Giant Monopole Resonance and Nuclear Incompressibility of Hypernuclei

The isoscalar giant monopole resonances (ISGMRs) of hypernuclei ^42_\Lambda\LambdaCa, ^122_\Lambda\LambdaSn, and ^210_\Lambda\LambdaPb are investigated using a fully self-consistent Skyrme–Hartree–Fock plus random phase approximation method. The Skyrme-type forces, SGII, No.5 and S\Lambda\Lambda1, are adopted to describe the nucleon–nucleon, \Lambda hyperon–nucleon and \Lambda hyperon–\Lambda hyperon (\Lambda \Lambda) interactions, respectively. For a given hyperon fraction, we find that effects of \Lambda \Lambda interaction on the properties of infinite symmetric nuclear matter and finite hypernuclei are very small. The ISGMR strengths are shifted to the high energy region when two \Lambda are added into normal nuclei. The changes are from two parts, one is due to the mean field calculations, and the other is from the residual interaction associated with \Lambda hyperons. The constrained energies are increased by about 0.5–0.7 MeV, which consequently enhances the effective incompressibility modulus of hypernuclei.