Using the Hartree-Fock plus random phase approximation (HF+RPA), we study the impurity effect of Λ hyperon on the collective vibrational excitations of double-Λ hypernuclei. To this end, we employ Skyrme-type ΛN and ΛΛ interactions for the HF calculations, and the residual interactions for the RPA are derived with the same interactions. We find that the inclusion of two Λ hyperons in 16O shifts the collective states toward higher energies. In particular, the energy of the giant monopole resonance of ΛΛ18O, as well as that of ΛΛ210Pb, becomes higher. This implies that the effective incompressibility modulus increases owing to the impurity effect of Λ particles, if the β-stability condition is not imposed.
ASJC Scopus subject areas
- Nuclear and High Energy Physics