Mixed-symmetry interpretation of some low-lying bands in deformed nuclei

An alternative interpretation of the second excited $K^{\pi }$ ${=0\mathrm{}}^{+}$ band in rare earth nuclei, as a mixed-symmetry state in the neutron-proton interacting boson model, is compared with the conventional interpretation as a two-quasiparticle band. It is shown that, on the basis of electromagnetic decay probabilities and particle transfer amplitudes alone, it is difficult to discriminate between the two interpretations. Only on the level of form factors and transition densities do major differences occur.