DSpace Repository

# A Hydrodynamic Analysis of Collective Flow in Heavy-Ion Collisions

 dc.contributor.advisor Teaney, Derek en_US dc.contributor.author Yan, Li en_US dc.contributor.other Department of Physics. en_US dc.date.accessioned 2017-09-20T16:51:06Z dc.date.available 2017-09-20T16:51:06Z dc.date.issued 2013-12-01 en_US dc.identifier.uri http://hdl.handle.net/11401/76741 en_US dc.description 137 pg. en_US dc.description.abstract Recent progress in the hydrodynamic simulation of heavy-ion collisions have characterized the fluctuating initial state and the viscous corrections to the corresponding collective flow. These fluctuations naturally explain the " ridge" and " shoulder" structure of the measured two-particle correlation functions at RHIC and the LHC. We introduce a cumulant expansion for analyzing the azimuthal fluctuations in the initial state. The cumulant definitions systematically describe the azimuthal anisotropy order by order. In particular, the dipole asymmetry $\epsilon_1$ appears at third order in the expansion, and the response to this initial fluctuation produces a radipity even dipole flow $v_1$, which has been subsequently confirmed by experiment. In addition, the cumulant expansion organizes the study of the nonlinear response to the initial conditions. The linear and nonlinear response coefficients to a given initial state were calculated with ideal and viscous hydrodynamic simulations. The collective flow is generated either linearly or nonlinearly, and the relative contribution of these two mechanisms to the observed flow pattern is calculated as a function of harmonic order, collision centrality, and the shear viscosity. For non-central collisions and high harmonic orders $\nge 4$, the nonlinear response is the dominant mechanism. This result is also seen in event-by-event hydrodynamic simulations. Using the cumulant expansion and the corresponding linear and nonlinear response coefficients, we determine the event plane correlations and compare to first measurements of this type. The observed event plane correlations are rooted in the initial state participant plane correlations, but a large fraction of the observed correlations are determined by harmonic mixing during the bulk expansion. Viscous corrections to the hydrodynamic formulation of collective flow are reflected in hydrodynamic equations of motion, as well as the correction to the distribution function at freeze-out, $\delta f(x,\vec p)$. Taking into consideration of the connection between kinetic theory and hydrodynamics, the consistent form of $\delta f(x,\vec p)$ is determined through second order in the gradient expansion, $\delta f(x,vec p) = \delta f_{(1)}(x,\vec p) + \delta f_{(2)}(x,\vec p) + \ldots$, The effect of $\delta f_{(2)}(x,\vec p)$ is found to be small for lower order harmonic flows $\nleq3$, but is significant for the higher harmonics, $\ngeq 4$. In addition, the effect of $\delta f_{(2)}(x,\vec p)$ is small for nucleus-nucleus collisions at the LHC, but is more pronounced at RHIC and in small collision systems such as proton-nucleus collisions. $\delta f_{(2)}(x,\vec p)$ delineates the domain of applicability of viscous hydrodynamics, and systematically improves the hydrodynamic description of heavy ion collisions. en_US dc.description.sponsorship This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree. en_US dc.format Monograph en_US dc.format.medium Electronic Resource en_US dc.language.iso en_US en_US dc.publisher The Graduate School, Stony Brook University: Stony Brook, NY. en_US dc.subject.lcsh Physics en_US dc.subject.other collective flow, heavy-ion collisions, hydrodynamics en_US dc.title A Hydrodynamic Analysis of Collective Flow in Heavy-Ion Collisions en_US dc.type Dissertation en_US dc.mimetype Application/PDF en_US dc.contributor.committeemember Shuryak, Edward en_US dc.contributor.committeemember Dawber, Matthew en_US dc.contributor.committeemember Sorensen, Paul. en_US
﻿