Structure of N^*(1535) and Δ(1232) with Electromagnetic Probe

用电磁探针观察 N^*(1535) 和 Δ(1232) 的结构

• 批准号: 12640273
• 负责人: SATO Toru
• 金额: $ 1.41万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640273/
• 关键词: Nucleon Resonance; Electron Scattering; Dion Production; Delta Resonance; ニュートリノ反応; 核子共嗚

An important challenge in nuclear research is to understand the hadron structure within QCD. One of the approach for pursuing this research is the study of the electromagnetic transition form factors of nucleon resonances. The purpose of this project is to extract the transition form factors. of Δ_<33> and N^*_<S11> resonances from the data of the electroproduction of meson.In this work we developed a dynamical reaction model on the electroproduction of mesons form the interaction Hamiltonian of meson and baryon with the method of unitary transformation. The predicted cross sections of the pion electropruduction were found to describe very well the extensive data from Jlab, Mainz and MIT-Bates.The results of our work are summarized as follows.1. Magnetic dipole(M1) form factor of NΔ transitionThe long standing discrepancy between empirically obtained M1 form factor and the prediction of quark models and also the very soft momentum dependence of the form factor were explained by the modification of the NΔ from factor due to the non-resonant rescattering mechanism.2. Electric quadrupole(E2,C2) form factor of NΔ transitionThe E2 and C2 form factors, which indicate the deformation of nucleon and delta, were shown to exist. In the high momentum transfer region the E1/M1 ratio was far small compared with the pQCD prediction. In the low momentum transfer region, we predicted a large contribution from the pion current. Those results have motivated proposal of new experiments.In the S_<11> region, we have developed effective Hamiltonian to describe two-pion prodo ion processes, and developed a numerical method to overcome difficulties due to the three-body scattering state using Wick-rotation.In summary we have shown the importance of dynamical approach to extract information on the nucleon resonance from the data of electroweak reactions.

在核研究中的一个重要挑战是理解QCD中的强子结构。进行这项研究的方法之一是研究核子共振的电磁跃迁形状因子。本项目的目的是提取过渡形式因素。本文从介子与重子相互作用的哈密顿量出发，利用么正变换的方法，建立了介子电产生的动力学反应模型。从JLAB、Mainz和MIT-Bates的大量数据可以很好地描述预测的π介子电学截面。我们的工作结果总结如下1.N-Δ跃迁的磁偶极子(M1)形状因子通过非共振再散射机制对N-Δ形状因子的修正，解释了经验性地获得的M1形状因子与夸克模型的预测之间的长期差异，以及形状因子与动量的非常弱的相关性。N-Δ跃迁的电四极(E_2，C_2)形状因子E_2和C_2形状因子被证明是存在的，它们表明核子和β的形变。在高动量传输区，E_1/M_1比pQCD预测的要小得多。在动量转移较低的区域，我们预测了π电流的很大贡献。这些结果促使了新实验的提出。在S区，我们发展了描述两π质子过程的有效哈密顿量，并发展了一种数值方法来克服由于三体散射态而产生的Wick-Rotation困难。综上所述，我们表明了从电弱反应数据中提取核子共振信息的动力学方法的重要性。

项目成果

T, -S.H.Lee, T.Sato: "Dynamical Model of Electroweak Pion Production Deactions"Few-Body Systems Suppl.. (in print).

T, -S.H.Lee, T.Sato：“弱电介子产生反应的动态模型”Few-Body Systems Supppl..（印刷中）。

T.sato: "Dynamical study of nucleonresonauces in πN and γN reactions"Nuclear Physics. A684. 26C (2001)

T.sato：“πN 和 γN 反应中核子共振的动力学研究”《核物理》A684。

T.Sato: "Pion Photo and Electro production in Dynamical Hodel"Proceedings of the physicals of Excited Nuclear. 75 (2001)

T.Sato：“动态霍德尔中的π介子光和电子产生”激发核物理学论文集。

T. Sato and T.-S. H. Lee: "Dynamical study of the Δ excitation in N(e, e^1π)) reactions"Physical Review. C63, 055201. 1-13 (2001)

T. Sato 和 T.-S. H. Lee：“N(e, e^1π)) 反应中 Δ 激发的动力学研究”《物理评论》C63，055201. 1-13 (2001)。

T. Sato: "Nuclear Physics with electron beam"Jour. of Plasma and Fusion Research. 77. 1122-1127 (2001)

T. Sato：“电子束核物理”杂志。