AI 中文总结
本研究利用CLAS探测器数据和JM反应模型，首次得到第三共振区核子共振的电耦合结果，证实了反应模型的提取能力，为强QCD机制研究提供新机遇。
AI 中文摘要
本文给出了第三共振区核子共振（N*）的电激发振幅或γᵥpN*电耦合的首批结果。这些结果来自用CLAS探测器测量的π⁺π⁻p电产生微分截面，并采用杰斐逊实验室-莫斯科国立大学（JM）反应模型进行分析。分析涵盖了末态强子的不变质量范围W为1.56至1.76 GeV，以及虚光子四动量平方Q²为2.0至5.0 GeV²。通过对πN和π⁺π⁻p两种末态的独立分析，得到了N(1675)5/2⁻和N(1680)5/2⁺电激发振幅的一致结果，证明了反应模型提取第三共振区N*的γᵥpN*电耦合的能力。此外，首次获得了主要衰变为ππN末态的Δ(1700)3/2⁻和N(1720)3/2⁺在Q²>2.0 GeV²时的电耦合数据。最后，在Q²<5.0 GeV²时，观测到新的N'(1720)3/2⁺重子态对π⁺π⁻p微分截面的贡献。第三共振区共振电耦合的新结果为探索产生核子激发态的强QCD机制的各个方面提供了新机遇，特别是有助于理解与动力学手征对称性破缺相关的强子质量的产生。
英文摘要
The first results on the electroexcitation amplitudes or the $γ_vpN^*$ electrocouplings for nucleon resonances ($N^*$s) in the third resonance region are presented. They were obtained from $π^+π^-p$ electroproduction differential cross sections measured with the CLAS detector and analyzed using the Jefferson Lab-Moscow State University (JM) reaction model. The analysis covers the invariant mass range of the final-state hadrons $W$ from 1.56 to 1.76~GeV and virtual photon four-momentum squared $Q^2$ from 2.0 to 5.0~GeV$^2$. Consistent results on the electroexcitation amplitudes of the $N(1675)5/2^-$ and $N(1680)5/2^+$ obtained from independent analyses of both $πN$ and $π^+π^-p$ final states, demonstrate the capability of reaction models to extract the $γ_v p N^*$ electrocouplings for $N^*$s in the third resonance region. Also, for the first time, the electrocouplings of the $Δ(1700)3/2^-$ and $N(1720)3/2^+$, which predominantly decay into $ππN$ final states, have become available for $Q^2 > 2.0$~GeV$^2$. Finally, contributions from a new $N'(1720)3/2^+$ baryon state to the $π^+π^-p$ differential cross sections have been observed for $Q^2 < 5.0$~GeV$^2$. The new results on resonance electrocouplings in the third resonance region offer new opportunities to explore various aspects of the strong QCD regime responsible for the generation of nucleon excited states, in particular, shedding light on the emergence of hadron mass in connection with dynamical chiral symmetry breaking.
Comments25 pages, 18 figures
