Radiation and Transport in QCD Matter

在大爆炸后的几微秒内，宇宙充满了由夸克和胶子等基本粒子组成的极热等离子体。当膨胀的等离子体冷却到大约两万亿度的温度时，夸克和胶子就会凝聚成叫做强子的大质量束缚态，包括构成我们周围物质原子核的质子和中子。这种转变产生了宇宙中超过95%的可见质量，并将夸克和胶子永久地限制在强子中。这些现象是如何从夸克和胶子之间的强核力中产生的，这是现代科学中的一个前沿问题。重核的高能碰撞提供了一个独特的机会，可以在实验室里短暂地重现大爆炸的原始介质。从大型探测器中观察到的衰变产物来推断这种介质的性质是一项艰巨的挑战。PI将开发理论工具来诊断这个问题，并严格解释实验数据。PI将继续建立一个蓬勃发展的研究生研究项目，并通过星期六早晨物理项目促进地区高中生的科学推广。本项目旨在量化夸克-胶子等离子体（QGP）的基本输运性质以及强子质量如何在夸克-强子跃迁中出现。重夸克通过QGP的输运将使用创新的量子多体技术进行评估，其中重夸克相互作用将基于晶格离散量子色动力学（QCD）的第一性原理计算，这是强相互作用的基本理论。由此产生的重夸克输运系数将被应用到重离子碰撞形成的火球的最先进模拟中。此外，将计算这些火球的电磁辐射，以确定：(a)介质的温度，以及(b) QGP冷却时强子的质量如何出现。相对论重离子对撞机和大型强子对撞机当前和未来的实验项目都非常重视重夸克和电磁观测。通过该项目取得的进展将提供理论的严谨性和准确性，将精确数据的系统比较转化为关于原始QCD介质的可靠知识。

A few micro-seconds after the Big Bang the universe was filled with an extremely hot plasma made of elementary particles, the quarks and gluons. When the expanding plasma cooled to a temperature of about two trillion degrees, quarks and gluons condensed into massive bound states called hadrons, including the protons and neutrons which make up the atomic nuclei of the matter around us. This transition generated over 95% of the visible mass in the universe, and it permanently confined quarks and gluons into hadrons. How these phenomena emerge from the strong nuclear force between quarks and gluons is a forefront question in modern science. High-energy collisions of heavy nuclei provide a unique opportunity to recreate, for a short moment, the primordial medium of the Big Bang in the laboratory. It is a formidable challenge to infer the properties of this medium from its decay products observed in large detectors. The PI will develop theoretical tools to diagnose this matter and rigorously interpret the experimental data. The PI will continue to build a thriving graduate research program and foster scientific outreach to regional high school students through the Saturday Morning Physics program. This project aims at quantifying fundamental transport properties of the quark-gluon plasma (QGP) and how hadron masses emerge in the quark-to-hadron transition. The transport of heavy quarks through the QGP will be evaluated using innovative quantum many-body techniques, where the heavy-quark interactions will be based on first-principles computations of lattice discretized Quantum Chromodynamics (QCD), the fundamental theory of the strong interaction. The resulting heavy-quark transport coefficients will be implemented into state-of-the-art simulations of the fireballs formed in heavy-ion collisions. In addition, electromagnetic radiation from these fireballs will be calculated to determine: (a) the temperature of the medium, and (b) how the masses of hadrons emerge as the QGP cools down. Current and future experimental programs at the Relativistic Heavy-Ion Collider and Large Hadron Collider have a large emphasis on heavy-quark and electromagnetic observables. The advances achieved through this project will provide the theoretical rigor and accuracy required to convert systematic comparisons to precision data into robust knowledge about the primordial QCD medium.