Pion Production by Neutron Beam

The pion production pn → pp πイD1-イエD1 and pp → pp πイD10イエD1 were discussed。“理论分析是通过使用重型介子交换和核潜艇模型进行的，包括核共振的影响。”对于所有的充电通道，模型的工作从近阈值（s波振幅）到Δ能量区（p波振幅）。pion-production cross sections are decomposed to four independent isospin·itudes T-D2IiIf-D2 which represents the transition from an initial two nucleon state with isospin I-D2i-D2 to a final state with isospin I-D2f-D2。The reaction pp → pp πイイD10イエD1 is characterized by the Oracle itude TイイD211イエD2 which is mainly determined by the s-waveイD2 πイエD2N interaction。Contrary to this， the reaction pn → pp··D1-·D1 depends on both the s-wave·itude T·D211··D2 and the p-wave·itude T·D201·D2。- -和p波之间的相互作用导致了不同交叉部分的前向-后向不对称。The最近的作品with the chiral perturbation theory predict the s-wave amplitude with the opposite sign to the results of the heavy-meson exchange model and the pion-rescattering model because the s-wave amplitude of the chiral perturbation theory changes its when going from on-shell to half-off-shell kinematics。However， the models with opposite signof s-wave fail to explain the angular dependence of pn → pp πイイD1-イエD1 reaction。我们还讨论了以下两个主题有关P10的D1 production。（1）角度分布对Δ激发机制的短程结构非常敏感。（2）对分析功率建议的测量，即较大的S波振幅即使在高能量区域也是必要的。

The pion production pn → ppπィイD1-ィエD1 and pp → ppπィイD10ィエD1 were discussed. The theoretical analysis has been performed by using the models of heavy-meson exchange and pion-rescattering including the effect of nucleon resonances. For all the charge channels, the models work well from the near-threshold (s-wave amplitude) to the Δ energy region (p-wave amplitude). The pion-production cross sections are decomposed to four independent isospin amplitudes TィイD2IiIfィエD2 which represents the transition from an initial two nucleon state with isospin IィイD2iィエD2 to a final state with isospin IィイD2fィエD2. The reaction pp → ppπィイD10ィエD1 is characterized by the amplitude TィイD211ィエD2 which is mainly determined by the s-wave ィイD2πィエD2N interaction. Contrary to this, the reaction pn → ppπィイD1-ィエD1 depends on both the s-wave amplitude TィイD211ィエD2 and the p-wave amplitude TィイD201ィエD2. The interference between s- and p-wave causes the forward-backward asymmetry of the differential cross section. The recent works with the chiral perturbation theory predict the s-wave amplitude with the opposite sign to the results of the heavy-meson exchange model and the pion-rescattering model because the s-wave amplitude of the chiral perturbation theory changes its sign when going from on-shell to half-off-shell kinematics. However, the models with opposite sign of s-wave fail to explain the angular dependence of pn → ppπィイD1-ィエD1 reaction. We also discuss about following two topics about πィイD10ィエD1 production. 1) The angular distribution is very sensitive to the short range structure of Δ-excitation mechanism. 2) The measurement of analyzing power suggests that large s-wave amplitude is necessary even at higher energy region.