Initial State Fluctuations and Final State Correlations in Relativistic Heavy-Ion Collisions

Abstract

We review the phenomenology and theory of bulk observables in ultra-relativistic heavy-ion collisions, focussing on recent developments involving event-by-event fluctuations in the initial stages of a heavy ion collision, and how they manifest in observed correlations. We first define the relevant observables and show how each measurement is related to underlying theoretical quantities. Then we review the prevailing picture of the various stages of a collision, including the state-of-the-art modeling of the initial stages of a collision and subsequent hydrodynamic evolution, as well as hadronic scattering and freeze-out in the later stages. We then discuss the recent results that have shaped our current understanding and identify the challenges that remain. Finally, we point out open issues and the potential for progress in the field.

50 pages, 20 figures, replaced with published version as a topical review in JPG

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Cited by in corpus (128)

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• Dense Nuclear Matter Equation of State from Heavy-Ion Collisions
• Effective kinetic description of event-by-event pre-equilibrium dynamics in high-energy heavy-ion collisions
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• Measurement of the correlation between flow harmonics of different order in lead-lead collisions at $\sqrt{s_{NN}}$=2.76 TeV with the ATLAS detector
• Evidence of sub-nucleonic degrees of freedom in J/$\psi$ photoproduction in ultraperipheral collisions at the CERN Large Hadron Collider
• Event-by-event hydrodynamics $+$ jet energy loss: A solution to the $R_{AA}\otimes v_2$ puzzle
• Revealing long-range multi-particle collectivity in small collision systems via subevent cumulants
• A kinetic regime of hydrodynamic fluctuations and long time tails for a Bjorken expansion
• Collective flow in 2.76 A TeV and 5.02 A TeV Pb+Pb collisions
• Measurement of longitudinal flow de-correlations in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ and 5.02 TeV with the ATLAS detector
• Initial conditions for hydrodynamics from weakly coupled pre-equilibrium evolution
• Nonlinear Constraints on Relativistic Fluids Far From Equilibrium
• Effect of the QCD equation of state and strange hadronic resonances on multiparticle correlations in heavy ion collisions
• Transverse momentum fluctuations and their correlation with elliptic flow in nuclear collision
• Decorrelation of anisotropic flows along the longitudinal direction
• Viscous Effects on the Mapping of the Initial to Final State in Heavy Ion Collisions
• Theoretical and Experimental Constraints for the Equation of State of Dense and Hot Matter
• Chemical Equilibration in Hadronic Collisions
• Hydrodynamic Collectivity in Proton--Proton Collisions at 13 TeV
• Characterizing flow fluctuations with moments
• The smallest fluid on earth
• Forward-backward eccentricity and participant-plane angle fluctuations and their influences on longitudinal dynamics of collective flow
• Initial state fluctuations in collisions between light and heavy ions
• Event-shape fluctuations and flow correlations in ultra-relativistic heavy-ion collisions
• Hot QCD Phase Diagram From Holographic Einstein-Maxwell-Dilaton Models
• Ab Initio Coupling of Jets to Collective Flow in the Opacity Expansion Approach
• Longitudinal Decorrelation of Anisotropic Flows in Heavy-ion Collisions at the CERN Large Hadron Collider
• Cumulants and nonlinear response of high $p_T$ harmonic flow at $\sqrt{s_{NN}}=5.02$ TeV
• The QCD phase diagram and Beam Energy Scan physics: a theory overview
• Correlations of flow harmonics in 2.76A TeV Pb--Pb collisions
• Bulk viscosity from hydrodynamic fluctuations with relativistic hydro-kinetic theory
• Subleading harmonic flows in hydrodynamic simulations of heavy ion collisions
• Influence of temperature dependent shear viscosity on elliptic flow at back- and forward rapidities in ultrarelativistic heavy-ion collisions
• Causality violations in realistic simulations of heavy-ion collisions
• Shape and flow fluctuations in ultra-central Pb+Pb collisions at the LHC
• ${}^{16}{\mathrm{O}}^{16}\mathrm{O}$ at RHIC and the LHC comparing $\alpha$ clustering vs substructure
• Fluctuations of harmonic and radial flow in heavy ion collisions with principal components
• Event-by-event $v_n$ correlations of soft hadrons and heavy mesons in heavy ion collisions
• Freezing Out Fluctuations in Hydro+ Near the QCD Critical Point
• High order flow harmonics of identified hadrons in 2.76 A TeV Pb+Pb collisions
• Anisotropic distributions in a multi-phase transport model
• Transport coefficients of the quark-gluon plasma at the critical point and across the first-order line
• Hydrodynamization and non-equilibrium Green's functions in kinetic theory
• Hydrodynamic Predictions for Mixed Harmonic Correlations in 200 GeV Au+Au Collisions
• Azimuthal Anisotropy Distributions in High-Energy Collisions
• Establishing the Range of Applicability of Hydrodynamics in High-Energy Collisions
• Temperature and fluid velocity on the freeze-out surface from $\pi$, $K$, $p$ spectra in pp, p--Pb and Pb--Pb collisions
• Generic algorithm for multi-particle cumulants of azimuthal correlations in high energy nucleus collisions
• Fast resonance decays in nuclear collisions
• Anisotropic flow in transport+hydrodynamics hybrid approaches
• Development of transverse flow at small and large opacities in conformal kinetic theory
• Forward-backward multiplicity fluctuation and longitudinal harmonics in high-energy nuclear collisions
• Constraining the nucleon size with relativistic nuclear collisions
• Non-Gaussian eccentricity fluctuations
• Rapidity dependence of initial state geometry and momentum correlations in p+Pb collisions
• Anisotropic flow fluctuations in hydro-inspired freeze-out model for relativistic heavy ion collisions
• Critical lensing and kurtosis near a critical point in the QCD phase diagram in and out-of-equilibrium
• Jet Drift and Collective Flow in Heavy-Ion Collisions
• Continuous description of fluctuating eccentricities
• Observables for longitudinal flow correlations in heavy-ion collisions
• DREENA-A framework as a QGP tomography tool
• Direct Photon Elliptic Flow at BNL Relativistic Heavy Ion Collider (RHIC) and CERN Large Hadron Collider (LHC)
• Initial correlations of the Glasma energy-momentum tensor
• Momentum and its affiliated transport coefficients for a hot QCD matter in a strong magnetic field
• Building a testable shear viscosity across the QCD phase diagram
• Opacity dependence of transverse flow, pre-equilibrium and applicability of hydrodynamics in heavy-ion collisions
• Correlated wounded hot spots in proton-proton interactions
• Limitation of multi-particle correlations for studying the event-by-event distribution of harmonic flow in heavy-ion collisions
• Statistical analysis of initial state and final state response in heavy-ion collisions
• Collective Flow of QCD Matter: a Historical Introduction
• Influence of initial-state momentum anisotropy on the final-state collectivity in small collision systems
• Factorization breaking for higher moments of harmonic flow
• The Influence of Initial State Fluctuations on Heavy Quark Energy Loss in Relativistic Heavy-ion Collisions
• Event-by-event $v_n$ correlations of soft hadrons and heavy mesons in heavy ion collisions
• Fluctuations of anisotropic flow from the finite number of rescatterings in a two-dimensional massless transport model
• Methods for systematic study of nuclear structure in high-energy collisions
• Imaging nuclear shape through anisotropic and radial flow in high-energy heavy-ion collisions
• Hot and Dense QCD Shear Viscosity at Leading Log
• Centrality fluctuations and decorrelations in heavy-ion collisions
• Collective Expansion at the LHC: selected ALICE anisotropic flow measurements
• Multiparticle Production at Mid-Rapidity in the Color-Glass Condensate
• Observation of flow angle and flow magnitude fluctuations in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV at the CERN Large Hadron Collider
• A study of event-by-event fluctuations in relativistic heavy-ion collisions
• Applications of Persistent Homology in Nuclear Collisions
• Evolution of initial stage fluctuations in the glasma
• Effect of an electromagnetic field on the spectra and elliptic flow of particles
• Holographic entropy production in a Bjorken expanding hot and dense strongly coupled quantum fluid
• Multi-particle correlations, cumulants, and moments sensitive to fluctuations in rare-probe azimuthal anisotropy in heavy ion collisions
• Collective nuclear vibrations and initial state shape fluctuations in central Pb+Pb collisions: resolving the $v_2$ to $v_3$ puzzle
• Robustness of principal component analysis on harmonic flow in heavy ion collisions
• Event-by-Event Fluctuations Clusterization and Entropy Production in AA Collisions at AGS and SPS Energies
• Plane correlations in small colliding systems
• Hydrodynamic modeling of heavy-ion collisions
• Anisotropic Flow and Jet Quenching in Relativistic Nuclear Collisions
• On differences between even and odd anisotropic-flow harmonics in non-equilibrated systems
• Model comparison for initial density fluctuations in high energy heavy ion collisions
• Collective flow and hydrodynamics in large and small systems at the LHC
• Hydrodynamical corrections to electromagnetic emissivities in QCD
• Early time behavior of spatial and momentum anisotropies in kinetic theory across different Knudsen numbers
• Computational budget optimization for Bayesian parameter estimation in heavy ion collisions
• Fluctuations of pion flow harmonics and HBT correlation functions in ultrarelativistic heavy ion collisions
• Calculating charged particle observables using modified Wood Saxon model in HIJING for U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV
• Initial conditions for hydrodynamics from kinetic theory equilibration
• Influence of collective nuclear vibrations on initial state eccentricities in Pb+Pb collisions
• Higher-order symmetry plane correlations in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV
• Kinetic evolution and correlation of fluctuations in an expanding quark gluon plasma
• Topological charge fluctuations in the Glasma
• Distinguishing the sources of dielectron anisotropic flow at low beam energies
• Thermal fluctuations on the freeze-out surface of heavy-ion collisions and their impact on particle correlations
• Pseudorapidity dependence of anisotropic flow and its decorrelations using long-range multiparticle correlations in Pb-Pb and Xe-Xe collisions
• Probing Nuclear Geometry through Multi-Particle Azimuthal Correlations and Rapidity-Even Dipolar Flow in ${}^{16}$O+${}^{16}$O Collisions
• Bayesian reconstruction of anisotropic flow fluctuations at fixed impact parameter
• Event-by-event multiplicity fluctuations and correlations in ring-like and jet like events in ${}^{197}$Au-AgBr collisions at 11.6A GeV/c
• Decorrelation of participant and spectator angular momenta in heavy-ion collisions
• Cumulants of conserved charges in hydrodynamic simulations
• Emergent Viscous Hydrodynamics From a Single Quantum Particle
• Transport properties of a charged hot spot in an external electromagnetic field
• Solving the $R_{AA}\otimes v_2$ puzzle
• Heavy meson flow harmonics in event-by-event viscous relativistic hydrodynamics
• Overview of recent azimuthal correlation measurements from ALICE
• Universality of scaled particle spectra in ultrarelativistic heavy-ion collisions
• Statistical analysis of the fluctuations of an initial-state model with independently distributed hot spots
• Viscous Gubser flow with conserved charges to benchmark fluid simulations
• Hadronic Rescattering in pA and AA Collisions
• Collective phenomena in high-energy nuclear collisions
• Characterizing the initial conditions of heavy-ion collisions at the LHC with mean transverse momentum and anisotropic flow correlations
• Mixed Harmonic Correlations: Hydrodynamics Predictions at RHIC using Experimental Analysis Techniques