The $A$-dependence of the bond energy $\Delta B_{ \Lambda\Lambda}$ of the ${ \Lambda\Lambda}$ hypernuclear ground states is calculated in a three-body ${ \Lambda + \Lambda + { ^{ A}Z}}$ model and in the Skyrme-Hartree-Fock approach. Various ${ \Lambda\Lambda}$ and $\Lambda$-nucleus or ${ \Lambda N}$ potentials are used and the sensitivity of $\Delta B_{ \Lambda\Lambda}$ to the interactions is discussed. It is shown that in medium and heavy ${ \Lambda\Lambda}$ hypernuclei, $\Delta B_{ \Lambda\Lambda}$ is a linear function of $r_{ \Lambda}^{ -3}$, where $r_\Lambda$ is rms radius of the hyperon orbital. It looks unlikely that it will be possible to extract ${ \Lambda\Lambda}$ interaction from the double-$\Lambda$ hypernuclear energies only, the additional information about the $\Lambda$-core interaction, in particular, on $r_{ \Lambda}$ is needed.
Categories: nucl-th