Radiation and Transport in QCD Matter

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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.