论文标题
ZRH22：在低能时对锥形核子测量的改进分析
ZRH22: An improved analysis of the pion-nucleon measurements at low energy
论文作者
论文摘要
在这项研究中进行的是对三个Pion-Nucleon（$πn$）反应的测量的改进分析，可以在低能（Pion实验室动能$ t \ leq 100 $ MEV）（即两个弹性分割（ES）处理$ fpe $ pm pm pm f \ f \ f \ f \ f \ f \ f \ f ppe^pm pm pm pm pm pm pm pm pm pp pm pm pm pm pm pm pm pm pm pm ppe^ - 电荷交换（CX）反应$π^-p \toπ^0 n $。在新分析程序的第一阶段的四个步骤应用后，该项目的新初始数据库（db）的$ 1150 $的条目中的$ 52 $条目被确定为离群物，并将其从输入中删除。以这种方式，获得了三个“清洁”（没有异常值）DB，这些DBS使用ETH模型提交了进一步分析。 ES测量值的相移分析（PSA）包括一百个关节拟合的结果，每个拟合都以一个值进行（根据最新结果，按正态分布随机生成，根据$M_σ$）与$πn$ $πn$相互作用的标量 - iSscalar部分的有效范围相关。 ES数据的PSA的结果（已带电的 - 平方耦合常数$ f_c $是：$ f_c^2 = 0.0764（15）$。 ETH模型对低能$π^-p $ cx db的独家拟合度在近年来抑制了ETH模型的部分波振幅后，这也是第一次进行，该模型源自标量 - iSoscalar $ t $ t $ t $ t $ channel feynman图。 The predictions, obtained from these two types of fits (PSA of the ES data and exclusive fit of the ETH model to the $π^- p$ CX DB) for the (popular) symmetrised relative difference $R_2$ were compared in the entire low-energy region, separately for the $s$ wave, as well as for the no-spin-flip and spin-flip $p$-wave parts of the $πN$ scattering amplitude.
Carried out in this study is an improved analysis of the measurements of the three pion-nucleon ($πN$) reactions, which can be subjected to experimental investigation at low energy (pion laboratory kinetic energy $T \leq 100$ MeV), i.e., of the two elastic-scattering (ES) processes $π^\pm p \to π^\pm p$ and of the $π^- p$ charge-exchange (CX) reaction $π^- p \to π^0 n$. After the application of the four steps of the first phase of the new analysis procedure, $52$ entries - of the $1150$ degrees of freedom of the new initial database (DB) of this project - were identified as outliers and were removed from the input. In this manner, three `clean' (devoid of outliers) DBs were obtained, which were submitted to further analysis using the ETH model. The phase-shift analysis (PSA) of the ES measurements comprises the results of one hundred joint fits to the data, each fit being carried out at one value (randomly generated, in normal distribution, according to a recent result) of the model parameter $m_σ$, which is associated with the effective range of the scalar-isoscalar part of the $πN$ interaction. The result of the PSA of the ES data for the (square of the) charged-pion coupling constant $f_c$ is: $f_c^2=0.0764(15)$. An exclusive fit of the ETH model to the low-energy $π^- p$ CX DB was also performed, for the first time in the recent years, after suppressing the contributions to the partial-wave amplitudes of the ETH model which originate from the scalar-isoscalar $t$-channel Feynman diagram. The predictions, obtained from these two types of fits (PSA of the ES data and exclusive fit of the ETH model to the $π^- p$ CX DB) for the (popular) symmetrised relative difference $R_2$ were compared in the entire low-energy region, separately for the $s$ wave, as well as for the no-spin-flip and spin-flip $p$-wave parts of the $πN$ scattering amplitude.
