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Masahiro Isaka

Publications and source records attributed to Masahiro Isaka.

21 records · Page 2Linked to original sources

Superdeformed $Λ$ hypernuclei with antisymmetrized molecular dynamics

The response to the addition of a $Λ$ hyperon is investigated for the deformed states such as superdeformation in $^{41}_Λ$Ca, $^{46}_Λ$Sc and $^{48}_Λ$Sc. In the present study, we use the antisymmetrized molecular dynamics (AMD) model. It is pointed out that many kinds of deformed bands appear in $^{45}$Sc and $^{47}$Sc. Especially, it is found that there exists superdeformed states in $^{45}$Sc. By the addition of a $Λ$ particle to $^{40}$Ca, $^{45}$Sc and $^{47}$Sc, it is predicted, for the first time, that the superdeformed states exist in the hypernuclei $^{41}_Λ$Ca and $^{46}_Λ$Sc. The manifestation of the dependence of the $Λ$-separation energy on nuclear deformation such as spherical, normal deformation and superdeformation is shown in the energy spectra of $^{41}_Λ$Ca, $^{46}_Λ$Sc and $^{48}_Λ$Sc hypernuclei.

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

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

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Deformation of hypernuclei studied with antisymmetirzed molecular dynamics

An extended version of the antisymmetrized molecular dynamics to study structure of $p$-$sd$ shell hypernuclei is developed. By using an effective $ΛN$ interaction, we investigate energy curves of $^9_Λ$Be, $^{13}_Λ$C and $^{20,21}_Λ$Ne as function of nuclear quadrupole deformation. Change of nuclear deformation caused by $Λ$ particle is discussed. It is found that the $Λ$ in p-wave enhances nuclear deformation, while that in s-wave reduces it. This effect is most prominent in $^{13}_Λ$C. The possibility of the parity inversion in $^{20}_Λ$Ne is also examined.

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