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arXiv 2108.08702nucl-th
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基于点耦合相对论Hartree Bogoliubov模型的温度线性响应理论

Finite-temperature linear response theory based on relativistic Hartree Bogoliubov model with point-coupling interaction

A. Ravlić, Y. F. Niu, T. Nikšić, N. Paar, P. Ring

摘要:

基于有限温度相对论Hartree-Bogoliubov(FT-RHB)模型,在电荷交换通道中发展了有限温度线性响应理论,研究了自旋-同位旋激发的温度演化.计算进行自洽与相对论点耦合相互作用DD-PC 1和DD-PCX。在电荷交换通道中,配对相互作用可分为等载体($T = 1$)和等亲和力($T = 0$)部分。对于isovector分量,Gogny D1 S配对相互作用的相同的可分离形式被用于基态计算以及用于剩余相互作用,而在剩余相互作用中的isoscillation配对的强度通过与Gamow-Teller共振(GTR)和Isobaric analog resonance(IAR)的偶偶锡同位素的质心能量差的实验数据进行比较来确定。通过在巨正则系综中处理Bogoliubov准粒子引入了温度效应。因此,不同于传统的配方的准粒子随机相位近似(QRPA)的基础上的Bardeen-Cooper-Schrieffer(BCS)的基础上,我们的模型制定的Hartree-Fock-Bogoliubov(HFB)准粒子基础。实现一个相对论性的点耦合相互作用和一个可分离的配对力允许减少复杂的两体剩余相互作用矩阵元素,这大大降低了问题的坐标空间中的维度。这种方法的主要优点是避免了大的QRPA矩阵的对角化,特别是在有限温度下,配置空间的大小显着增加。线性响应代码的实现被用来研究温度范围内$T = 0 - 1.5$ MeV的偶-偶锡同位素的IAR,GTR和自旋偶极共振(SDR)的温度演化。

英文摘要:

The finite-temperature linear response theory based on the finite-temperature relativistic Hartree-Bogoliubov (FT-RHB) model is developed in the charge-exchange channel to study the temperature evolution of spin-isospin excitations. Calculations are performed self-consistently with relativistic point-coupling interactions DD-PC1 and DD-PCX. In the charge-exchange channel, the pairing interaction can be split into isovector ($T = 1$) and isoscalar ($T = 0$) parts. For the isovector component, the same separable form of the Gogny D1S pairing interaction is used both for the ground-state calculation as well as for the residual interaction, while the strength of the isoscalar pairing in the residual interaction is determined by comparison with experimental data on Gamow-Teller resonance (GTR) and Isobaric analog resonance (IAR) centroid energy differences in even-even tin isotopes. The temperature effects are introduced by treating Bogoliubov quasiparticles within a grand-canonical ensemble. Thus, unlike the conventional formulation of the quasiparticle random-phase approximation (QRPA) based on the Bardeen-Cooper-Schrieffer (BCS) basis, our model is formulated within the Hartree-Fock-Bogoliubov (HFB) quasiparticle basis. Implementing a relativistic point-coupling interaction and a separable pairing force allows for the reduction of complicated two-body residual interaction matrix elements, which considerably decreases the dimension of the problem in the coordinate space. The main advantage of this method is to avoid the diagonalization of a large QRPA matrix, especially at finite temperature where the size of configuration space is significantly increased. The implementation of the linear response code is used to study the temperature evolution of IAR, GTR, and spin-dipole resonance (SDR) in even-even tin isotopes in the temperature range $T = 0 - 1.5$ MeV.

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