Influence of complex configurations on the properties of the pygmy dipole resonance in neutron-rich Ca isotopes

摘要

Starting from the quasiparticle random phase approximation based on the Skyrme interaction SLy5, we study the effects of phonon-phonon coupling (PPC) on the low-energy electric dipole response in ~(40-58)Ca. Using the same set of parameters we describe available experimental data for ~(40,44,48)Ca and give the prediction for ~(50-58)Ca. The inclusion of the PPC results in the formation of low-energy 1~- states. There is an impact of the PPC effect on low-energy E1 strength of ~(40,44,48)Ca. The PPC effect on the electric dipole polarizability is discussed. We predict a strong increase of the summed E1 strength below 10 MeV, with increasing neutron number from ~(48)Ca until ~(58)Ca.