发表机构
University of Chinese Academy of Sciences; Institute of High Energy Physics, Chinese Academy of Sciences; International Centre for Theoretical Physics Asia-Pacific; Peking University（中国科学院大学; 中国科学院高能物理研究所; 亚洲太平洋理论物理中心; 北京大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究在非相对论QED框架下计算ep碰撞中排他性矢量轻子偶素电产生的NLO QCD修正，指出Bethe–Heitler过程主导产生率，支持在EIC和JLab搜寻双μ子素，正电子素可用于精密QED研究。
AI 中文摘要
纯轻子束缚态是量子电动力学（QED）的精密探针，正电子素（e⁺e⁻）和μ子素（μ⁺e⁻）已被长期观测，而双μ子素（μ⁺μ⁻）和τ子素（τ⁺τ⁻）尚未被发现。我们在非相对论QED框架下研究ep碰撞中的排他性矢量轻子偶素电产生，包含Bethe–Heitler过程、双深度虚康普顿散射（DDVCS）贡献及其干涉项，在共线GPD因子化方案中计算主导康普顿形状因子$\tilde{H}$对应的QCD次领头阶（NLO）硬散射内核。DDVCS贡献的NLO QCD修正随低虚光子截断升高，从低虚光子区的强压低转为显著增强，其中胶子道贡献占主导。Bethe–Heitler过程主导排他性产生率，支持在电子离子对撞机（EIC）和杰斐逊实验室（JLab）开展专门的双μ子素搜寻，更高能的ep对撞机将获得更多事例样本。正电子素的大样本为精密QED研究提供高统计环境，而τ子素产生仍被强压低。
英文摘要
Purely leptonic bound states provide precision probes of QED. Positronium $(e^+e^-)$ and muonium $(μ^+e^-)$ have long been observed, whereas dimuonium $(μ^+μ^-)$ and tauonium $(τ^+τ^-)$ remain undiscovered. We study exclusive vector-leptonium electroproduction in $ep$ collisions within nonrelativistic QED. We include the Bethe--Heitler and double deeply virtual Compton scattering contributions and their interference, and calculate the NLO QCD hard-scattering kernels entering the dominant Compton form factor $\Hcal$ within collinear GPD factorization. The NLO QCD correction to the DDVCS contribution changes from a strong suppression at low photon virtuality to a sizable enhancement as the lower virtuality cut is raised, with the gluon channel providing the dominant contribution. Bethe--Heitler production dominates the exclusive rate, supporting dedicated dimuonium searches at the EIC and JLab, with larger samples expected at higher-energy electron--proton colliders. The much larger positronium samples provide a high-statistics environment for precision QED studies, whereas tauonium production remains strongly suppressed.
Comments21 pages, 6 figures
