Modification of triaxial deformation and change of spectrum in $^{25}_{\ \Lambda}$Mg caused by $\Lambda$ hyperon

TL;DR

This study investigates how adding a $\Lambda$ hyperon to $^{25}$Mg affects its energy spectrum and deformation, revealing specific shifts and deformation reductions in certain nuclear bands.

Contribution

It provides the first detailed analysis of the impact of a $\Lambda$ hyperon on the deformation and energy spectrum of $^{25}_{\Lambda}$Mg using antisymmetrized molecular dynamics.

Findings

The $K^^+ \u2297 $ band energy shifts upward by about 200 keV.

The $$ hyperon reduces quadrupole deformation in the $K^^+ \u2297 $ band.

Deformation of the $K^^+ \u2297 $ band remains largely unchanged.

Abstract

The positive-parity states of $^{25}_{\ \Lambda}$Mg with a $\Lambda$ hyperon in $s$ orbit were studied with the antisymmetrized molecular dynamics for hypernuclei. We discuss two bands of $^{25}_{\ \Lambda}$Mg corresponding to the $K^\pi=0^+$ and $2^+$ bands of $^{24}$Mg. It is found that the energy of the $K^\pi = 2^+ \otimes \Lambda_s$ band is shifted up by about 200 keV compared to $^{24}$Mg. This is because the $\Lambda$ hyperon in $s$ orbit reduces the quadrupole deformation of the $K^\pi = 0^+ \otimes \Lambda_s$ band, while it does not change the deformation of the $K^\pi = 2^+ \otimes \Lambda_s$ band significantly.