深度非弹性散射中的非全局对数与基准横向动量依赖观测量

中文摘要 AI 辅助

从深度非弹性散射数据中提取夸克的内在横向动量结构，需要将非微扰效应与展宽所测横向动量分布的微扰辐射分离开来。我们在电子-质子散射 $ep\to eX$ 中处理这一问题，引入基准不平衡量 $\boldsymbol{q}_T$，定义为散射电子横向动量与指定快度窗口内所有强子横向动量的矢量和。该构造无需喷注重建或显式喷注否决即可减少辐射反冲。我们考虑了由接受边界上的关联软发射产生的非全局对数（NGL）。方位角平均的NGL贡献在领头对数精度下、在大$N_c$极限内，通过Banfi--Marchesini--Smye演化进行全阶重求和，而第一个方位角谐波的领头NGL修正则包含在$\mathcal{O}(\alpha_s^2)$阶。对于所考虑的EIC和EicC运动学，加宽快度窗口会增加低$q_T$区域的截面，该区域对非微扰横向动力学特别敏感，并减少方位角对称软反冲对自旋不对称性的稀释。Sivers单自旋不对称性$A_{UT}$和蜗轮双自旋不对称性$A_{LT}$的幅度均增大，而$\boldsymbol{q}_T$积分截面保持不变。由软胶子辐射产生的非极化$\cos\phi$矩对NGL效应敏感，其比值定义减少了常见的归一化不确定性。无需喷注重建使得该观测量在EicC较低碰撞能量下尤为相关，提供了一种通过改变基准接受度来研究非微扰自旋-动量关联的途径。

英文摘要

Extracting the intrinsic transverse-momentum structure of quarks from deep-inelastic scattering data requires separating nonperturbative effects from perturbative radiation, which broadens the measured transverse-momentum distributions. We address this problem in electron--proton scattering, $ep\to eX$, by introducing the fiducial imbalance $\boldsymbol{q}_T$, defined as the vector sum of the scattered electron's transverse momentum and all hadronic transverse momenta within a specified rapidity window. This construction reduces radiative recoil without requiring jet reconstruction or an explicit jet veto. We account for non-global logarithms (NGLs) arising from correlated soft emissions across the acceptance boundary. The azimuthally averaged NGL contribution is resummed to all orders at leading-logarithmic accuracy in the large-$N_c$ limit using Banfi--Marchesini--Smye evolution, while the leading NGL correction to the first azimuthal harmonic is included at $\mathcal{O}(α_s^2)$. For the EIC and EicC kinematics considered, widening the rapidity window increases the cross section at low $q_T$, a region particularly sensitive to nonperturbative transverse dynamics, and reduces the dilution of spin asymmetries by azimuthally symmetric soft recoil. Both the Sivers single-spin asymmetry $A_{UT}$ and the worm-gear double-spin asymmetry $A_{LT}$ increase in magnitude, while the $\boldsymbol{q}_T$ integrated cross section remains unchanged. The unpolarized $\cosϕ$ moment generated by soft gluon radiation is sensitive to NGL effects, with its ratio definition reducing common normalization uncertainties. The absence of jet reconstruction makes this observable particularly relevant at the lower collision energies of EicC, providing a way to study nonperturbative spin--momentum correlations by varying the fiducial acceptance.

发表机构

• Shandong University（山东大学）
• Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）

机构由 AI 辅助整理，请以论文原文为准。