Low-lying 2+ states in neutron-rich oxygen isotopes in quasiparticle random phase approximation

The properties of the low-lying, collective 21+ states in neutron-rich oxygen isotopes are investigated in the framework of self-consistent microscopic models with effective Skyrme interactions. In RPA the excitation energies E2+1 can be well described but the transition probabilities are much too small as compared to experiment. Pairing correlations are then accounted for by performing quasiparticle RPA calculations. This improves considerably the predictions of B(E2) values and it enables one to calculate more reliably the ratios Mn/Mp of neutron-to-proton transition amplitudes. A satisfactory agreement with the existing experimental values of Mn/Mp is obtained.