The primary experimental goal of studies of hadronic parity nonconservation (PNC) has long been the isolation of the isovector weak nucleon–nucleon interaction, expected to be dominated by long-range pion exchange and enhanced by the neutral current. In meson-exchange descriptions, this interaction, together with an isoscalar interaction generated by and exchange, dominates most observables. Both amplitudes have been used to compare and check the consistency of experiments, yet no evidence for isovector hadronic PNC has been found. We argue that the emphasis on isovector hadronic PNC was misplaced. The large- expansion provides an alternative and theoretically better-motivated simplification of effective field theories (EFTs) of hadronic PNC, separating the five low-energy constants (LECs) into two of leading order (LO) and three of next-to-next-to-leading order (NLO). We show that this large- LEC hierarchy accurately describes all existing data on hadronic PNC and discuss opportunities to further test th...

中文翻译：

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强子奇偶不守恒的新范式及其实验意义

强子奇偶不守恒 (PNC) 研究的主要实验目标长期以来一直是隔离等向量弱核子 - 核子相互作用，预计由远程 pion 交换主导并由中性电流增强。在介子交换的描述中，这种相互作用，连同由 和 交换产生的等标相互作用，支配着大多数可观察的事物。两种振幅都已用于比较和检查实验的一致性，但尚未发现等向量强子 PNC 的证据。我们认为对等向量强子 PNC 的强调是错误的。大展开为强子 PNC 的有效场论 (EFT) 提供了一种替代的、理论上有更好动机的简化，将五个低能量常数 (LEC) 分为两个领先顺序 (LO) 和三个次一领先 (NLO)。我们展示了这个大 LEC 层次结构准确地描述了强子 PNC 的所有现有数据，并讨论了进一步测试......