Dissertation/Thesis Abstract

Infrared Dynamics of Non-Abelian Gauge Theories out of Equilibrium
by Mace, Mark, Ph.D., State University of New York at Stony Brook, 2018, 188; 10930781
Abstract (Summary)

The initial moments after an ultrarelativistic nuclear collision present a unique opportunity to study the many-body dynamics of Quantum Chromodynamics (QCD) out of equilibrium. This system is highly occupied with gluons up to an emergent semi-hard scale, Qs, the saturation momentum. Because the coupling at early times is weak, systematic studies are possible using an effective theory of QCD, the Color Glass Condensate effective field theory (CGC EFT). In this dissertation, we use the CGC EFT to probe novel features of the infrared regime of far-from-equilibrium QCD systems.

The prospect of detecting the Chiral Magnetic Effect (CME) in ultrarelativistic heavy-ion collisions has generated great interest in real-time topological transitions, called sphaleron transitions, in QCD. Here chiral charge, anomalously produced by sphaleron transitions, generates an electric current when in the presence of the strong, but short-lived magnetic field created by the passing heavy-ions. This current can imprint itself on the detected hadrons: the search for this signal is a major focus of current and planned heavy-ion collision experiments at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Lab and the Large Hadron Collider (LHC) at CERN. Using first-principles-based real-time classical-statistical lattice gauge theory simulations, we demonstrate for the first time that sphaleron transitions occur in QCD out of equilibrium. By determining the time evolution of the characteristic scales in the system, we show that the rate of sphaleron transitions is controlled by the infrared screening scale. We then conclude that the rate of sphaleron transitions at early times is favorable for the generation of the CME. With the novel addition of chiral lattice fermions and a magnetic field, we investigate the real-time dynamics of anomalous transport phenomena, like the CME and the gapless excitation known as the Chiral Magnetic Wave (CMW), microscopically. Insights necessary for model building and phenomenology related to the search for the CME and the CMW are then discussed.

Long-range-in-rapidity correlations probe the early-time dynamics after the collision due to causality. In small systems, where final state effects are likely small, the study of such correlations potentially offers a unique opportunity to directly access the early-time infrared dynamics of the system. First, we present a proof-of-principle parton model for proton--heavy-ion collisions. With this simple model, we qualitatively reproduce many of the multiparticle correlations observed experimentally, which are often ascribed to final state collective flow. This serves as a clear demonstration that such correlations can be generated without a final state hydrodynamic medium. Next, we develop an event-by-event framework to study initial correlations of gluons in light--heavy-ion collisions. We show that key systematics in the observed two-particle correlations at RHIC and the LHC can be quantitatively reproduced with this framework. This suggests that the observed correlations may arise, at least in part, from the earliest times after the collision. If this bears out, it would imply that the long-range-in-rapidity correlations measured in small systems are a direct result of the infrared dynamics of far-from-equilibrium QCD.

Indexing (document details)
Advisor: Kharzeev, Dmitri, Venugopalan, Raju
Commitee: Drees, Axel, Dumitru, Adrian, Teaney, Derek
School: State University of New York at Stony Brook
Department: Physics
School Location: United States -- New York
Source: DAI-B 80/03(E), Dissertation Abstracts International
Subjects: Physics
Keywords: Color glass condensate, Heavy-ion, Infrared, Multiparticle correlations, Non-equilibrium, Sphaleron
Publication Number: 10930781
ISBN: 9780438572263
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