RUI: Probing QCD with a Magnetic Field

正常物质是由电子和原子核组成的原子，原子核是由中子和质子组成的，中子和质子是由上下夸克组成的。相比之下，致密恒星的核心密度非常大，一个包含中子星物质的小盒子的质量约为1300万吨。在如此致密的介质中，中子受到如此大的挤压，以至于它们内部的夸克被解放了。这种恒星密集的物质经常也会受到非常大的磁场的影响。一类特殊的中子星，被称为磁星，其表面磁场比太阳磁场强15个数量级，核心磁场甚至更强。在这种情况下，核理论界的一个重要目标是了解极端条件下物质的相，以便做出理论预测，然后与地球上的观测数据和实验测量进行比较。特别是，该项目将通过研究在相对论重离子对撞机（RHIC）上进行的重离子碰撞实验的结果，探索极端条件下物质的性质。RHIC的实验产生的物质温度比太阳高1000倍，磁场比太阳磁场强18个数量级。研究生和本科生将有充分的培训机会，在这个项目中获得的技能将对他们未来的职业生涯有很好的帮助。尽管近年来关于在重离子碰撞实验中形成的夸克-胶子等离子体（QGP）的性质获得了丰富的信息，但仍有许多有待发现。例如，已知在这些碰撞中形成的QGP是一种完美的液体，但在高密度和低温下取代“液体”QGP的物质状态尚不清楚。这个项目将调查其中的一些问题。PI和他的合作者将使用量子场论中的非微扰方法来研究磁场对高温低密度（QGP相）夸克物质输运性质的影响；在高密度和低温下，实现了空间非均匀相，即双手性密度波相和轴子电动力学。为了完成这个项目，PI将制定具有异常输运的相对论等离子体的运动学，这些等离子体与具有不对称谱的夸克准粒子产生的Berry曲率有关。此外，PI将把最近在弱耦合极限下的反磁催化工作扩展到强耦合情况下，以完成超越平均场近似的解析计算与晶格QCD结果之间的类比。这些研究将为通过宏观观测特征探测高密度夸克物质的微观物理提供新的见解。这些研究将有助于建立核物理学、凝聚态物质和天体物理学之间的联系。

Normal matter is made of atoms consisting of electrons and nuclei, nuclei are made of neutrons and protons, and neutrons and protons are made of up and down quarks. In contrast, the cores of compact stars are so dense that a tiny box containing neutron-star matter would have a mass of about 13 million tons. Neutrons in such a dense medium get so squeezed that the quarks inside them become liberated. Quite often this stellar dense matter will be also subjected to very large magnetic fields. A special class of neutron stars, known as magnetars, can have surface magnetic fields that are fifteen orders of magnitude stronger than the magnetic field of the Sun and even much stronger fields in the core. In this context, an important goal of the nuclear theory community is to understand the phases of matter under extreme conditions in order to make theoretical predictions that can then be compared with observational data and experimental measurements made on Earth. In particular, this project will explore the properties of matter under extreme conditions by studying results from heavy-ion collision experiments carried out at the Relativistic Heavy-Ion Collider (RHIC). Experiments at RHIC produce matter at temperatures a thousand times hotter than the Sun and magnetic fields eighteen orders of magnitude stronger than the Sun's magnetic field. Graduate and undergraduate students will have ample training opportunities, and the skills acquired in this project will serve them well in their future professional careers.Despite the wealth of information gained in recent years about the properties of the quark-gluon plasma (QGP) formed in heavy-ion collision experiments, much still remains to be discovered. For example, it is known that the QGP formed in these collisions is a perfect liquid, but the state of matter that replaces the "liquid" QGP at higher densities and lower temperatures is yet to be understood. This project will investigate some of these problems. The PI and his collaborators will use nonperturbative methods in quantum field theory to investigate the influence of a magnetic field on the transport properties of quark matter at high temperatures and low densities (in the QGP phase); and at high densities and low temperatures, where the spatially inhomogeneous phase known as the Dual Chiral Density Wave phase and axion electrodynamics are realized. To carry out this project, the PI will formulate the kinematics of relativistic plasmas with anomalous transport associated with a Berry curvature produced by quark quasiparticles with asymmetric spectra. In addition, the PI will extend recent work on inverse magnetic catalysis in the weak-coupling limit to the strong-coupling regime case to complete the analogy between analytical calculations beyond the mean-field approximation and lattice QCD results. These studies will give new insights on probing the microscopic physics of high dense quark matter through macroscopically observable signatures. These studies will help establish connections between nuclear physics, condensed matter, and astrophysics.