Abstract The analysis of the nine 1-fold differential cross sections for the γ r , v p → π + π − p photo- and electroproduction reactions obtained with the CLAS detector at Jefferson Laboratory was carried out with the goal to establish the contributing resonances in the mass range from 1.6 GeV to 1.8 GeV. In order to describe the photo- and electroproduction data with Q 2 -independent resonance masses and hadronic decay widths in the Q 2 range below 1.5 GeV2, it was found that an N ′ ( 1720 ) 3 / 2 + state is required in addition to the already well-established nucleon resonances. This work demonstrates that the combined studies of π + π − p photo- and electroproduction data are vital for the observation of this resonance. The contributions from the N ′ ( 1720 ) 3 / 2 + state and the already established N ( 1720 ) 3 / 2 + state with a mass of 1.745 GeV are well separated by their different hadronic decays to the πΔ and ρp final states and the different Q 2 -evolution of their photo-/electroexcitation amplitudes. The N ′ ( 1720 ) 3 / 2 + state is the first recently established baryon resonance for which the results on the Q 2 -evolution of the photo-/electrocouplings have become available. These results are important for the exploration of the nature of the “missing” baryon resonances.

中文翻译：

---

N'(1720)3/2+ 核子共振的证据来自 CLAS π+π−p 光和电生产数据的联合研究

摘要 对使用杰斐逊实验室的 CLAS 探测器获得的 γ r , vp → π + π − p 光和电生产反应的 9 个 1 倍微分截面进行了分析，目的是确定在质量范围从 1.6 GeV 到 1.8 GeV。为了描述与 Q 2 无关的共振质量和强子衰减宽度在低于 1.5 GeV2 的 Q 2 范围内的光和电生产数据，发现除了需要 N ' (1720 ) 3 / 2 + 状态之外已经完善的核子共振。这项工作表明，π + π − p 光和电生产数据的联合研究对于观察这种共振至关重要。来自 N ' (1720) 3 / 2 + 状态和已经建立的质量为 1 的 N (1720) 3 / 2 + 状态的贡献。745 GeV 因它们不同的强子衰变到 πΔ 和 ρp 最终状态以及它们的光/电激发振幅的不同 Q 2 演化而被很好地分开。N ' (1720) 3 / 2 + 状态是最近建立的第一个重子共振，光耦合/电耦合的 Q 2 演化结果已经可用。这些结果对于探索“缺失”重子共振的性质很重要。