Sum rule approach to a soft dipole mode in hypernuclei

Minato, Futoshi   ; Hagino, Koichi*

Applying the sum rule approach, we investigate the energy of a soft dipole motion in hypernuclei, which results from a dipole oscillation of a hyperon against the core nucleus in contrast to usual dipole motion induced by proton and neutron. To this end, we systematically study single- hypernuclei, from O to Pb, for which the ground state wave function is obtained in the framework of Hartree-Fock method with several Skyrme-type interactions. Our results indicate that the excitation energy of the soft dipole mode, decreases as the mass number increases. We find that the excitation energy is well parametrized as MeV as a function of mass number A.