Speaker
Description
The $\Lambda\Lambda$ bond energies ($\Delta B_{\Lambda\Lambda}$) of double-$\Lambda$ hypernuclei provide a measure of the nature of the in-medium strength of the $\Lambda\Lambda$ interaction. Likewise, the charge symmetry breaking in mirror nuclei with $\Lambda$ and $\Lambda\Lambda$ is expected to shed light on $\Lambda$N and $\Lambda\Lambda$N interactions. The $\Lambda\Lambda$-separation energy ($B_{\Lambda\Lambda}$) from a double-$\Lambda$ nucleus exceeds twice the value of the $\Lambda$-separation energy ($B_{\Lambda}$) of a single-$\Lambda$ nucleus and this excess is known as the bond energy given by,
$\Delta B_{\Lambda\Lambda}$=$B_{\Lambda\Lambda}$ ($^A_{\Lambda\Lambda}$Z)- 2$B_{\Lambda}$ ($^{A-1}_{\Lambda}$Z),
where A is the mass number with the hyperon number included. A generalized mass formula, constructed earlier with broken SU3 symmetry, is employed to calculate the separation energies from light to heavy nuclei. The newly available experimental data on $\Lambda\Lambda$ -separation energy of several double-$\Lambda$ nuclei, and some single-$\Lambda$ nuclei put stringent constraint on this formula leading to a modification of one of its parameters. The $B_{\Lambda}$ , $B_{\Lambda\Lambda}$ and $\Delta B_{\Lambda\Lambda}$ values calculated with this revised mass formula are in good agreement with the experimental data. Results are also compared with the recent predictions from the quark mean-field model (QMF) and the relativistic mean-field (RMF) approach. The mass formula enables prediction of the bond energy and symmetry energy for a wide range of nuclei for which experimental $\Lambda$- and $\Lambda\Lambda$-separation energy values are not yet available. Both the bond energies and the charge symmetry breaking in mirror nuclei are found to have definite A-dependence.
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