Elastic \(^{16}\hbox {O}+^{12}\hbox {\!\!C}\) scattering is known to exhibit the nuclear rainbow pattern at incident energies \(E_\text {lab} > rsim 200\) MeV, with the Airy structure of the far-side scattering cross section clearly seen at medium and large angles. Such a rainbow pattern is well described by the deep real optical potential (OP) given by the double-folding model (DFM). At lower energies, the extensive elastic \(^{16}\hbox {O}+^{12}\hbox {\!\!C}\) scattering data show consistently that the nuclear rainbow pattern at backward angles is deteriorated by an oscillating enhancement of elastic cross section that is difficult to describe in the conventional optical model (OM). Given a significant \(\alpha \) spectroscopic factor predicted for the dissociation \(^{16}\)O\(\rightarrow \alpha +^{12}\)C by the shell model and \(\alpha \)-cluster models, the contribution of the elastic \(\alpha \) transfer (or the core-core exchange) to the elastic \(^{16}\hbox {O}+^{12}\hbox {\!\!C}\) scattering should not be negligible and is expected to account for the enhanced elastic cross section at backward angles. To reveal the impact of the elastic \(\alpha \) transfer, a systematic coupled reaction channels analysis of the elastic \(^{16}\hbox {O}+^{12}\hbox {\!\!C}\) scattering has been performed, with the coupling between the elastic scattering and elastic \(\alpha \) transfer channels treated explicitly, using the real OP given by the DFM. We found that the elastic \(\alpha \) transfer enhances the near-side scattering significantly at backward angles, giving rise to an oscillating distortion of the smooth Airy structure. The dynamic polarization of the OP by the coupling between the elastic scattering and elastic \(\alpha \) transfer channels can be effectively taken into account in the OM calculation by an angular-momentum (or parity) dependent potential added to the imaginary OP, as suggested by Frahn and Hussein 40 years ago.

已知弹性\（^ {16} \ hbox {O} + ^ {12} \ hbox {\！\！C} \）散射在入射能量下表现出核彩虹图案\（E_ \ text {lab}> rsim 200 \） MeV，在中大角度都能清楚地看到远侧散射截面的Airy结构。双重折叠模型（DFM）给出的深真实光学势能（OP）很好地描述了这种彩虹图案。在较低的能量下，广泛的弹性\（^ {16} \ hbox {O} + ^ {12} \ hbox {\！\！C} \）散射数据一致地显示，后向角的核彩虹图案会由于弹性横截面的振荡增强，这在常规光学模型（OM）中很难描述。给定一个重要的\（\ alpha \）壳模型和\（\ alpha \）-聚类模型预测的解离\（^ {16} \） O \（\ rightarrow \ alpha + ^ {12} \） C的光谱因子，弹性\ （\ alpha \）转移（或核心-核心交换）到弹性\（^ {16} \ hbox {O} + ^ {12} \ hbox {\！\！C} \）的散射不可忽略，并且可以预期在向后角度时弹性横截面增大。为了揭示弹性\（\ alpha \）传递的影响，对弹性\（^ {16} \ hbox {O} + ^ {12} \ hbox {\！\！C} \的系统耦合反应通道分析）已经执行了散射，弹性散射和弹性之间的耦合\（\ alpha \）传输通道使用DFM给定的实际OP进行了显式处理。我们发现，弹性\（\ alpha \）传递在向后角度显着增强了近侧散射，从而引起了光滑的Airy结构的振荡变形。在OM计算中，可以通过将与角动量（或奇偶校验）相关的电势加到虚部OP上，有效地考虑通过弹性散射和弹性\（\ alpha \）传输通道之间的耦合而产生的OP的动态极化，正如Frahn和Hussein在40年前所建议的那样。