标题： PbAu 碰撞中$v^{1/3}_{3}/v^{1/2}_{2}$比率在$\sqrt{s_{\mathrm{NN}}} = $17.3 GeV：流体力学行为的暗示 显示英文标题

标题： The $v^{1/3}_{3}/v^{1/2}_{2}$ ratio in PbAu collisions at $\sqrt{s_{\mathrm{NN}}} = $ 17.3 GeV: a hint of a hydrodynamic behavior

摘要： 负π介子的傅里叶谐波，$v_2$和$v_3$在每核子对质心能量$\sqrt{s_{\mathrm{NN}}}$= 17.3 GeV 的中 rapidity 区域由 CERES/NA45 实验在 CERN SPS 的 0--30% 中心 PbAu 碰撞中测量，平均中心性为 5.5%。 分析是按横动量$\mathrm{p_{\mathrm{T}}}$从 0.05 GeV/$c$到超过 2 GeV/$c$的两个中心性区间进行的。 这是首次在 SPS 能量下测量$v^{1/3}_{3}/v^{1/2}_{2}$比率随横动量的变化，该测量独立于流体力学模型，揭示了形成系统的流体动力学行为。 对于高于0.5 GeV/$c$的$\mathrm{p_{\mathrm{T}}}$，该比值几乎平坦，与流体动力学预测一致，并且与ATLAS和ALICE实验在更高LHC能量下之前观察到的结果一致。 结果还与SMASH-vHLLE混合模型的预测以及单独应用的SMASH模型进行了比较。 显示英文摘要

摘要： The Fourier harmonics, $v_2$ and $v_3$ of negative pions are measured at center-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}$= 17.3 GeV around midrapidity by the CERES/NA45 experiment at the CERN SPS in 0--30\% central PbAu collisions with a mean centrality of 5.5\%. The analysis is performed in two centrality bins as a function of the transverse momentum $\mathrm{p_{\mathrm{T}}}$ from 0.05 GeV/$c$ to more than 2 GeV/$c$. This is the first measurement of the $v^{1/3}_{3}/v^{1/2}_{2}$ ratio as a function of transverse momentum at SPS energies, that reveals, independently of the hydrodynamic models, hydrodynamic behavior of the formed system. For $\mathrm{p_{\mathrm{T}}}$ above 0.5 GeV/$c$, the ratio is nearly flat in accordance with the hydrodynamic prediction and as previously observed by the ATLAS and ALICE experiments at the much higher LHC energies. The results are also compared with the SMASH-vHLLE hybrid model predictions, as well as with the SMASH model applied alone.