Far-from-equilibrium properties of the strongly coupled quark-gluon plasma

Author(s)

Renato Anselmo Júdica Critelli

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Física (IF/SBI)
• Defense date: 2019-05-23

Examining board members

Jorge Jose Leite Noronha Junior; Eduardo Souza Fraga; Betti Hartmann; Matthew William Luzum; Jun Takahashi

• Advisor: Jorge Jose Leite Noronha Junior

Abstract

Quantum Chromodynamics (QCD) is the fundamental theory that governs the strong interaction, whose fundamental particles are quarks and gluons. In terms of energy scales, QCD is characterized by asymptotic freedom (approximately free quarks and gluons) and color confinement (quarks and gluons confined inside hadrons), where the former can be treated perturbatively and the latter is an intrinsic non-perturbative phenomenon. At finite temperature, hadronic matter undergoes a crossover phase transition from a gas of hadrons to the quark-gluon plasma (QGP) as the temperature increases. Near the crossover, where hadrons ``melt\'\' to release quarks and gluons, QCD is in its non-perturbative regime and the QGP is strongly coupled, posing great challenges for analytical studies. The so-called AdS/CFT duality, also known as holography, comes to offer a unique opportunity to study the QGP by providing a map between strongly coupled theories (which are generally very hard to solve) and a classical theory of gravity. On the experimental front, the study of the QGP is carried out in particle accelerators by colliding ultrarelativistic heavy ions. In these experiments, the QGP created undergoes rapid expansion and there is a very intricate interplay between soft and hard scales, from initial conditions to final the stream of particles. This scenario makes it evident that one must understand the QGP also out of equilibrium. Fortunately, holography is well suited for this task. By solving the time dependent Einstein\'s equations, using general techniques previously employed in numerical general relativity, one can study non-equilibrium phenomena of strongly coupled plasmas. Furthermore, the QCD phase diagram on the (T,mu_B) plane, where T is the temperature and mu_B the baryon chemical potential, remains largely unknown due to its non-perturbative aspects. In particular, it is conjectured the existence of a critical point delimiting the crossover region from the first order phase transition. Motivated by these facts, this thesis employs holography to analyze the role of the critical point on far-from-equilibrium dynamics. For instance, it is investigated how the critical point affects the time that it takes for a strongly coupled plasma to display hydrodynamic behavior starting from a far-from-equilibrium initial state. (AU)

• FAPESP's process: 16/09263-2 - Out-of-equilibrium properties of the strongly coupled quark-gluon plasma
• Grantee: Renato Anselmo Judica Critelli
• Support Opportunities: Scholarships in Brazil - Doctorate