The standard way to demonstrate the relevance of chiral symmetry for the NN interaction is to consider higher partial waves of NN scattering which are controlled entirely by chiral pion-exchanges (since contacts vanish). However, in applications of NN -potentials to nuclear structure and reactions, the lower partial waves are the important ones, making the largest contributions. Lower partial waves are sensitive to the short-range potential, and so, when the short-range contacts were to dominate over the chiral pion-contributions in lower partial waves, then the predictions from “chiral potentials” would have little to do with chiral symmetry. To address this issue, we investigate systematically the role of the (chiral) one- and two-pion exchanges, on the one hand, and the effect of the contacts, on the other hand, in the lower partial waves of NN scattering. We are able to clearly identify the signature of chiral symmetry in lower partial waves. Our study has also a pedagogical spin-off as it demonstrates in detail how the reproduction of the lower partial-wave phase shifts comes about from the various ingredients of the theory.

中文翻译：

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核子-核子散射的手性有效场论描述中π-交换贡献与接触项的相关性

证明手性对称性与 NN 相互作用相关性的标准方法是考虑 NN 散射的更高部分波，这些波完全由手性 pion 交换控制（因为接触消失）。然而，在 NN 势在核结构和反应中的应用中，较低的分波是重要的，做出了最大的贡献。低分波对短程电位敏感，因此，当短程接触支配低分波中的手性π贡献时，“手性电位”的预测将与手性关系不大。对称。为了解决这个问题，我们一方面系统地研究了（手性）一个和两个 pion 交换的作用，另一方面研究了接触的影响，在 NN 散射的较低部分波中。我们能够清楚地识别较低分波中的手征对称性特征。我们的研究还有一个教学衍生，因为它详细展示了较低分波相移的再现是如何从理论的各种成分中产生的。