NA61/SHINE实验关于带电和中性强子产生的新结果
News on charged and neutral hadron production from NA61/SHINE
浏览论文内容
中文总结 AI 辅助
NA61/SHINE实验分析SPS能区中等核碰撞的强子产生数据，揭示K介子比值的系统尺寸依赖、重子输运特性及同位旋对称性破缺的潜在迹象。
中文摘要 AI 辅助
高能强子与核碰撞中的奇异粒子产生，仍是极端条件下强相互作用物质研究的核心课题。欧洲核子研究中心（CERN）超级质子同步加速器（SPS）上的NA61/SHINE实验采集的数据，可对不同碰撞能量与系统尺寸下的强子产生进行全面扫描。本文聚焦于SPS能区中等尺寸核（如Ar+Sc、Xe+La）中心碰撞中带电与中性强子产生的新结果：首先讨论K⁺/π⁺比值的能量与系统尺寸依赖关系，确认中心Pb+Pb碰撞中存在“ horn”结构，而较小系统中无此结构；还分析了K介子横质量（横动量）谱的逆斜率参数T，显示中等尺寸系统的T值与中心Pb+Pb碰撞中的观测值相当。其次给出中心Be+Be、Ar+Sc、Pb+Pb碰撞中归一化质子快度谱（dn/dy）/⟨W⟩，证明重子输运随能量与系统尺寸变化的依赖关系。在此基线之上，探究SPS能区中心Ar+Sc碰撞中Λ超子的产生，将其快度谱、平均多重数⟨Λ⟩及与π介子的比值，与模型预测和现有数据对比。最后报道中心Ar+Sc碰撞中带电K介子相对中性K介子出现反常过量（R_K > 1），凸显同位旋对称性可能存在的意外大尺度破缺。
英文摘要
Strangeness production in high-energy hadronic and nuclear collisions remains a central topic in the study of strongly interacting matter under extreme conditions. The data collected by the NA61/SHINE experiment at the CERN SPS allow for a comprehensive scan of hadron production across various collision energies and system sizes. This article focuses on new results on charged and neutral hadron production in central collisions of medium-sized nuclei, such as Ar+Sc and Xe+La, in the SPS energy range. First, the energy and system-size dependence of the $K^+/π^+$ ratio is discussed, confirming the ``horn'' structure in central Pb+Pb collisions and its absence in smaller systems. Furthermore, the inverse slope parameter $T$ of kaon transverse mass (transverse momentum) spectra is analyzed, showing that intermediate-size systems reach values comparable to those observed in central Pb+Pb collisions. Second, normalized proton rapidity spectra $(\text{d}n/\text{d}y)/\langle W \rangle$ in central Be+Be, Ar+Sc, and Pb+Pb collisions are presented, demonstrating energy-dependent baryon transport as a function of system size. Building on this baseline, $Λ$ hyperon production in central Ar+Sc collisions is explored across SPS energies, where rapidity spectra, mean multiplicities ($\langle Λ\rangle$), and ratios to pions are compared with model predictions and existing data. Finally, an anomalous excess of charged over neutral kaons ($R_K > 1$) in central Ar+Sc collisions is reported, highlighting a potential unexpectedly large violation of isospin symmetry.
