Dynamic Pairing Effects on Low-Frequency Modes of Excitation in Deformed Mg Isotopes close to the Neutron Drip Line

Low-frequency quadrupole vibrations in deformed ${}^{36,38,40}$Mg are studied by means of the deformed Quasiparticle-RPA based on the coordinate-space Hartree-Fock-Bogoliubov formalism. Strongly collective $K^{\pi}=0^{+}$ and $2^{+}$ excitation modes (carrying 10-20 W.u.) are obtained at about 3 MeV. It is found that dynamical pairing effects play an essential role in generating these modes. It implies that the lowest $K^{\pi}=0^{+}$ excitation modes are particularly sensitive indicators of dynamical pairing correlations in deformed nuclei near the neutron drip line.