Investigation of Resonances in the Di-Baryon System by Means of Data for Multi-Pion Production and Neutron-Proton Scattering

在这个项目中，将研究两个重子系统中共振的候选者。我们的出发点是在dpi0pi0通道中观察到同位旋-自旋-宇称i(JP)=0(3)的共振结构，这与几十年来已知的所谓ABC效应密切相关。这种结构出现在2.37GeV，即低于DeltaDelta阈值约90 MeV，宽度仅约70 MeV。自我们首次应用以来，我们成功地利用WASA数据揭示了所有NNpibi通道的共振结构以及在中子-质子散射中的共振结构，并在3D3分波中揭示了它的共振极点，从而证明它是真正的S通道共振，此后称为d*(2380)。进一步地，我们可以证明，没有观测到衰变到NNpi以及ABC效应有利于这个态是一个深度束缚的DeltaDelta态(紧致六夸克系统)。此外，我们还发现了存在等张量Deltan态D21的证据。本继续申请的目的是分析WASA数据以提取d*(2380)的电磁衰减通道，其提供关于该状态的结构的进一步信息，并最终更准确地呈现对i=3的预测的NN去耦合状态的搜索，以及为NNPIPI系统中相关的D12的产生寻找一致性原因。

In this project candidates for resonances in the system of two baryons shall be investigated. Starting point has been our observation of a resonance structure with isospin-spin-parity I(JP) = 0(3+) in the dpi0pi0 channel, which is tightly correlated with the so-called ABC effect known since decades. This structure appears at 2.37 GeV, i.e. about 90 MeV below the DeltaDelta threshold with a width of only about 70 MeV. Since our first application we succeeded to reveal the resonance structure in all NNpipi channels as well as in neutron-proton scattering with help of WASA data, reveal its resonance pole in the 3D3 partial wave and thus prove it as a true s-channel resonance, since then called d*(2380). Further-on we could demonstrate that the non-observation of a decay into NNpi as well as the ABC effect favor this state to be a deeply bound DeltaDelta state (compact hexaquark system). In addition we have found evidence for the existence of a isotensor DeltaN state, D21. Aim of this continuation application is the analysis of WASA data to extract electromagnetic decay channels of d*(2380), which provide further information about the structure of this state, and finally to render more precisely the search for a predicted NN-decoupled state with I=3, as well as to look for consistency reasons also for the associated production of D12 in NNpipi systems.