and neutron excitations

Collective nuclear states are described by symmetric couplings of proton and neutron pairs. These J=0 and J=2 pairs are represented by s- and d-bosons respectively. The multiplet structure of the combined system is given by representations of the SU (6) × SU (2) group, the Arima-Iachello interacting bosons corresponding to the fully symmetric ones. The validity of the boson picture is attributed to the attractive proton-neutron interaction which is also responsible for the transition from vibrational to rotational spectra