比较EPOS-4、EPOS-LHC和SMASH在NICA能量范围内的识别强子观测量
Comparing EPOS-4, EPOS-LHC, and SMASH for identified-hadron observables in the NICA energy range
AI总结：
研究比较EPOS-4、EPOS-LHC和SMASH在Au+Au碰撞中强子产生观测量，分析不同模型在中子产额、横向动量谱及 strangeness 生产中的差异，揭示模型间在不同能量下的表现差异。
摘要：
我们系统地模拟了最小偏置Au+Au碰撞中识别强子的产生，能量范围为sqrt(sNN)=6、7和8 GeV。事件样本由三种基于不同微观图景的现代框架生成：EPOS-LHC、EPOS-4和纯色子传输模型SMASH。我们比较了探测重子停止、横向动力学、强子形成和strangeness生产的观测量：速率密度dN/dy、横向动量谱dN/dpT、二维pT-y分布、v2/nq与pT/nq以及产额比pi-/pi+、K-/K+、pbar/p、K+/pi+、K-/pi-、p/pi+和Lambda/pi+。对于带电和中性π子，三种模型在dN/dy和dN/dpT中给出相似的产额和谱形。在这些能量下，共振衰变和异ospin约束降低了对早期阶段动力学的敏感性。相反，奇异介子和重子仍强烈依赖于模型。EPOS-4给出中快速度K+和Lambda最大的产额和最硬的K和奇异重子pT谱。EPOS-LHC总体上处于中间位置，而SMASH给出较低的奇异强子产额。二维pT-y图显示EPOS模型在更宽的快速度范围内填充更高的pT。对于NCQ缩放的椭圆流，EPOS-LHC显示出最佳的近似缩放，而SMASH和EPOS-4仅显示部分缩放。这表明在该能量范围内，EPOS-LHC在有核子阶段携带了更连贯的夸克-胶子等离子体各向异性。总体而言，模型分离从6到8 GeV逐渐增加。在NICA领域，最清晰的判别因子是中间pT重子到介子比、Lambda/pi+、pT的快速度依赖性、K-/K+的pT依赖性以及NCQ缩放的v2。
英文摘要：
We present a systematic simulation study of identified hadron production in minimum bias Au+Au collisions at sqrt(sNN) = 6, 7, and 8 GeV. The event samples were generated with three modern frameworks based on different microscopic pictures: EPOS-LHC, EPOS-4, and the purely hadronic transport model SMASH. We compare observables that probe baryon stopping, transverse dynamics, hadron formation, and strangeness production: rapidity densities dN/dy, transverse momentum spectra dN/dpT, two dimensional pT-y distributions, v2/nq versus pT/nq, and the yield ratios pi-/pi+, K-/K+, pbar/p, K+/pi+, K-/pi-, p/pi+, and Lambda/pi+. For charged and neutral pions, the three models give broadly similar yields and spectral shapes in both dN/dy and dN/dpT. At these energies, resonance decays and isospin constraints reduce the sensitivity to early stage dynamics. In contrast, strange mesons and baryons remain strongly model dependent. EPOS-4 gives the largest midrapidity K+ and Lambda yields and the hardest kaon and strange baryon pT spectra. EPOS-LHC is generally intermediate, while SMASH gives lower strange hadron production. The two dimensional pT-y maps show that the EPOS models populate higher pT over a broader rapidity range. For NCQ scaled elliptic flow, the best approximate scaling is seen in EPOS-LHC, while SMASH and EPOS-4 show only partial scaling. This suggests that EPOS-LHC carries a more coherent partonic anisotropy to the hadronic stage in this energy range. Overall, the model separation grows from 6 to 8 GeV. The clearest discriminators in the NICA domain are intermediate pT baryon to meson ratios, Lambda/pi+, the rapidity dependence of pT, the pT dependence of K-/K+, and NCQ scaled v2.
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