AI 中文总结
本文通过自旋密度矩阵研究高能散射中重夸克对的纠缠与贝尔非定域性，发现相干衍射产生中最大纠缠点及饱和效应对方位角调制的抑制，连接量子信息与坡密子物理。
AI 中文摘要
自旋关联为高能散射中产生的部分子末态提供了量子信息视角。我们讨论了两种互补的小$x$过程中的重夸克-反夸克对的自旋密度矩阵。在相干衍射产生中，色单态交换强制了纠缠与贝尔非定域性之间异常强的联系：纵向光子产生最大纠缠对，而横向光子产生的对通常既纠缠又贝尔非定域，并存在一个模型无关的最大纠缠点。在包含背对背产生中，密度矩阵分解为硬自旋张量和非极化及线性极化的Weizsäcker-Williams胶子分布。后者产生方位角调制，并且当双喷注相对动量和不平衡近似正交时，可以增加并发度。引人注目的是，在所考虑的饱和模型中，非线性效应在$q_\perp\lesssim 3Q_s$时抹去了这种调制，而稀释的BFKL极限（其中$G_2/G_0\to1$）产生与不平衡大小无关的最大调制。这些结果将量子信息可观测量与坡密子及饱和物理联系起来。
英文摘要
Spin correlations offer a quantum-information perspective on the partonic final states produced in high-energy scattering. We discuss the spin-density matrix of a heavy quark-antiquark pair in two complementary small-$x$ processes. In coherent diffractive production, color-singlet exchange enforces an unusually strong relation between entanglement and Bell nonlocality: a longitudinal photon creates a maximally entangled pair, whereas for a transverse photon the pair is generically both entangled and Bell nonlocal, with a model-independent point of maximal entanglement. In inclusive back-to-back production, the density matrix factorizes into a hard spin tensor and the unpolarized and linearly polarized Weizsäcker--Williams gluon distributions. The latter generates an azimuthal modulation and can increase the concurrence when the dijet relative momentum and imbalance are approximately orthogonal. Strikingly, in the saturation model considered, nonlinear effects wash out this modulation for $q_\perp\lesssim 3Q_s$, whereas the dilute BFKL limit, in which $G_2/G_0\to1$, yields a maximal modulation independent of the imbalance magnitude. These results connect quantum-information observables with the Pomeron and saturation physics.
Comments7 pages, 2 figures. Proceedings of the 33rd International Workshop on Deep Inelastic Scattering and Related Subjects (DIS2026), 4-8 May 2026, Bologna, Italy
