RUI: Constraining the Symmetry Energy of Neutron-Rich Nucleonic Matter at Supra-Saturation Densities

丰中子核物质的性质是自然界许多基本问题的核心。 目前正在世界各地利用各种先进的新设施进行实验性探索。 对于理解使用这些设备的各种新现象的实验观测来说，最关键的是对称能，它编码了与核物质中的中子-质子不对称有关的能量。 后者是目前在核物理学和天体物理学中正在深入研究的基本量。 核对称能的密度依赖性是描述中子星和丰中子核的结构以及重离子反应动力学的重要组成部分。 它还显著影响来自旋转和振荡中子星的引力波的应变振幅、频率和阻尼时间。 此外，由于额外时空维度的几何效应或粒子物理学标准模型的超对称扩展所预测的新玻色子的交换，对称能的高密度行为也与短距离下可能的非牛顿引力密切相关。 然而，我们目前对核对称能的认识，特别是在超饱和密度下的认识是非常贫乏的。 我的工作的最终目标是通过NSF的资助，利用核反应，特别是由高能稀有同位素束引起的核反应，确定致密富中子核子物质的对称能，并研究其对天体物理学和宇宙学的影响。 为了实现这一目标，将研究张量力、短程核子-核子关联函数的同位旋依赖性和三体力的自旋-同位旋依赖性对核对称能高密度行为的影响及其在核反应和中子星中的表现。 拟议的活动将对增进我们不仅在核物理学而且在天体物理学和宇宙学方面的知识产生重大影响。 此外，PI将通过积极参与研究生和本科生开展拟议的研究，促进研究，教学，培训和学习的更紧密结合。 该项目将帮助学生更好地准备成为下一代科学家和工程师。 此外，该项目还将进一步改善德克萨斯州农工大学商业学院的研究和教育基础设施和条件。

Properties of neutron-rich nuclear matter are at the heart of many fundamental questions in nature. They are currently being explored experimentally by using a wide variety of advanced new facilities around the world. Most critical to understanding experimental observations of various novel phenomena using these facilities is the symmetry energy, which encodes the energy related to neutron-proton asymmetry in nuclear matter. The latter is a fundamental quantity currently under intense investigation in both nuclear physics and astrophysics. The density dependence of nuclear symmetry energy is a vital ingredient in describing the structure of neutron stars and neutron-rich nuclei and the dynamics of heavy-ion reactions. It also influences significantly the strain amplitude, frequency and damping time of gravitational waves from both rotating and oscillating neutron stars. Moreover, the high-density behavior of the symmetry energy is also closely connected to the possible non-Newtonian gravity at short distance due to either the geometrical effects of extra space-time dimensions or the exchange of new bosons predicted by super-symmetric extensions of the Standard Model of particle physics. However, our current knowledge about the nuclear symmetry energy especially at super-saturation densities is very poor. The ultimate goal of my work supported by this NSF grant is to determine the symmetry energy of dense neutron-rich nucleonic matter using nuclear reactions especially those induced by high energy rare isotope beams and to examine its impacts on astrophysics and cosmology. To realize this goal, effects of the tensor force, isospin dependence of the short-range nucleon-nucleon correlation function and spin-isospin dependence of the three-body force on the high-density behavior of the nuclear symmetry energy and their manifestations in nuclear reactions and neutron stars will be investigated. The proposed activities will have significant impacts on advancing our knowledge not only in nuclear physics but also in astrophysics and cosmology. Moreover, the PI will promote more close integration of research, teaching, training, and learning by involving proactively both graduate and undergraduate students in carrying out the proposed research. This project will help better prepare students to become next generation scientists and engineers. Furthermore, the project will further enhance the infrastructure and conditions for both research and education at Texas A&M University-Commerce.