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arXiv 2603.07597nucl-thnucl-ex
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利用LHC重离子碰撞中的各向异性流约束$^{208}$Pb的中子皮

Sensitivity of anisotropic flow in Pb+Pb collisions to the neutron skin of $^{208}$Pb at energies available at the CERN Large Hadron Collider

University of Shanghai for Science and Technology(上海理工大学);Institute of Modern Physics, Fudan University(复旦大学现代物理研究所);Shanghai Research Center for Theoretical Nuclear Physics, NSFC and Fudan University(国家自然科学基金委与复旦大学理论核物理上海研究中心)

Xin-Li Zhao, Xin-Yi Xie, Yuan Li, Guo-Liang Ma

AI总结:

通过LHC Pb+Pb碰撞中的各向异性流研究,约束$^{208}$Pb的中子皮效应,发现中子皮大小对流测量的敏感性和局限性。

摘要:

我们利用改进的多相传输模型的字符串熔化版本,通过改变中子密度分布,研究了在$\sqrt{s_{\mathrm{NN}}}=5.02$~TeV的Pb+Pb碰撞中$^{208}$Pb的中子皮效应。在初始不均匀性和各向异性流中观察到系统响应,表明中子皮效应在重离子碰撞的完整传输演变中得以保留。与ALICE数据的$χ^2$比较支持较小到中等的中子皮,而大中子皮被排除。零和中等中子皮提供的相似描述表明,在当前的Pb+Pb碰撞中的各向异性流中存在几何退化性,其中各向异性流主要由整体碰撞几何形状和大小驱动,因此缺乏对核表面轮廓细节数的极端敏感性。这突显了在LHC的Pb+Pb碰撞中通过流测量约束中子皮性质的敏感性和局限性。

英文摘要:

We study the sensitivity of anisotropic flow in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$~TeV to the neutron skin of $^{208}$Pb using the improved string-melting version of a multiphase transport (AMPT) model. By varying the neutron surface diffuseness, we trace the impact of several neutron-skin scenarios from the initial nuclear density profiles and eccentricities to final-state charged-particle production and flow cumulants. A systematic response is observed in both the initial eccentricities and the anisotropic flow, indicating that the neutron-skin-induced geometric effects can survive the full transport evolution. A model-to-data comparison with ALICE measurements disfavors the most compact and most diffuse density profiles within the tested AMPT setup, while the reference and moderate-skin configurations give comparable descriptions. Their similarity reflects a geometric degeneracy in large Pb+Pb collision systems, where the inclusive anisotropic flow is dominated by the effective collision geometry and nuclear size, making it only weakly sensitive to the detailed structure of the neutron surface. These results clarify both the sensitivity and the limitations of using anisotropic flow in relativistic heavy-ion collisions to probe neutron-skin effects.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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