质心系能量√s_NN=200 GeV下Zr+Zr与Ru+Ru碰撞中中子皮参数的提取
Extraction of Neutron-Skin Parameters in Zr+Zr and Ru+Ru Collisions at $\sqrt{s_{\text{NN}}}$ = 200 GeV
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中文总结 AI 辅助
本研究基于UrQMD模型，通过χ²分析STAR实验数据，提取同量异位素碰撞的中子皮参数差，明确中子皮效应影响重子输运比，为探索QCD现象提供初态几何约束的重要性。
中文摘要 AI 辅助
碰撞原子核的初始核几何（体现为质子与中子密度分布）是决定高能重离子碰撞末态效应的关键因素。本研究在UrQMD模型中引入同位旋依赖的Woods-Saxon分布以考虑中子皮效应，针对质心系能量√s_NN=200 GeV下的⁹⁶Ru+⁹⁶Ru与⁹⁶Zr+⁹⁶Zr碰撞开展研究。通过系统扫描⁹⁶Zr核的质子表面弥散参数a_p,Zr，并与STAR实验数据进行χ²分析，利用净电荷产额差ΔQ，提取得到这两个同量异位素系统间的相对中子皮厚度差为0.278±0.018 fm。研究进一步表明，中子皮效应会显著改变重子-电荷输运比R_{B/Q}=⟨B⟩/ΔQ × ΔZ/A，且对中心碰撞中观测到的R_{B/Q}>1行为产生重要影响。本工作指出，核结构效应对重子输运可观测量的贡献不可忽略，且无需引入重子结假说，同时强调了精确初态几何约束对探索相对论重离子碰撞中新型QCD现象的重要性。
英文摘要
The initial nuclear geometry of colliding nuclei, manifested in proton and neutron density profiles, plays a key role in determining final-state effects in high-energy heavy-ion collisions. We study ${^{96}\text{Ru}}+{^{96}\text{Ru}}$ and ${^{96}\text{Zr}}+{^{96}\text{Zr}}$ collisions at $\sqrt{s_{\text{NN}}}=200$ GeV incorporating an isospin-dependent Woods-Saxon distribution to account for neutron-skin effects in the UrQMD model. By systematically scanning the proton surface diffuseness parameter $a_{\text{p,Zr}}$ of the $^{96}\text{Zr}$ nucleus and performing a $χ^2$ analysis by comparing with STAR experimental data, we extract the relative neutron-skin thickness difference $0.278 \pm 0.018$ fm between the two isobaric systems using the net-charge yield difference $ΔQ$. We further show that the neutron-skin effect evidently modifies the baryon-to-charge transport ratio $R_{B/Q}=\langle B \rangle/ΔQ \times ΔZ/A$, and substantially influences the observed $R_{B/Q}>1$ behavior in central collisions. This work indicates that nuclear structure effects contribute non-negligibly to baryon transport observables without a baryon junction hypothesis, and underscores the importance of precise initial-state geometry constraints for exploring novel QCD phenomena in relativistic heavy-ion collisions.
