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arXiv 2602.08534hep-phhep-ex
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LHC Run 3能量下pp、O-O和Pb-Pb碰撞中全局可观测量和识别强子产率

Global observables and identified-hadron production in pp, O-O and Pb-Pb collisions at LHC Run 3 energies with EPOS4

Nuclear and Particle Physics Research Centre, Department of Physics, Jadavpur University（贾达普大学物理系核与粒子物理研究中心）；School of Studies in Environmental Radiation and Archaeological Sciences, Jadavpur University（贾达普大学环境辐射与考古科学学院）

Hirak Kumar Koley, Mitali Mondal

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34 pages, 21 figures
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AI总结：

EPOS4模型研究了LHC Run 3能量下pp、O-O和Pb-Pb碰撞中全局可观测量和识别强子产率，揭示了非普遍的⟨p_T⟩标度、强子相效应及系统尺寸依赖的R_AA抑制。

摘要：

小规模和大规模碰撞系统中集体性的观测挑战了我们对热化和粒子产生机制的理解。EPOS4通过动态的核心-冠层分离模型来模拟这一过程，其中高密度区域形成集体扩展的核心，而低密度区域通过弦碎裂进行强子化。其微canonical核心强子化改进了横动量和乘积依赖性可观测量的描述。我们给出了EPOS4对pp、O-O和Pb-Pb碰撞的预测，包括有无UrQMD的情况，展示了非普遍的⟨p_T⟩标度、显著的强子相效应以及系统尺寸依赖的R_AA抑制。带电粒子和横能密度显示参与者标度；在相同参与者分数下，O-O系统的横能每带电粒子系统性更大，表明在较轻系统中有效生产更硬。识别强子谱随着事件多重性增加而变硬，具有质量顺序和增加的核心分数。平均横动量表现出强烈的系统依赖性，pp系统中多重性演化最陡，表明⟨p_T⟩不遵循普遍的多重性标度。p/π比在中间p_T区域增强；在最高Pb-Pb多重性下，积分p/π的抑制仅在UrQMD中得到再现，突显了强子相效应。核修改因子在Pb-Pb中显示出显著的抑制，在中心O-O碰撞中显示出实质性的抑制。爆波拟合显示出T_kin和⟨β_T⟩之间的反相关性，UrQMD将参数向较低的T_kin和较高的⟨β_T⟩方向移动。这些结果为Run~3测量提供了及时的基础，并用于约束介质效应在系统尺寸上的起始点。

英文摘要：

The observation of collectivity in small and large collision systems challenges our understanding of thermalization and particle production. EPOS4 models this via a dynamical core--corona separation, where high-density regions form a collectively expanding core while low-density regions hadronize via string fragmentation. Its microcanonical core hadronization improves the description of transverse momentum and multiplicity-dependent observables. We present EPOS4 predictions for pp, O-O and Pb-Pb collisions, with and without UrQMD, showing non-universal $\langle p_T\rangle$ scaling, significant hadronic-phase effects, and system-size-dependent $R_{AA}$ suppression. Charged-particle and transverse-energy densities show participant scaling; the transverse energy per charged particle is systematically larger in O--O than in Pb--Pb at comparable participant fraction, indicating a harder effective production in the lighter system. Identified-hadron spectra harden with event multiplicity with mass ordering and increasing core fractions. The mean transverse momentum exhibits a strong system dependence, with the steepest multiplicity evolution in pp, demonstrating that $\langle p_T\rangle$ does not follow universal multiplicity scaling. The $p/π$ ratio shows an enhanced intermediate-$p_T$ region; the suppression of the integrated $p/π$ at the highest Pb--Pb multiplicities is reproduced only with UrQMD, highlighting hadronic-phase effects. The nuclear modification factor shows sizeable suppression in Pb--Pb and substantial suppression in central O--O collisions. Blast-wave fits exhibit the anti-correlation between $T_{\rm kin}$ and $\langleβ_T\rangle$, with UrQMD shifting the parameters towards lower $T_{\rm kin}$ and higher $\langleβ_T\rangle$. These results provide a timely baseline for Run~3 measurements and for constraining the onset of medium-like effects across system size.

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