RUI: Probing QCD with a Magnetic Field

正常物质由电子和原子核组成的原子组成，原子核由中子和质子组成，中子和质子由上夸克和下夸克组成。相比之下，致密恒星的核心密度如此之高，以至于一个包含中子星物质的微小盒子的质量约为1300万吨。在如此稠密的介质中，中子受到如此挤压，以至于其中的夸克得到了解放。通常，这种恒星致密物质也会受到非常大的磁场的影响。一类特殊的中子星，称为磁星，其表面磁场可能比太阳的磁场强15个数量级，核心磁场甚至更强。在这方面，核理论界的一个重要目标是了解极端条件下物质的相态，以便作出理论预测，然后与在地球上进行的观测数据和实验测量相比较。特别是，这个项目将通过研究相对论重离子对撞机(RHIC)上进行的重离子碰撞实验的结果来探索极端条件下物质的性质。RHIC的实验产生了比太阳热1000倍的物质和比太阳磁场强18个数量级的磁场。研究生和本科生将有大量的培训机会，在这个项目中获得的技能将在他们未来的职业生涯中很好地服务。尽管近年来关于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的东西。例如，众所周知，在这些碰撞中形成的QGP是一种完美的液体，但在更高密度和更低温度下取代“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夸克物质在高温和低密度(在QGP相中)以及在高密度和低温下的输运性质的影响，在那里实现了被称为双手征密度波相和轴子电动力学的空间不均匀相。为了执行这个项目，PI将描述相对论等离子体的运动学，这些等离子体具有反常输运，与具有不对称光谱的夸克准粒子产生的Berry曲率有关。此外，PI将把最近关于弱耦合极限下逆磁催化的工作推广到强耦合情形，以完成平均场近似以外的分析计算与晶格QCD结果之间的相似。这些研究将为通过宏观可观测的特征来探索高密度夸克物质的微观物理提供新的见解。这些研究将有助于在核物理、凝聚态物质和天体物理之间建立联系。

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.