Low energy analysis of $\pi N$ scattering and the pion-nucleon sigma term with covariant baryon chiral perturbation theory
Low energy analysis of $\pi N$ scattering and the pion-nucleon sigma term with covariant baryon chiral perturbation theory
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发表时间：
2013-01
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通讯作者：
J. M. Alarc'on;J. Camalich;J. A. Oller
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作者：
J. M. Alarc'on;J. Camalich;J. A. Oller
π -核子σ项（$\sigma_{\pi N}$）是一个具有基本重要性的观测值，因为它体现了核子内部标量结构的信息。现在这个量已经引起了新的兴趣，因为它是可靠估计暗物质-核子不依赖自旋的弹性散射截面的关键输入。在这个过程中，我们提出了如何通过使用协变重子手性微扰理论，仅使用实验信息来可靠地提取这个量。我们还将我们的提取与与$\sigma_{\pi N}$相关的最新现象学进行了对比，并展示了这种现象学如何倾向于$\sigma_{\pi N}$的相对较大值。最后，我们从现代分波分析数据中提取了一个值$\sigma_{\pi N}=59(7)$ MeV。
The pion-nucleon sigma term ($\sigma_{\pi N}$) is an observable of fundamental importance because embodies information about the internal scalar structure of the nucleon. Nowadays this quantity has triggered renewed interest because it is a key input for a reliable estimation of the dark matter-nucleon spin independent elastic scattering cross section. In this proceeding we present how this quantity can be reliably extracted by employing only experimental information with the use covariant baryon chiral perturbation theory. We also contrast our extraction with updated phenomenology related to $\sigma_{\pi N}$ and show how this phenomenology favours a relatively large value of $\sigma_{\pi N}$. Finally, we extract a value of $\sigma_{\pi N}=59(7)$ MeV from modern partial wave analyses data.