发表机构
Nanjing University; Hangzhou Institute for Advanced Study, UCAS（南京大学; 中国科学院大学杭州高等研究院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过构建密度分辨的核子参考域，证明中子星热力学特征（多方指数与声速）不能唯一标识退紧闭相变，并定量表明现有观测未拒绝核子零假设。
AI 中文摘要
中子星物质中多方指数 $\Gamma_\varepsilon \lesssim 1.75$ 的微小性和声速 $c_s^2 \approx 1/3$ 的近共形性通常被认为是夸克物质出现的信号。我们利用由核物质性质以及中子星质量、半径和潮汐数据共同约束的核子状态方程（EoS），在 $(P/P_{\rm free},\Gamma_\varepsilon)$ 平面上构建了一个密度分辨的核子参考域，并发现该域明确延伸至 $\Gamma_\varepsilon=1.75$ 以下。至关重要的是，核子域仅在包含 $Z_0$ 和 $Z_{sym}$ 后才对截断阶数保持稳定，这表明高阶密度依赖性控制着从有限核到中子星物质的外推。因此，这些发现为有限核和重离子实验提供了具体目标，同时将地面核物理与多信使观测直接联系起来。我们将该域与由神经网络生成的无相标签、并通过符号回归表示的平滑状态方程进行比较。在这些重构中，$35.29\\%$ 的完整轨迹在 $0.5\leq n/n_0\leq8$ 范围内位于核子域内。在最小化多信使损失后获得的EoS样本中，$\max_n c_s^2(n)$ 的最小值为0.38，高于共形值 $1/3$。总之，我们将微观解释转化为一个可证伪的、密度分辨的零假设检验，并定量表明当前观测在状态方程的很大可允许空间内并未拒绝核子零假设。
英文摘要
The smallness of polytropic index $Γ_\varepsilon \lesssim 1.75$ and near conformality of sound velocity $c_s^2 \approx 1/3$ in neutron star matter are usually referred to as signals of the emergence of quark matter. We construct a density-resolved nucleonic reference domain in the \((P/P_{\rm free},Γ_\varepsilon)\) plane using nucleonic EoSs jointly constrained by nuclear matter properties and neutron star mass, radius and tidal data, and found that the domain extends unambiguously below \(Γ_\varepsilon=1.75\). Crucially, the nucleonic domain becomes stable against the truncation order only after \(Z_0\) and \(Z_{sym}\) are included, showing that the higher-order density dependence controls the extrapolation from finite nuclei to neutron-star matter. These findings therefore provide concrete targets for finite-nucleus and heavy-ion experiments, while linking terrestrial nuclear physics directly to multimessenger observations. We compare the domain with smooth equations of state generated by neural networks without phase labels and represented by symbolic regression. Among these reconstructions, \(35.29\%\) have complete trajectories inside the nucleonic domain over \(0.5\leq n/n_0\leq8\). Within the EoS sample obtained after minimizing the multimessenger loss, the smallest value of \(\max_n c_s^2(n)\) is 0.38, above the conformal value $1/3$. In conclusion, we convert microscopic interpretation into a falsifiable, density-resolved null-hypothesis test and show quantitatively that current observations do not reject the nucleonic null over much of the admissible space of equation of state.
