Theoretical Nuclear Physics

在核物理学中不断有许多令人兴奋的进展和发现。随着稀有同位素束设施的发展，与核物质中质子-中子不对称性有关的现象，对于了解中子星的性质和负责元素合成的恒星过程至关重要，现在可以在比迄今可能的范围更广的范围内进行研究。对于布鲁克海文国家实验室的相对论重离子对撞机（RHIC）提供的超相对论能量下的核碰撞，实验观察与物质的新相--夸克-胶子等离子体的产生相一致，夸克-胶子等离子体由质子和中子中的夸克和胶子组成，被认为在大爆炸后的第一微秒存在。在这个项目中，我们将继续发展各种能量的重离子碰撞的输运模型，包括稳定同位素和稀有同位素，并将理论预测与实验数据进行系统比较。对于涉及大中子或质子过剩的稀有同位素的碰撞，我们将扩展同位旋相关的输运模型，该模型包括质子和中子的不同动力学，也包括轻核的动力学和介质对产生的π介子的影响。 然后，我们将使用这个模型来研究核物质的能量依赖于它的密度和质子对中子的不对称性，通过两个核子的相关函数，轻核的生产，质子和中子之间的相对扩散，和带电π介子的比例。 对于超相对论重离子碰撞，我们将改进多相输运模型，它包括夸克和胶子的动力学和普通强子的动力学以及这两个物质相之间的过渡，通过使用准粒子图像来描述初始部分子物质，并包括强色场对部分子动力学的影响。 然后，该模型将被用来研究夸克胶子等离子体的性质，通过产生的光子，双轻子和粒子的光谱，包括重奇异夸克和魅力夸克，能量损失非常高的粒子产生的初始硬碰撞，电荷依赖的相关性，和事件的事件由事件产生的粒子的波动。我们将利用这些关于核物质和夸克胶子等离子体的研究所获得的知识，进一步研究有限核的结构和中子星的性质。 拟议的项目不仅直接影响现有放射性束加速器和未来的稀有同位素束设施（FRIB）以及RHIC和大型强子对撞机（LHC）的研究计划，而且还有助于理解天文学和粒子物理学中的许多重要问题。它还具有更广泛的影响，为参与的年轻学生和博士后研究人员提供广泛的研究经验，使他们为核科学或其他领域的职业生涯做好准备，继续为我们社会的科学和技术进步做出贡献。

Many exciting advances and discoveries are being continually made in nuclear physics. With the development of rare isotope beam facilities, phenomena associated with the proton-neutron asymmetry in nuclear matter, essential for understanding the properties of neutron stars and the stellar processes that are responsible for the synthesis of elements, can now be studied over a much broader range than hitherto possible. For collisions of nuclei at ultrarelativistic energies available from the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory, experimental observations are consistent with the creation of a new phase of matter, the quark-gluon plasma, that consists of the constituent quarks and gluons inside protons and neutrons and is believed to have existed during the first microsecond after the Big Bang. In this project, we will continue to develop transport models for heavy ion collisions at various energies and with both stable and rare isotopes and to carry out systematic comparisons of theoretical predictions with experimental data. For collisions involving rare isotopes of large neutron or proton excess, we shall extend the isospin-dependent transport model, which includes different dynamics for protons and neutrons, to include also the dynamics of light nuclei and the medium effects on produced pions. We will then use this model to study the dependence of the energy of nuclear matter on its density and proton to neutron asymmetry via the two-nucleon correlation functions, light nuclei production, the relative diffusion between protons and neutrons, and the ratio of charged pions. For ultra-relativistic heavy ion collisions, we will refine the multiphase transport model, which includes both the dynamics of quarks and gluons and that of ordinary hadrons as well as the transition between these two phases of matter, by using the quasi-particle picture to describe the initial partonic matter and including the effect of strong color fields on the parton dynamics. The model will then be used to study the properties of the quark-gluon plasma through the spectra of produced photons, dileptons, and particles that consist of heavy strange and charm quarks, the energy loss of very energetic particles produced from initial hard collisions, the charge-dependent correlations, and the event-by-event fluctuations of produced particles. With the knowledge acquired from these studies about nuclear matter and the quark-gluon plasma, we will further investigate the structure of finite nuclei and the properties of neutron stars. The proposed project has the intellectual merit of not only impacting directly the research programs at existing radioactive beam accelerators and the future Facility for Rare Isotope Beams (FRIB) as well as at RHIC and the Large Hadron Collider (LHC) but also contributing to the understanding of many important issues in astro- and particle physics. It also has the broader impact of providing participating young students and postdoctoral researchers a broad research experience that would prepare them well for careers in either nuclear science or other areas to continue their contributions to the scientific and technological advance in our society.