Giant Monopole Resonance and Nuclear Incompressibility of Hypernuclei

The isoscalar giant monopole resonances (ISGMRs) of hypernuclei 42 λλCa, 122 λλ Sn, and 210 λλ Pb are investigated using a fully self-consistent SkyrmeHartreeFock plus random phase approximation method. The Skyrme-type forces, SGII, No.5 and Sλλ1, are adopted to describe the nucleonnucleon, λ hyperonnucleon and λ hyperon-λ hyperon (λλ) interactions, respectively. For a given hyperon fraction, we find that effects of λλ 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 λ 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 λ hyperons. The constrained energies are increased by about 0.50.7MeV, which consequently enhances the effective incompressibility modulus of hypernuclei.