论文标题
从过去三十年来对低能Pion-Nucleon数据的分析中学到了什么？
What has been learnt from the analysis of the low-energy pion-nucleon data during the past three decades?
论文作者
论文摘要
二十五年前，在低能（即，对于Pion实验室动能$ t \ leq 100 $ MEV）的Pion-Nucleon（$πn$）数据进行了两次分析，这些分析涉及提取的散射振幅的出发电荷交换反应$π^ - p \toπ^0 n $，从三角形身份中，如果isospin不变性在$πn$相互作用的辐射部分中成立，则这些振幅就能实现。此差异表明\ emph {至少一个假设中的一个}是无效的：首先，低能量$πn$数据集的绝对正常化是正确的；其次，旨在从测量中去除电磁（EM）起源的效果的任何残余贡献都不显着；第三，同义不变性在$πn$相互作用的HADRONIC部分中。 In view of the incompatibility of the results of the various schemes of removal of the so-called trivial EM effects at the $πN$ threshold ($T = 0$ MeV), the likelihood of residual effects of EM origin in the extracted $πN$ scattering amplitudes (from the data in the scattering region, i.e., above the $πN$ threshold) must be reassessed.这项工作强调了开发统一方案在确定可靠的EM校正的重要性，\ emph {适用于$πn$阈值和散射区域}，以解决低能量的确定差异。
Over twenty-five years ago, two analyses of the pion-nucleon ($πN$) data at low energy (i.e., for pion laboratory kinetic energy $T \leq 100$ MeV) reported on the departure of the extracted scattering amplitudes, corresponding to the two elastic-scattering reactions $π^\pm p \to π^\pm p$ and to the $π^- p$ charge-exchange reaction $π^- p \to π^0 n$, from the triangle identity, which these amplitudes fulfil if the isospin invariance holds in the hadronic part of the $πN$ interaction. This discrepancy indicates that \emph{at least one} of the following assumptions is not valid: first, that the absolute normalisation of the bulk of the low-energy $πN$ datasets is correct; second, that any residual contributions to the corrections, which aim at the removal of the effects of electromagnetic (EM) origin from the measurements, are not significant; and third, that the isospin invariance holds in the hadronic part of the $πN$ interaction. In view of the incompatibility of the results of the various schemes of removal of the so-called trivial EM effects at the $πN$ threshold ($T = 0$ MeV), the likelihood of residual effects of EM origin in the extracted $πN$ scattering amplitudes (from the data in the scattering region, i.e., above the $πN$ threshold) must be reassessed. This work emphasises the importance of the development of a unified scheme for the determination of reliable EM corrections, \emph{applicable at the $πN$ threshold and in the scattering region}, in providing a resolution to the established discrepancy at low energy.
