Nuclei having 4n number of nucleons are theorized to possess clusters of α particles (4He nucleus). The Oxygen nucleus (16O) is a doubly magic nucleus, where the presence of an α-clustered nuclear structure grants additional nuclear stability. In this study, we exploit the anisotropic flow coefficients to discern the effects of an α-clustered nuclear geometry with respect to a Woods-Saxon nuclear distribution in O–O collisions at sNN=7 TeV using a hybrid of IP-Glasma + MUSIC + iSS + UrQMD models. In addition, we use the multi-particle cumulants method to measure anisotropic flow coefficients, such as elliptic flow (v2) and triangular flow (v3), as a function of multiplicity class. Anisotropic flow fluctuations, which are expected to be larger in small collision systems, are also studied for the first time in O–O collisions. It is found that an α-clustered nuclear distribution gives rise to an enhanced value of v2 and v3 for the low-multiplicity events. Consequently, a rise in v3/v2 is also observed for the 0–10% multiplicity class. Further, for α-clustered O–O collisions, fluctuations of v2 are larger for the highest multiplicity events, which decrease as the final-state multiplicity decreases. In contrast, for a Woods-Saxon 16O nucleus, v2 fluctuations show an opposite behavior with decreasing multiplicity. When confronted with experimental data, this study may reveal the importance of the nuclear density profile on the discussed observables and provide physics validation for the hybrid model discussed in this work.

中文翻译：

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各向异性流动涨落是大型强子对撞机的 O-O 碰撞中成簇核几何的可能特征


理论上，具有 4n 个核子的原子核具有 α 粒子簇（4He 原子核）。氧原子核 （16O） 是一个双重神奇的原子核，其中α簇核结构的存在提供了额外的核稳定性。在这项研究中，我们利用各向异性流动系数来辨别α簇核几何结构对 sNN=7 TeV 时 O-O 碰撞中伍兹-撒克逊核分布的影响，使用 IP-Glasma + MUSIC + iSS + UrQMD 模型的混合。此外，我们使用多粒子累积量方法来测量各向异性流动系数，例如椭圆流 （v2） 和三角流 （v3），作为多重性类的函数。各向异性流动波动（预计在小型碰撞系统中会更大）也首次在 O-O 碰撞中进行了研究。研究发现，对于低复数事件，α簇核分布产生了 v2 和 v3 的增强值。因此，对于 0-10% 的多重性类，也观察到 v3/v2 的增加。此外，对于α簇的 O-O 碰撞，对于最高多重性事件，v2 的波动更大，随着最终状态多重性的降低而减小。相比之下，对于 Woods-Saxon 16O 原子核，v2 波动表现出与多重性减小相反的行为。当面对实验数据时，这项研究可能会揭示核密度分布对所讨论的可观察对象的重要性，并为本研究中讨论的混合模型提供物理验证。