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Theoretical research on S-wave meson-2 nucleon 3 body systems

横波介子2核子3体系统的理论研究

基本信息

批准号：
06640402
负责人：
UEDA Tamotsu
金额：
$ 1.34万
依托单位：
Ehime University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

The purpose of this research is to make clear the mechanisms for the scatterings and the reactions of the piNN and etaNN systems on a unified way based on the Faddeev formalism and to find characteristic phenomena such as dibaryons in these systems. Especially the phenomena which concern the S wave mesons are important subject.The piN interaction for input is represented in a separable form by use of phase-shift analysis results. On the other hand the NN interction is represented also in a separable form in an offshell equivalent way with Ueda-Green OBEP.Furthermore the piN-pN coupling, piDELTA*N vertex and the offshell freedom of the piN P_<33> interaction are taken into account. Faddeev equation is solved with these elements input. The processes of pp-pp, np-np, pp-pid, pid-pid, and pp-pnpi^+ are described in a unified way in quantitative consistence with experiment. A structure due tothe S wave pion is found near pion threshold in I=1, J^P=0^- channel.The Pauli principle forbids the NN state of I=0, J^P=0^- channel. Therefore, if a resonance exists in the piNN system in this channel, its decay width may be narrow. Near pion threshold we calculated the amplitude for piNN*piNN process in this channel. A resonance with such a narrow width as 30 MeV is found. This state is generated by S wave pion. On the other hand in piNN-etaNN system quasi bound state is generated due to S wave eta-meson near its threshold in I=0, J^P=1^- channel.

本研究的目的是在Faddeev形式主义的基础上统一地阐明piNN和etaNN系统的散射和反应机制，并发现这些系统中的特征现象，如双重子。特别是与S波介子有关的现象更是重要的研究课题，利用相移分析结果，将输入的π-N相互作用表示为可分离的形式。另一方面，利用Ueda-Green OBEP方法，将NN相互作用也表示为可分离的形式，并考虑了piN-pN耦合、piDELTA*N顶点和piN-P相互作用的离壳自由度<33>。Faddeev方程求解与这些元素的输入。对pp-pp、np-np、pp-pid、pid-pid和pp-pnpi^+过程进行了统一的描述，并与实验结果进行了定量的比较。在I=1，J^P=0^-通道中，在π介子阈值附近发现了一个由S波π介子引起的结构，泡利原理禁止I=0，J^P=0^-通道的NN态。因此，如果在该通道中的piNN系统中存在谐振，则其衰减宽度可能较窄。在π阈值附近，我们计算了该通道中piNN*piNN过程的幅度。发现了一个宽度为30 MeV的窄共振态，它是由S波π介子产生的。而在piNN-etaNN系统中，在I=0，J^P=1^-通道中，S波η介子在阈值附近产生准束缚态。