FWF project: P 34455
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| Nonperturbative properties of evolving gluonic plasmas |
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Quantum Chromodynamics (QCD) is one of the four fundamental forces in the Standard Model of particle physics and among the most important building blocks of modern physics. It describes the interactions among quarks and gluons, which form nuclear matter (protons, neutrons and other hadrons) or, at extremely high temperatures of around 1012 °C, a quark-gluon plasma. This extreme state of matter has likely existed in the earliest instants of our universe after the Big Bang. On Earth, the quark-gluon plasma is created in ultra-relativistic heavy-ion collision experiments at large laboratory facilities like the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) at early times after the collision. In these experiments, the plasma behaves like a nearly perfect fluid after a very short time scale of the order of a few yoctoseconds ∼1 fm/c ≈ 3 × 10-24 s. Right after the collision, created quarks and gluons do not have the same energy distribution as in thermal equilibrium, and their non-equilibrium states can have very different properties. Understanding them at the initial stages that lead to the fluid-like behavior of the quark-gluon plasma constitutes a bottleneck in the analysis of heavy-ion collisions, from which description uncertainties and errors can propagate. Detailed knowledge of the early-time properties is not only necessary, but also opens new opportunities. For instance, early-time dynamics can influence transport coefficients. These are numbers that encode properties of the current state of the plasma and are core ingredients in phenomenological studies of experimental observables like heavy quarks or highly energetic particles (jets) in the plasma. This can lead to unique signatures of the early-time dynamics in heavy-ion collisions. Despite its significance, much is unknown about the non-equilibrium plasma. The goal of this research project is to gain a much deeper understanding of the pre-equilibrium dynamics of the quark-gluon plasma using nonperturbative simulation techniques and to find experimentally testable signatures of the early-time dynamics. By performing large-scale classical-statistical lattice simulations with large gluonic particle numbers, we focus on yet insufficiently understood nonperturbative properties of the plasma. Such include spectral information on quasiparticles in the plasma, gluon dynamics at large length scales, and the impact of the non-equilibrium plasma on transport coefficients and other observables. Moreover, the plasma exhibits universal self-similar dynamics when studied in extreme far-from-equilibrium conditions, and it has been conjectured to form a universality class with scalar field theories. In the project, we also want to scrutinize and to improve our understanding of this universality. This opens interdisciplinary opportunities linking heavy-ion collisions to ultra-cold atom experiments and to reheating after cosmological inflation. |