The pion–nucleon sigma term is a quantity involved in many important aspects of particle and nuclear physics. In this review, I show its origin and how it is connected to important questions as the origin of mass of the ordinary matter, studies of dark matter detection and nucleosynthesis. I mention the most common methods used to obtain the sigma term, and comment on the extracted values. As it is shown, the accepted value of the sigma term has been moving from relatively low (\(\sim 40\) MeV) to larger ones (\(\sim 60\) MeV) until today, where this controversy still persist.

中文翻译：

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pion-nucleon sigma 术语的简史

pion-nucleon sigma 项是一个涉及粒子和核物理许多重要方面的量。在这篇综述中，我展示了它的起源，以及它如何与普通物质的质量起源、暗物质探测和核合成研究等重要问题联系起来。我提到了用于获取 sigma 项的最常用方法，并对提取的值进行了评论。如图所示，西格玛项的公认值一直从相对较低的 ( \(\sim 40\)  MeV) 移动到更大的值 ( \(\sim 60\)  MeV)，直到今天，这一争议仍然存在。