核物质中声速的上限：输运计算与微扰量子色动力学约束的协同作用
Upper Limit of Sound Speed in Nuclear Matter: A Harmonious Interplay of Transport Calculation and Perturbative Quantum Chromodynamic Constraint
AI总结：
本研究通过重构基于多信使观测的中子星状态方程，验证了核物质声速上限 $c_{\rm s}^2 \leq 0.781$，并证明该输运计算约束与 pQCD 边界高度一致，为两者的有效性提供了强力支持。
摘要：
最近有研究表明，通过输运计算可以得出核物质中平方声速的上限，即 $c_{\rm s}^2 \leq 0.781$。在本研究中，我们证明这一上限得到了超密物质重构状态方程（EOS；采用非参数方法建模）的印证。该重构整合了中子星的多信使观测数据，特别是采用了 NICER 对 PSR J0437-4715（$11.36^{+0.95}_{-0.63}$ km）、PSR J0030+0451（在 ST+PDT 模型下为 $11.71^{+0.88}_{-0.83}$ km）以及 PSR J0740+6620（$12.49^{+1.28}_{-0.88}$ km）的最新半径测量结果。结果表明，在所有情况下，EOS 的 $c_{\rm s}^2 \leq 0.781$ 上限自然会使大质量中子星中心附近的物质性质与来自 pQCD 的因果驱动约束保持一致；在实践中，应用 pQCD 似然的密度（$n_{\rm L}$）设定在 $10n_s$（其中 $n_s$ 为核饱和密度）。我们还注意到，最大 $c_s^2$ 与 $n_{\rm L}$ 之间存在强相关性，且当 $n_{\rm L} = n_{\rm c,TOV}$ 时，$c_{\rm s}^2 \leq 0.781$ 在某种程度上会被违反。该结果表明，即使考虑到统计上的不确定性，更高的 $n_{\rm L}$ 也是更自然的。此外，从这两个截然不同且独立的约束（即输运计算和 pQCD 边界）得出的结果之间的高度一致性，为它们的有效性提供了强有力的支持。另外，$R_{1.4}$、$R_{2.0}$、$R_{1.4}-R_{2.0}$ 和 $M_{\rm TOV}$ 的最新联合约束分别为 $11.94_{-0.68}^{+0.77}$ km、$11.99_{-0.67}^{+0.88}$ km、$-0.1_{-0.27}^{+0.42}$ km 和 $2.24_{-0.10}^{+0.13}M_\odot$（在 $90\\%$ 的置信水平下）。
英文摘要：
Very recently, it has been shown that there is an upper bound on the squared sound speed of nuclear matter from the transport, which reads $c_{\rm s}^2 \leq 0.781$. In this work, we demonstrate that this upper bound is corroborated by the reconstructed equation of state (EOS; modeled with a nonparametric method) for ultradense matter. The reconstruction integrates multimessenger observation for neutron stars, in particular, the latest radius measurements for PSR J0437-4715 ($11.36^{+0.95}_{-0.63}$ km), PSR J0030+0451 ($11.71^{+0.88}_{-0.83}$ km, in the ST+PDT model), and PSR J0740+6620 ($12.49^{+1.28}_{-0.88}$ km) by NICER have been adopted. The result shows in all cases, the $c_{\rm s}^2 \leq 0.781$ upper limit for EOS will naturally yield the properties of matter near the center of the massive neutron star consistent with the causality-driven constraint from pQCD, where, in practice, the density in implementing the pQCD likelihood ($n_{\rm L}$) is applied at $10n_s$ (where $n_s$ is the nuclear saturation density). We also note that there is a strong correlation for the maximum $c_s^2$ with $n_{\rm L}$, and $c_{\rm s}^2 \leq 0.781$ is somehow violated when $n_{\rm L} = n_{\rm c,TOV}$. The result indicates that a higher $n_{\rm L}$, even considering the uncertainties from statistics, is more natural. Moreover, the remarkable agreement between the outcomes derived from these two distinct and independent constraints (i.e., the transport calculation and pQCD boundary) lends strong support to their validity. In addition, the latest joint constraint for $R_{1.4}$, $R_{2.0}$, $R_{1.4}-R_{2.0}$, and $M_{\rm TOV}$ are $11.94_{-0.68}^{+0.77}$ km, $11.99_{-0.67}^{+0.88}$ km, $-0.1_{-0.27}^{+0.42}$ km, and $2.24_{-0.10}^{+0.13}M_\odot$ (at $90\%$ credible level), respectively.
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。
