Background: The electric giant-dipole resonance (GDR) is the most established collective vibrational mode of excitation. A charge-exchange analog, however, has been poorly studied in comparison with the spin (magnetic) dipole resonance (SDR). Purpose: I investigate the role of deformation on the charge-exchange dipole excitations and explore the generic features as an isovector mode of excitation. Methods: The nuclear energy-density functional method is employed for calculating the response functions based on the Skyrme--Kohn--Sham--Bogoliubov method and the proton-neuton quasiparticle-random-phase approximation. Results: The deformation splitting into $K=0$ and $K=\pm 1$ components occurs in the charge-changing channels and is proportional to the magnitude of deformation as is well known for the GDR. For the SDR, however, a simple assertion based on geometry of a nucleus cannot be applied for explaining the vibrational frequencies of each $K$-component. A qualitative argument on the strength distributions for each component is given based on the non-energy-weighted sum rules taking nuclear deformation into account. The concentration of the electric dipole strengths in low energy and below the giant resonance is found in neutron-rich unstable nuclei. Conclusions: The deformation splitting occurs generically for the charge-exchange dipole excitions as in the neutral channel. The analog pygmy dipole resonance can emerge in deformed neutron-rich nuclei as well as in spherical systems.

中文翻译：

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变形核中的电荷交换偶极子激发

背景：电巨偶极共振（GDR）是最成熟的集体振动激发模式。然而，与自旋（磁）偶极共振 (SDR) 相比，电荷交换类似物的研究很少。目的：我研究变形对电荷交换偶极子激发的作用，并探索作为等向量激发模式的一般特征。方法：基于Skyrme--Kohn--Sham--Bogoliubov方法和质子-中子准粒子-随机相位近似，采用核能-密度泛函法计算响应函数。结果：变形分裂为 $K=0$ 和 $K=\pm 1$ 分量发生在电荷变化通道中，并且与 GDR 众所周知的变形量成正比。然而，对于特别提款权，不能应用基于原子核几何的简单断言来解释每个 $K$ 分量的振动频率。基于将核变形考虑在内的非能量加权求和规则，给出了关于每个组件的强度分布的定性论证。在富含中子的不稳定核中发现了低能量和低于巨共振的电偶极强度集中。结论：变形分裂一般发生在电荷交换偶极子激发中，就像在中性通道中一样。模拟侏儒偶极子共振可以出现在变形的富中子核以及球形系统中。基于将核变形考虑在内的非能量加权求和规则，给出了关于每个组件的强度分布的定性论证。在富含中子的不稳定核中发现了低能量和低于巨共振的电偶极强度集中。结论：变形分裂一般发生在电荷交换偶极子激发中，就像在中性通道中一样。模拟侏儒偶极子共振可以出现在变形的富中子核以及球形系统中。基于将核变形考虑在内的非能量加权求和规则，给出了关于每个组件的强度分布的定性论证。在富含中子的不稳定核中发现了低能量和低于巨共振的电偶极强度集中。结论：变形分裂一般发生在电荷交换偶极子激发中，就像在中性通道中一样。模拟侏儒偶极子共振可以出现在变形的富中子核以及球形系统中。变形分裂一般发生在电荷交换偶极子激发中，如在中性通道中。模拟侏儒偶极子共振可以出现在变形的富中子核以及球形系统中。变形分裂一般发生在电荷交换偶极子激发中，如在中性通道中。模拟侏儒偶极子共振可以出现在变形的富中子核以及球形系统中。