发表机构
The University of Tokyo（东京大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文利用引力横向动量分布研究小-x胶子和海夸克的动量空间力学性质，推导胶子分布与普通TMD的关系，并通过数值计算揭示其偏离自由粒子关系的行为。
AI 中文摘要
我们利用引力横向动量分布（gravitational TMDs）研究小-$x$ 胶子和海夸克的动量空间力学性质。对于胶子，我们使用光前规范不变的规范能量-动量张量来构造这些分布，并推导它们与普通 TMD 关联函数的关系，识别出动量密度、惯性的横向通量和横向应力。在 eikonal 近似下，纵向和横向的规范胶子动量密度由非极化分布决定，而惯性的横向通量和横向应力为零。对于非极化靶，我们基于 McLerran--Venugopalan 模型和固定耦合领头阶 Balitsky--Kovchegov 演化，使用共同的初始条件数值评估胶子和海夸克的动量密度。我们还通过高横向动量区域的 twist-3 夸克 TMD 评估海夸克的惯性横向通量。这些结果展示了规范横向动量与支配惯性流动的有效横向速度之间偏离自由粒子关系的情况。
英文摘要
We investigate the momentum-space mechanical properties of small-$x$ gluons and sea quarks using gravitational transverse-momentum distributions (gravitational TMDs). For gluons, we formulate these distributions using the light-front gauge-invariant canonical energy-momentum tensor and derive their relations to ordinary TMD correlators, identifying momentum densities, the transverse flux of inertia, and transverse stresses. In the eikonal approximation, the longitudinal and transverse canonical gluon momentum densities are determined by the unpolarized distribution, whereas the transverse flux of inertia and transverse stresses vanish. For an unpolarized target, we numerically evaluate the gluon and sea-quark momentum densities using a common initial condition based on the McLerran--Venugopalan model and fixed-coupling leading-order Balitsky--Kovchegov evolution. We also evaluate the sea-quark transverse flux of inertia through the twist-three quark TMD at the high transverse-momentum region. These results illustrate departures from the free-particle relation between canonical transverse momentum and the effective transverse velocity governing inertia flow.
Comments17 pages, 5 figures
