Fluctuations are one of the main probes of the physics of the new state of hot and dense nuclear matter called the Quark Gluon Plasma (QGP) which is created in the ultra-relativistic heavy ion collisions. In this dissertation we extend and improve upon the existing descriptions of heavy ion collisions in three different directions: we study the new signatures of initial state fluctuations, the propagation of perturbations in the early stages of the collision, and the effect of thermal fluctuations on the hydrodynamic expansion of the QGP.
First, in Chapter 3 we study initial state fluctuations by examining the complete statistical information contained in the two-particle correlation measurements in hydrodynamic simulations of Pb+Pb collisions at the CERN Large Hadron Collider (√sNN = 2.76 TeV). We use Principal Component Analysis (PCA) to decompose the spectrum of harmonic flow, v_n(p_T) for n = 0–5, into dominant components. The leading component is identified with the standard event plane vn(pT), while the subleading component describes additional fluctuations in the two-particle correlation function. We find good geometric predictors for the orientation and the magnitude of the leading and the subleading flows. The subleading v 0, v1, and v3 flow harmonics are shown to be a response to the radial excitation of the corresponding eccentricity ϵn. In contrast, for v2 the subleading flow in peripheral collisions is dominated by the nonlinear mixing between the leading elliptic flow and radial flow fluctuations. Nonlinear mixing also plays a significant role in generating subleading v4 and v 5 harmonics. The PCA gives a systematic way of studying the full information of the two-particle correlation matrix and identifying the subleading flows, which we show are responsible for factorization breaking in hydrodynamics.
Second, in Chapter 4 we study the thermalization and hydrodynamization of fluctuations at the early stages of heavy ion collisions. We use leading order effective kinetic theory, accurate at weak coupling, to simulate the pre-equilibrium evolution of transverse energy and flow perturbations. For the short evolution we can use a linear response theory to construct the pre-equilibrium Green functions. Then the energy-momentum tensor at a time when hydrodynamics becomes applicable can be expressed as a linear convolution of response functions with the initial perturbations. We propose combining effective kinetic theory with weak coupling initial state models, such as IP-Glasma, to model the complete pre-thermal evolution from saturated nuclei to hydrodynamics in a weak coupling framework.
Last, in Chapter 5 we consider out-of-equilibrium hydrodynamic fluctuations in the expanding QGP. We develop a set of kinetic equations for a correlator of thermal fluctuations which are equivalent to nonlinear hydrodynamics with noise. We first show that the kinetic response precisely reproduces the one-loop renormalization of the shear viscosity for a static fluid. We then use the hydro-kinetic equations to analyze thermal fluctuations for a Bjorken expansion. The steady state solution to the kinetic equations determine the coefficient of the first fractional power of the gradient expansion (∞ 1/(τ T)3/2), which was computed here for the first time. The formalism of hydro-kinetic equations can be applied to more general background flows and coupled to existing viscous hydrodynamic codes to incorporate the physics of hydrodynamic fluctuations.
|Advisor:||Teaney, Derek, Zingale, Michael|
|Commitee:||Jia, Jiangyong, Pisarski, Robert|
|School:||State University of New York at Stony Brook|
|School Location:||United States -- New York|
|Source:||DAI-B 78/12(E), Dissertation Abstracts International|
|Subjects:||High Temperature Physics, Physics, Nuclear physics|
|Keywords:||Equilibration, Fluctuations, Heavy ion collisions, Quark Gluon Plasma, Subleading flows, Thermal noise|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be