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

本研究的目的是在Faddeev形式的基础上，统一地阐明Pinn和etaNN系统的散射和反应的机制，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，利用相移分析结果，将输入的PIN相互作用表示为可分离的形式。此外，还考虑了Pin-Pn耦合、pidelta*N顶点和Pin_&lt；33&gt；相互作用的离壳自由度。输入这些元素，求解Faddeev方程。用统一的方法描述了PP-PP、NP-NP、PP-PID、PID和PP-Pnpi^+的过程，定量地与实验一致。在i=1，J^P=0^-通道中，在π阈值附近发现了一种由S波引起的介子结构。泡利原理禁止了I=0，J^P=0^-通道的NN态。因此，如果在该通道中的Pinn系统中存在共振，则其衰变宽度可能较窄。在pion阈值附近，我们计算了该通道中Pinn*Pinn过程的振幅。发现了窄至30 MeV的共振。这种态是由S波介子产生的。另一方面，在Pinn-etaNN系统中，由于S波介子在I=0，J^P=1^-通道中的阈值附近产生准束缚态。

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.