[论文解读] Dense Nuclear Matter Equation of State from Heavy-Ion Collisions

Agnieszka Sorensen, Kshitij Agarwal+134 more|arXiv (Cornell University)|Jan 30, 2023

High-Energy Particle Collisions Research被引用 9

一句话总结

本文认为重离子碰撞和强子输运模拟对于在广泛的密度和温度范围内约束致密核物质方程状态的状态方程是必不可少的，强调机遇、挑战，以及建立协同理论计划的必要性。

ABSTRACT

The nuclear equation of state (EOS) is at the center of numerous theoretical and experimental efforts in nuclear physics. With advances in microscopic theories for nuclear interactions, the availability of experiments probing nuclear matter under conditions not reached before, endeavors to develop sophisticated and reliable transport simulations to interpret these experiments, and the advent of multi-messenger astronomy, the next decade will bring new opportunities for determining the nuclear matter EOS, elucidating its dependence on density, temperature, and isospin asymmetry. Among controlled terrestrial experiments, collisions of heavy nuclei at intermediate beam energies (from a few tens of MeV/nucleon to about 25 GeV/nucleon in the fixed-target frame) probe the widest ranges of baryon density and temperature, enabling studies of nuclear matter from a few tenths to about 5 times the nuclear saturation density and for temperatures from a few to well above a hundred MeV, respectively. Collisions of neutron-rich isotopes further bring the opportunity to probe effects due to the isospin asymmetry. However, capitalizing on the enormous scientific effort aimed at uncovering the dense nuclear matter EOS, both at RHIC and at FRIB as well as at other international facilities, depends on the continued development of state-of-the-art hadronic transport simulations. This white paper highlights the essential role that heavy-ion collision experiments and hadronic transport simulations play in understanding strong interactions in dense nuclear matter, with an emphasis on how these efforts can be used together with microscopic approaches and neutron star studies to uncover the nuclear EOS.

研究动机与目标

• 激发并概述重离子碰撞如何在密度范围（0.3–5 n0）和温度范围内探测致密核物质的方程状态。
• 阐明强子输运模拟在解释碰撞观测量和约束EOS中的作用。
• 讨论重离子结果、微观理论（例如手性有效场理论 χEFT）与中子星研究之间的联系。
• 确定未来十年推进EOS测定的机遇与科学需求。

提出的方法

• 描述输运理论，以及如何使用强子输运模型从重离子碰撞数据中提取EOS约束。
• 总结从碰撞获得的对称和非对称（同位旋相关）EOS 的若干约束。
• 讨论与微观计算（如 χEFT）和中子星约束的整合，以形成一个连贯的EOS图景。
• 倡导贝叶斯推断和不确定性量化，以整合多样化的数据集。

Figure 1.1: Schematic depiction of the ranges of density and temperature probed in experiments and astronomical observations sensitive to the EOS of nuclear matter ( counterclockwise from bottom left ): neutron star (NS) crust physics, including nuclear pasta structures; properties of nuclei; struct

实验结果

研究问题

• RQ1 中等能量范围的重离子碰撞可以达到的重子密度和温度范围是什么，观测量如何在这些范围内约束EOS？
• RQ2 如何对强子输运模拟进行稳健的验证，并用于从数据中提取对称物质EOS和对称能信息？
• RQ3 富中子系统和同位旋不对称性在约束高密度下EOS的密度依赖性和对称能方面的作用是什么？

主要发现

• 重离子碰撞探测到的重子密度从几分之一到大约5倍n0，温度从几MeV到远高于100 MeV。
• 输运模型的鲁棒性和不确定性量化对于从碰撞数据得到可靠的EOS约束至关重要。
• 贝叶斯分析通过结合多样化的测量并量化不确定性来约束EOS，尤其是高密度对称能。
• 中子星观测和微观理论（例如 χEFT）提供互补约束，整合后塑造致密物质的推断EOS。

Figure 1.2: Constraints on the zeroth ( $S_{v}$ ) and first ( $L$ ) coefficient of the symmetry energy expansion. Experimental constraints are derived from heavy-ion collisions (HIC) [ 36 ] , neutron-skin thicknesses of Sn isotopes [ 37 ] , giant dipole resonances (GDR) [ 38 ] , the dipole polarizab