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

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