First measurements of balance functions (BFs) of all combinations of identified charged hadron $(\pi ,\mathrm{K},\mathrm{p})$ pairs in Pb–Pb collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=2.76$ TeV recorded by the ALICE detector are presented. The BF measurements are carried out as two-dimensional differential correlators versus the relative rapidity (Δy) and azimuthal angle (Δφ) of hadron pairs, and studied as a function of collision centrality. The Δφ dependence of BFs is expected to be sensitive to the light quark diffusivity in the quark–gluon plasma. While the BF azimuthal widths of all pairs substantially decrease from peripheral to central collisions, the longitudinal widths exhibit mixed behaviors: BFs of ππ and cross-species pairs narrow significantly in more central collisions, whereas those of KK and pp are found to be independent of collision centrality. This dichotomy is qualitatively consistent with the presence of strong radial flow effects and the existence of two stages of quark production in relativistic heavy-ion collisions. Finally, the first measurements of the collision centrality evolution of BF integrals are presented, with the observation that charge balancing fractions are nearly independent of collision centrality in Pb–Pb collisions. Overall, the results presented provide new and challenging constraints for theoretical models of hadron production and transport in relativistic heavy-ion collisions.

首次测量已识别带电强子的所有组合的平衡函数 (BF)$(\pi ,\mathrm{ķ},\mathrm{p})$Pb-Pb 碰撞中的对$\sqrt{s_{{}_{\mathrm{神经网络}}}}=2.76$呈现由 ALICE 探测器记录的 TeV。BF 测量作为二维微分相关器与强子对的相对速度 (Δ y ) 和方位角 (Δ φ ) 进行比较，并作为碰撞中心性的函数进行研究。BF的 Δ φ依赖性预计对夸克 - 胶子等离子体中的轻夸克扩散率敏感。虽然所有对的 BF 方位角宽度从外围到中心碰撞显着减小，但纵向宽度表现出混​​合行为： BFs of ππ在更中心的碰撞中，跨物种对显着缩小，而发现 KK 和 pp 的对与碰撞中心性无关。这种二分法在质量上与强径向流效应的存在和相对论重离子碰撞中夸克产生的两个阶段的存在一致。最后，提出了 BF 积分的碰撞中心性演化的第一次测量，观察到电荷平衡分数几乎与 Pb-Pb 碰撞中的碰撞中心性无关。总体而言，所提出的结果为相对论重离子碰撞中强子产生和传输的理论模型提供了新的和具有挑战性的约束。