Impurity effect of $\Lambda$ hyperon on shape-coexistence nucleus $^{44}$S in the energy functional based collective Hamiltonian

TL;DR

This study uses a Skyrme energy density functional-based collective Hamiltonian to analyze how a $ ext{Lambda}$ hyperon influences the shape coexistence and collective properties of the nucleus $^{44}$S, finding a small reduction effect.

Contribution

It introduces a quantitative analysis of the impurity effect of $ ext{Lambda}$ hyperon on $^{44}$S using a non-relativistic EDF-based collective Hamiltonian with various Skyrme forces.

Findings

Small (~5%) reduction in collective properties due to $ ext{Lambda}$ hyperon.

Consistent results across different Skyrme forces and pairing strengths.

The impurity effect is generally small regardless of interaction parameters.

Abstract

The non-relativistic Skyrme energy density functional (EDF) based collective Hamiltonian, that takes into account dynamical correlations related to the restoration of broken symmetries and fluctuations of quadrupole collective variables, is applied to quantitatively study the impurity effect of $\Lambda$ hyperon on the collectivity of $^{44}$S. Several Skyrme forces for both the nucleon-nucleon ($NN$) and $\Lambda$-nucleon ($\Lambda N$) interactions are used. The influence of pairing strengths on the polarization effect of $\Lambda$ hyperon is also examined. It is found that although these Skyrme forces with different pairing strengths give somewhat different low-lying spectra for $^{44}$S, all of them give similar and generally small size of $\Lambda$ reduction effect (within 5%) on the collective properties.