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arXiv 2107.00867nucl-thnucl-ex
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轴对称Skyrme能量密度泛函方法中的等矢量巨共振和四极共振

Isovector giant monopole and quadrupole resonances in a Skyrme energy density functional approach with axial symmetry

Kenichi Yoshida

摘要:

[研究背景]巨共振(Giant Resonance,GR)是一种典型的集体振动模式。等矢量(IV)巨偶极共振的变形分裂是公认的。然而,与其他多极性的GR分裂还没有得到很好的理解。【目的】探索IV巨共振和IV巨共振四极激发,同时研究中性通道和电荷交换通道,试图获得变形核IV巨共振的一般特征。[方法]采用核能-密度泛函(EDF)方法:采用Skyrme-Kohn-Sham-Bogoliubov近似和准粒子无规相近似描述基态和向激发态的跃迁。【结果】发现了与核形变无关的同量异位素类似物或Gamow-Teller共振的能量区域内的超晶格强度的集中,以及由$2\hbar ω_0$激发的粒子-空穴组态组成的高能巨共振的出现。由于形变,在巨磁共振和四极共振中出现强度分布的分裂。四极共振的较低$K$态在扁长组态中能量较低且强度增强,在扁长组态中能量较低且强度增强,而对于$J=1$和$J=2$自旋四极共振,依赖于$K$的能量排序并不清楚. [结论]在巨共振和四极共振中,形变劈裂现象普遍存在。四极跃迁强度的$K$依赖性在很大程度上由密度分布的各向异性来理解。

英文摘要:

[Background] Giant resonance (GR) is a typical collective mode of vibration. The deformation splitting of the isovector (IV) giant dipole resonance is well established. However, the splitting of GRs with other multipolarities is not well understood. [Purpose] I explore the IV monopole and quadrupole excitations and attempt to obtain the generic features of IV giant resonances in deformed nuclei by investigating the neutral and charge-exchange channels simultaneously. [Method] I employ a nuclear energy-density functional (EDF) method: the Skyrme-Kohn-Sham-Bogoliubov and the quasiparticle random-phase approximation are used to describe the ground state and the transition to excited states. [Results] I find the concentration of the monopole strengths in the energy region of the isobaric analog or Gamow-Teller resonance irrespective of nuclear deformation, and the appearance of a high-energy giant resonance composed of the particle-hole configurations of $2\hbar ω_0$ excitation. Splitting of the distribution of the strength occurs in the giant monopole and quadrupole resonances due to deformation. The lower $K$ states of quadrupole resonances appear lower in energy and possess the enhanced strengths in the prolate configuration, and vice versa in the oblate configuration, while the energy ordering depending on $K$ is not clear for the $J=1$ and $J=2$ spin-quadrupole resonances. [Conclusions] The deformation splitting occurs generously in the giant monopole and quadrupole resonances. The $K$-dependence of the quadrupole transition strengths is largely understood by the anisotropy of density distribution.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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