The direct $\gamma$ decays of the giant dipole resonance (GDR) and the giant quadrupole resonance (GQR) of ${}^{208}\mathrm{Pb}$ to low-lying states are investigated by means of a microscopic self-consistent model. The model considers effects beyond the linear response approximation. The experimental $\gamma$-decay widths from GQR to the first $3^{-}$ state and the low-lying dipole states are well reproduced with the Skyrme interaction SkP. The strong sensitivity of $\gamma$ decay to the isospin of the involved states is proven. By comparing the decay widths between GDR to $2_1^{+}$ and GQR to $3_1^{-}$, a much larger weight of the $3_1^{-}$ component in the GQR wave function of ${}^{208}\mathrm{Pb}$ is deduced, with respect to the weight of the $2_1^{+}$ component in the GDR wave function. Thus, we have shown that $\gamma$ decay is a unique probe of the resonance wave functions, and a test ground for nuclear structure models.

中文翻译：

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从它们的γ衰变中了解巨共振的结构

直接 $\gamma$ 巨偶极共振（GDR）和巨四极共振（GQR）衰减 ${}^{208}铅$通过微观自洽模型研究低洼状态。该模型考虑了线性响应近似之外的影响。实验性的$\gamma$-从 GQR 到第一个的衰减宽度 $3^{-}$Skyrme 相互作用 SkP 很好地再现了状态和低位偶极子状态。强烈的敏感性$\gamma$证明了相关状态的同位旋衰减。通过比较 GDR 与$2_1^{+}$ 和 GQR 到 $3_1^{-}$, 更大的权重 $3_1^{-}$ GQR 波函数中的分量 ${}^{208}铅$ 推导出，相对于重量 $2_1^{+}$GDR 波函数中的分量。因此，我们已经证明$\gamma$ 衰变是共振波函数的独特探索，也是核结构模型的试验场。