We study the Gamow-Teller (GT) and the M1 spin transitions of the s — d shell nuclei $^{24}$Mg, $^{26}$Mg, $^{28}$Si, $^{32}$S, and $^{36}$Ar by using a quasiparticle random phase approximation (QRPA) scheme that comprises neutron-proton (np), neutron-neutron (nn) and proton-proton (pp) QRPA owing to the inclusion of the np pairing, as well as nn and pp pairing correlations. At present, we work in spherical symmetry under the assumption that the deformations of the nuclei considered in this work are small enough to neglect, as was customary in past applications. For the GT transition, as well as single and double beta decays, the neutron-proton QRPA (np QRPA) is usually employed. For the M1 spin transition, the pp and nn QRPA is needed due to its neutral current property. The np pairing correlations couple the np QRPA to the nn and pp QRPA. Therefore, the coupled np + nn + pp QRPA enables us to investigate simultaneously the GT and the M1 spin transitions. In particular, in this work, detailed analyses of particle-particle and particle-hole interactions at the QRPA stage are performed for the GT and the M1 spin transitions of the well-known s — d shell N ≃ Z nuclei, and the results are compared to available data. The roles of the np pairing correlations are also discussed for those transitions.

中文翻译：

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Gamow-Teller 的中子-质子、中子-中子、质子-质子 QRPA 和 s — d 壳中 N ≃ Z 核的 M1 自旋跃迁

我们研究了 Gamow-Teller (GT) 和 s — d 壳核的 M1 自旋跃迁 $^{24}$Mg, $^{26}$Mg, $^{28}$Si, $^{32} $S 和 $^{36}$Ar 通过使用包含中子-质子 (np)、中子-中子 (nn) 和质子-质子 (pp) QRPA 的准粒子随机相位近似 (QRPA) 方案，因为包含np 配对，以及 nn 和 pp 配对相关性。目前，我们假设在这项工作中考虑的原子核的变形小到可以忽略，就像过去应用中的习惯一样，我们在球对称下工作。对于 GT 跃迁以及单和双 β 衰变，通常采用中子-质子 QRPA (np QRPA)。对于 M1 自旋跃迁，由于其中性电流特性，需要 pp 和 nn QRPA。np 配对相关性将 np QRPA 耦合到 nn 和 pp QRPA。因此，耦合的 np + nn + pp QRPA 使我们能够同时研究 GT 和 M1 自旋跃迁。特别是，在这项工作中，对众所周知的 s — d 壳 N ≃ Z 核的 GT 和 M1 自旋跃迁在 QRPA 阶段进行了粒子 - 粒子和粒子 - 空穴相互作用的详细分析，结果是与现有数据相比。还讨论了这些转换的 np 配对相关性的作用。