The shape phase transition for certain isotope or isotone chains, associated with the quantum phase transition of finite nuclei, is an intriguing phenomenon in nuclear physics. A notable case is the Xe isotope chain, where the structure transits from a 𝛾-soft rotor to a spherical vibrator, with the second-order shape phase transition occurring in the vicinity of 128–130Xe. In this Letter, we focus on investigating the 𝛾-soft deformation of 129Xe associated with the second-order shape phase transition by constructing novel correlators for ultrarelativistic 129Xe+129Xe collisions. In particular, our iEBE-VISHNU model calculations show that the correlation between elliptic flow 𝑣2 and mean transverse momentum [𝑝𝑇], denoted as 𝜌2, as well as the [𝑝𝑇] fluctuation Γ𝑝𝑇, which were previously used to claim the evidence of the rigid triaxial deformation of 129Xe, can also be well explained by the 𝛾-soft deformation of 129Xe. We further propose two novel correlators 𝜌4,2 and 𝜌2,4, which carry nontrivial higher-order correlations and show unique capabilities to distinguish between the 𝛾-soft and the rigid triaxial deformation of 129Xe in 129Xe+129Xe collisions at the LHC. The present study provides a novel way to explore the second-order shape phase transition of finite nuclei with ultrarelativistic heavy ion collisions.

中文翻译：

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探索 LHC 超相对论性 Xe129+Xe129 碰撞中的核形相变


某些同位素或同位素链的形状相变与有限原子核的量子相变有关，是核物理学中一个有趣的现象。一个值得注意的例子是 Xe 同位素链，其中结构从γ软转子过渡到球形可控震源，二阶形状相变发生在 128-130Xe 附近。在这封信中，我们通过构建超相对论 129Xe+129Xe 碰撞的新型相关器，专注于研究 129Xe 与二阶形状相变相关的 129Xe 的γ软变形。特别是，我们的 iEBE-VISHNU 模型计算表明，椭圆流 v2 与平均横向动量 [pT] 之间的相关性，表示为 ρ2，以及 [pT] 波动 ΓpT，这些以前用于声称 129Xe 刚性三轴变形的证据，也可以用 129Xe 的γ软变形很好地解释。我们进一步提出了两个新的相关器 ρ42 和 ρ24，它们具有非平凡的高阶相关性，并显示出在 LHC 的 129Xe+129Xe 碰撞中区分 129Xe 的γ软和刚性三轴变形的独特能力。本研究为探索具有超相对论重离子碰撞的有限核的二阶形状相变提供了一种新方法。