arXiv 2601.145962026-01-21nucl-th

谱因子阈值效应如何影响重离子击出反应

How Threshold Effects in Spectroscopic Factors Influence Heavy-Ion Knockout Reactions

Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Southern Center for Nuclear-Science Theory (SCNT), Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所核科学理论南方中心）

M. R. Xie, J. G. Li, C. A. Bertulani, N. Michel, Y. Z. Sun, W. Zuo

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AI总结：

通过Gamow壳模型计算谱因子，解决重离子击出反应中谱因子阈值效应与费米面不对称性相关性的谜团。

摘要：

在重离子单核子击出反应中，一个存在二十年的谜团是减少因子R_s=σ_exp/σ_th与费米面不对称性ΔS之间的强相关性。理论截面通常依赖于壳模型（SM）计算的谱因子（SFs），这些计算忽略了连续耦合效应。在这里，我们采用Gamow壳模型（GSM），该模型明确地纳入了连续耦合效应，来计算p壳核的SFs并预测相应的理论截面。系统计算表明，使用GSM衍生的SFs显著减少了理论与实验结果之间的差异。这种改进在接近滴线的核中特别显著，其中传统SM计算显得不足。因此，使用GSM SFs，R_s比率对ΔS没有明显的依赖性。此外，GSM SFs与SM SFs的比率及其对应的反应截面比率显示出对ΔS的强依赖性。我们还比较了GSM SFs和截面与无芯壳模型计算的结果，发现对ΔS的敏感性相似。详细分析将这些相关性归因于弱结合系统中SFs的阈值效应。总体而言，通过GSM纳入连续耦合增强了对奇异、弱结合核的SF预测的可靠性，并提供了从核结构角度解决重离子击出反应持久谜团的关键见解。

英文摘要：

A two-decade-old puzzle in heavy-ion one-nucleon knockout reactions is the strong correlation between the reduction factor $R_s=σ_{\rm exp}/σ_{\rm th}$ and the Fermi surface asymmetry $ΔS$. Theoretical cross sections typically rely on spectroscopic factors (SFs) from shell model (SM) calculations, which neglect continuum coupling effects. Here, we employ the Gamow shell model (GSM), which explicitly incorporates continuum coupling, to compute SFs for $p$-shell nuclei and predict corresponding theoretical cross sections. Systematic calculations demonstrate that using GSM-derived SFs substantially reduces discrepancies between theoretical and experimental results. This improvement is particularly significant for deeply bound nucleon knockout in nuclei near the dripline, where traditional SM-based calculations fall short. As a result, using GSM SFs, the ratio $R_s$ exhibits no pronounced dependence on $ΔS$. Furthermore, both the ratio of GSM SFs to SM SFs and their corresponding reaction cross sections ratios exhibit a strong $ΔS$ dependence. We have also compared GSM SFs and cross sections with those from the no-core shell model calculations, giving a similar pronounced sensitivity to $ΔS$. Detailed analysis attributes these correlations to threshold effects for SFs in weakly bound systems. Overall, incorporating continuum coupling via GSM enhances the reliability of SF predictions for exotic, weakly bound nuclei and provides key insights toward resolving the enduring puzzle in heavy-ion knockout reactions from a nuclear structure perspective.

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