Relation between shrinkage effect and compression of rotational spectrum in ${}_{\Lambda }^7$Li hypernucleus

Abstract

It has been shown experimentally that the ${}^6$Li nucleus shrinks by adding a $\Lambda$ particle while its spectrum is also compressed. We discuss the compatibility of these two effects, contrasting also with a relation between the shrinkage effect and the stability of the spectrum in the ${}_{\Lambda }^9$Be hypernucleus. To this end, we employ two-body $d$-${}_{\Lambda }^5$He and $\alpha$-${}_{\Lambda }^5$He cluster models for the ${}_{\Lambda }^7$Li and ${}_{\Lambda }^9$Be hypernuclei, respectively. We first argue that a Gaussian-like interaction between two clusters leads to a stabilization of the spectrum against an addition of a $\Lambda$ particle, even though the intercluster distance is reduced. In the case of ${}_{\Lambda }^7$Li, the spin-orbit interaction between the intercluster motion and the deuteron spin has to be considered also. We show that the shrinkage effect makes the expectation value of the spin-orbit potential larger, lowering the excitation energy for the ${}^6$Li($3^{+})\otimes \Lambda (1/2^{+})$ level.

8 pages, 8 eps figures

References in corpus (3)

• Deformation of Lambda hypernuclei
• Deformation of hypernuclei studied with antisymmetirzed molecular dynamics
• Shape of Lambda hypernuclei in (beta,gamma) deformation plane

Cited by in corpus (7)

• Microscopic particle-rotor model for low-lying spectrum of Lambda hypernuclei
• Electric dipole moment of the deuteron in the standard model with $NN-\Lambda N-\Sigma N$ coupling
• Collective excitations of $\Lambda$ hypernuclei
• Impurity effect of Lambda particle on the structure of 18F and 19F_Lambda
• Probable alpha and $14$^C cluster emission from hyper Ac nuclei
• Sum rule approach to a soft dipole mode in $\Lambda$ hypernuclei
• Reaction cross sections of hypernuclei and the shrinkage effect