Application of random-phase approximation to vibrational excitations of double- hypernuclei

Minato, Futoshi   ; Hagino, Koichi*

Using the Hartree-Fock plus random-phase-approximation (HF+RPA), we study the impurity effect of hyperon on the collective vibrational excitations of double- hypernuclei. To this end, we employ a Skyrme-type and interactions for the HF calculations, and the residual interactions for RPA derived with the same interactions. We find that inclusion of two hyperons in O shifts the energy of the collective states towards higher energies. In particular, the energy of the giant monopole resonance of O, as well as that of Pb, becomes larger. This implies that the effective incompressibility modulus increases due to the impurity effect of particle, if the -stability condition is not imposed.