发表机构
Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine（鲍戈留博夫理论物理研究所，乌克兰国家科学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文研究近阈值 $J/\psi$ 产生中核子标量与自旋二色电结构的简并问题，发现现有截面数据无法唯一确定标量贡献，需借助极化敏感可观测量和复螺旋度振幅来约束相对相位。
AI 中文摘要
近阈值 $J/\psi$ 产生对核子中的标量和无迹自旋二色电结构敏感。我们研究现有的积分和微分测量能否区分这些贡献并约束它们的相对相位。GlueX 积分截面不能确定唯一的标量贡献：产生项和弹性标量项强相关，而更平坦的非前向轮廓将拟合的标量强度驱动至零。在包含 38 个数据点的大 $\xi$ 微分分析中，标量项在固定运动学下与保留的 C-GFF 方向共线，导致近似简并的解和强烈的轮廓依赖性。一个共同的单通道末态因子保持标量与自旋二的相对相位，而耦合道重散射可以修改它。因此，其确定需要极化敏感可观测量以及过程特定的复螺旋度振幅。
英文摘要
Near-threshold $J/ψ$ production is sensitive to scalar and traceless spin-two chromoelectric structure in the nucleon. We study whether present integrated and differential measurements can separate these contributions and constrain their relative phase. The GlueX integrated cross section does not determine a unique scalar contribution: production and elastic scalar terms are strongly correlated, while flatter non-forward profiles drive the fitted scalar strength to zero. In a 38-point large-$ξ$ differential analysis, the scalar term is collinear at fixed kinematics with the retained C-GFF direction, leading to nearly degenerate solutions and strong profile dependence. A common single-channel final-state factor preserves the scalar-spin-two relative phase, whereas coupled-channel rescattering can modify it. Its determination therefore requires polarization-sensitive observables together with process-specific complex helicity amplitudes.
Comments13 pages, 4 figures
