电子离子对撞机上的极化喷注各向异性
Polarized jet anisotropy at the Electron-Ion Collider
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中文总结 AI 辅助
该研究针对电子离子对撞机，利用横动量依赖量子色动力学因子化方法，揭示喷注诱导的各向异性对极化不对称性的宇称选择规则，为核子结构精确提取提供新可观测量。
中文摘要 AI 辅助
喷注是研究核子三维自旋结构的有力探针，而核子三维自旋结构是电子离子对撞机（Electron-Ion Collider，EIC）的核心目标。然而观测到的喷注定义了一个轴，该轴会破坏软胶子辐射的方位各向同性，进而改变用于提取核子三维自旋结构的不对称性。利用横动量依赖（Transverse-Momentum-Dependent，TMD）量子色动力学（QCD）因子化方法，我们首次证明这种喷注诱导的各向异性会对极化不对称性施加宇称选择规则。将横极化结构函数展开为谐波cos(nφ_qJ)，其中φ_qJ是喷注与轻子-喷注动量不平衡之间的夹角，可明确该规则：每个谐波的对称性由n的奇偶性决定，与谐波系数的大小无关。对于Sivers函数，质子自旋相关的典型左右不对称性在n为偶数时保留，而在n为奇数时则变为反直觉的左右对称性；worm-gear函数在所有谐波下均保留上下不对称性，且在n为偶数时左右对称、n为奇数时左右不对称。在EIC运动学区域，本文研究的高阶谐波被预测可单独测量，为软辐射的方位动力学提供了新的可观测量，也是精确提取核子结构的关键要素。
英文摘要
Jets provide a powerful probe of the three-dimensional spin structure of the nucleon, a central goal of the Electron-Ion Collider. Yet the observed jet defines an axis that breaks the azimuthal isotropy of soft-gluon radiation, thereby reshaping the very asymmetries used to extract that structure. Using transverse-momentum-dependent (TMD) QCD factorization, we show for the first time that this jet-induced anisotropy imposes a parity selection rule on polarized asymmetries. Expanding the transversely polarized structure functions in harmonics $\cos(nϕ_{qJ})$, where $ϕ_{qJ}$ is the angle between the jet and the lepton-jet momentum imbalance, makes this rule explicit: the symmetry of each harmonic is fixed by the parity of $n$, independently of the magnitudes of the harmonic coefficients. For the Sivers function, the canonical left-right asymmetry about the proton spin survives for even $n$ but is replaced by a counterintuitive left-right symmetry for odd $n$. The worm-gear function retains its up-down asymmetry at every harmonic while being left-right symmetric for even $n$ and asymmetric for odd $n$. At EIC kinematics, the higher harmonics studied here are predicted to be individually measurable, providing new observables for the azimuthal dynamics of soft radiation and an essential ingredient in precision extractions of nucleon structure.
发表机构
- University of California, Los Angeles（加州大学洛杉矶分校）
- Mani L. Bhaumik Institute for Theoretical Physics, University of California, Los Angeles（加州大学洛杉矶分校马尼·L·巴乌米克理论物理研究所）
- Stony Brook University（石溪大学）
- South China Normal University（华南师范大学）
- Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）
- Massachusetts Institute of Technology（麻省理工学院）
- University of Chinese Academy of Sciences（中国科学院大学）
机构由 AI 辅助整理，请以论文原文为准。
