"Table 113" of "Anisotropic flow and flow fluctuations of identified hadrons in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV"

The first measurements of elliptic flow of $\mathrm{\pi}^{\pm}$, $\mathrm{K}^{\pm}$, $\mathrm{p}+\bar{\mathrm{p}}$, $\mathrm{K_{S}^{0}}$, $\Lambda+\bar{\Lambda}$, $\mathrm{\phi}$, $\mathrm{\Xi^{\mp}}$, and $\mathrm{\Omega^{\mp}}$ using multiparticle cumulants in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV are presented. Results obtained with two- ($v_2\{2\}$) and four-particle cumulants ($v_2\{4\}$) are shown as a function of transverse momentum, $p_{\rm T}$, for various collision centrality intervals. Combining the data for both $v_2\{2\}$ and $v_2\{4\}$ also allows us to report the first measurements of the mean elliptic flow, elliptic flow fluctuations, and relative elliptic flow fluctuations for various hadron species. These observables probe the event-by-event eccentricity fluctuations in the initial state and the contributions from the dynamic evolution of the expanding quark--gluon plasma. The characteristic features observed in previous $p_{\rm T}$-differential anisotropic flow measurements for identified hadrons with two-particle correlations, namely the mass ordering at low $p_{\rm T}$ and the approximate scaling with the number of constituent quarks at intermediate $p_{\rm T}$, are similarly present in the four-particle correlations and the combinations of $v_2\{2\}$ and $v_2\{4\}$. In addition, a particle species dependence of flow fluctuations is observed that could indicate a significant contribution from final state hadronic interactions. The comparison between experimental measurements and CoLBT model calculations, which combine the various physics processes of hydrodynamics, quark coalescence, and jet fragmentation, illustrates their importance over a wide $p_{\rm T}$ range.

本文报道了在质心系能量√s_NN=5.02 TeV的铅-铅（Pb--Pb）碰撞中，利用多粒子累积量（multiparticle cumulants）对π±、K±、p+$ar{p}$、K_S^0、Λ+$ar{Λ}$、φ、Ξ∓和Ω∓的椭圆流（elliptic flow）开展的首次测量。研究给出了两粒子累积量（two-particle cumulants）v₂{2}与四粒子累积量（four-particle cumulants）v₂{4}的结果，二者均作为横向动量（transverse momentum, $p_{
m T}$）的函数，对应不同的碰撞中心度区间。通过联合分析v₂{2}与v₂{4}的实验数据，我们还首次报道了不同强子种类的平均椭圆流、椭圆流涨落（elliptic flow fluctuations）以及相对椭圆流涨落的测量结果。这些观测量可用于探究初始态的逐事件偏心率涨落（event-by-event eccentricity fluctuations），以及膨胀夸克胶子等离子体（quark--gluon plasma）的动力学演化贡献。此前通过两粒子关联开展的识别强子$p_{
m T}$微分各向异性流（anisotropic flow）测量中所观测到的典型特征——即低$p_{
m T}$区间的质量分级，与中间$p_{
m T}$区间随组分夸克数近似标度的行为——在四粒子关联以及v₂{2}与v₂{4}的联合分析中同样存在。此外，本研究还观测到流涨落存在强子种类依赖性，这一现象暗示末态强相互作用（final state hadronic interactions）可能存在显著贡献。将实验测量结果与结合了流体力学（hydrodynamics）、夸克聚合（quark coalescence）与喷注碎裂（jet fragmentation）多种物理过程的CoLBT模型计算结果进行对比，可说明该模型在宽广$p_{
m T}$区间内的物理意义。