Universality of the saturation scale and the initial eccentricity in heavy ion collisions

Abstract

Recent estimates that Color Glass Condensate initial conditions may generate a larger initial eccentricity for noncentral relativistic heavy ion collisions (relative to the initial eccentricity assumed in earlier hydrodynamic calculations) have raised the possibility of a higher bound on the viscosity of the Quark Gluon Plasma. We show that this large initial eccentricity results in part from a definition of the saturation scale as proportional to the number of nucleons participating in the collision. A saturation scale proportional to the nuclear thickness function (and therefore independent of the probe) leads to a smaller eccentricity, albeit still larger than the value used in hydrodynamic models. Our results suggest that the early elliptic flow in heavy ion collisions (unlike multiplicity distributions) is sensitive to the universality of the saturation scale in high energy QCD.

arXiv comment5 pages, 3 figures, RevTEX

References in corpus (50)

• Experimental and Theoretical Challenges in the Search for the Quark Gluon Plasma: The STAR Collaboration's Critical Assessment of the Evidence from RHIC Collisions
• Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration
• Quark Gluon Plasma an Color Glass Condensate at RHIC? The perspective from the BRAHMS experiment
• The PHOBOS Perspective on Discoveries at RHIC
• Computing Quark and Gluon Distribution Functions for Very Large Nuclei
• Gluon Distribution Functions for Very Large Nuclei at Small Transverse Momentum
• Green's Functions in the Color Field of a Large Nucleus
• What RHIC Experiments and Theory tell us about Properties of Quark-Gluon Plasma ?
• The Intrinsic Glue Distribution at Very Small x
• Hadron production in nuclear collisions at RHIC and high density QCD
• Elliptic Flow of Identified Hadrons in Au+Au Collisions at sqrt(s_NN) = 200 GeV
• Azimuthal anisotropy in Au+Au collisions at sqrtsNN = 200 GeV
• Some Features of the Glasma
• Hadronic dissipative effects on elliptic flow in ultrarelativistic heavy-ion collisions
• Non-Abelian Weizsacker-Williams field and a two-dimensional effective color charge density for a very large nucleus
• Manifestations of high density QCD in the first RHIC data
• Gluon Production from Non-Abelian Weizsäcker-Williams Fields in Nucleus-Nucleus Collisions
• Gluon production in current-nucleus and nucleon-nucleus collisions in a quasi-classical approximation
• Gluon Production at High Transverse Momentum in the McLerran-Venugopalan Model of Nuclear Structure Functions
• Cronin Effect and High-p_T Suppression in pA Collisions
• The initial energy density of gluons produced in very high energy nuclear collisions
• Scaling of transverse energies and multiplicities with atomic number and energy in ultrarelativistic nuclear collisions
• Fock Space Distributions, Structure Functions, Higher Twists and Small x
• Non-perturbative computation of gluon mini-jet production in nuclear collisions at very high energies
• Production of gluons in the classical field model for heavy ion collisions
• Parton saturation and N_part scaling of semi--hard processes in QCD
• High energy pA collisions in the color glass condensate approach II. Quark production
• Collective non-Abelian instabilities in a melting Color Glass Condensate
• Coherent gluon production in very high energy heavy ion collisions
• Color Glass Condensate at the LHC: hadron multiplicities in $pp$, $pA$ and $AA$ collisions
• The Unstable Glasma
• The initial gluon multiplicity in heavy ion collisions
• High energy pA collisions in the color glass condensate approach I. Gluon production and the Cronin effect
• Saturation and Universality in QCD at small x
• Centrality and pseudorapidity dependence of elliptic flow for charged hadrons in Au+Au collisions at sqrt(sNN) = 200 GeV
• Elliptic flow and incomplete equilibration at RHIC
• Classical Gluon Radiation in Ultrarelativistic Nucleus-Nucleus Collisions
• Centrality Dependence of the Charged Particle Multiplicity near Mid-Rapidity in Au+Au Collisions at sqrt(s_NN) = 130 and 200 GeV
• How Protons Shatter Colored Glass
• The eccentricity in heavy-ion collisions from Color Glass Condensate initial conditions
• Classical Gluodynamics of High Energy Nuclear Collisions: an Erratum and an Update
• Gluon production in the Color Glass Condensate model of collisions of ultrarelativistic finite nuclei
• Energy density of the Glasma
• Yang-Mills Radiation in Ultra-relativistic Nuclear Collisions
• Nucleus-nucleus scattering in perturbative QCD with $N_c\to \infty$
• Probing colored glass via $q\bar{q}$ photoproduction
• Nuclear A-dependence near the Saturation Boundary
• Elliptic flow of colored glass in high energy heavy ion collisions
• Gluon Saturation Effects in Relativistic U+U Collisions
• Rapidity distribution of gluons in the classical field model for heavy ion collisions

Cited by in corpus (74)

• The Color Glass Condensate
• Viscosity Information from Relativistic Nuclear Collisions: How Perfect is the Fluid Observed at RHIC?
• Conformal Relativistic Viscous Hydrodynamics: Applications to RHIC results at sqrt(s_NN) = 200 GeV
• Hydrodynamic Modeling of Heavy-Ion Collisions
• Fluctuating Glasma initial conditions and flow in heavy ion collisions
• New Developments in Relativistic Viscous Hydrodynamics
• Physics of Strongly coupled Quark-Gluon Plasma
• Measurements of Higher-Order Flow Harmonics in Au+Au Collisions at sqrt(s_NN) = 200 GeV
• Triangular flow in hydrodynamics and transport theory
• Glasma flux tubes and the near side ridge phenomenon at RHIC
• Multiplicity scaling in ideal and viscous hydrodynamics
• Relativistic hydrodynamics for heavy-ion collisions
• The centrality dependence of elliptic flow, the hydrodynamic limit, and the viscosity of hot QCD
• Effects of fluctuations on the initial eccentricity from the Color Glass Condensate in heavy ion collisions
• Event-by-event hydrodynamics and elliptic flow from fluctuating initial state
• Pseudorapidity distribution and decorrelation of anisotropic flow within CLVisc hydrodynamics
• Determining initial-state fluctuations from flow measurements in heavy-ion collisions
• Wilson line correlator in the MV model: relating the glasma to deep inelastic scattering
• Elliptic flow of thermal photons in relativistic nuclear collisions
• Color Glass Condensate and Glasma
• Eccentricity fluctuation effects on elliptic flow in relativistic heavy ion collisions
• Mass ordering of differential elliptic flow and its violation for phi mesons
• Universal Flow in the First Stage of Relativistic Heavy Ion Collisions
• Role of quantum fluctuations in a system with strong fields: Onset of hydrodynamical flow
• Anisotropic flow in event-by-event ideal hydrodynamic simulations of sqrt(s_{NN})=200 GeV Au+Au collisions
• Understanding anisotropy generated by fluctuations in heavy-ion collisions
• Relative flow fluctuations as a probe of initial state fluctuations
• Early Time Dynamics of Gluon Fields in High Energy Nuclear Collisions
• Collective phenomena in non-central nuclear collisions
• Early collective expansion: Relativistic hydrodynamics and the transport properties of QCD matter
• Thermalization, Isotropization and Elliptic Flow from Nonequilibrium Initial Conditions with a Saturation Scale
• Implications of space-momentum correlations and geometric fluctuations in heavy-ion collisions
• Constraining models of initial conditions with elliptic and triangular flow data
• On the gluon spectrum in the glasma
• Elliptic Flow from Non-equilibrium Initial Condition with a Saturation Scale
• Relativistic Fluid Dynamics In and Out of Equilibrium -- Ten Years of Progress in Theory and Numerical Simulations of Nuclear Collisions
• Constraining relativistic viscous hydrodynamical evolution
• Small x physics and RHIC data
• Elliptic flow of thermal dileptons in relativistic nuclear collisions
• Initial eccentricity fluctuations and their relation to higher-order flow harmonics
• Energy and system-size dependence of two- and four-particle $v_2$ measurements in heavy-ion collisions at RHIC and their implications on flow fluctuations and nonflow
• Eccentricity distributions in nucleus-nucleus collisions
• Entropy production in high-energy heavy-ion collisions and the correlation of shear viscosity and thermalization time
• Effects of flow fluctuations and partial thermalization on $v_4$
• Elliptic Flow from a Hybrid CGC, Full 3D Hydro and Hadronic Cascade Model
• Initial energy density and gluon distribution from the Glasma in heavy-ion collisions
• Color Glass Condensate and Glasma
• Heavy Ion Collisions with Transverse Dynamics from Evolving AdS Geometries
• Elliptic flow fluctuations in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV
• Azimuthal Anisotropy Distributions in High-Energy Collisions
• Elliptic flow in nuclear collisions at the Large Hadron Collider
• New paradigm for fluctuations in heavy-ion collisions
• Elliptic Flow: A Study of Space-Momentum Correlations In Relativistic Nuclear Collisions
• Initial State Quantum Fluctuations in the Little Bang
• Initial state and thermalization in the Color Glass Condensate framework
• Azimuthal anisotropy: transition from hydrodynamic flow to jet suppression
• Predictions for the LHC heavy ion programme
• Azimuthal anisotropy measurements of strange and multistrange hadrons in U+U collisions at $\sqrt{s_{NN}}=193$ GeV at the BNL Relativistic Heavy Ion Collider
• Phenomenology of the little bang
• From Glasma to Quark Gluon Plasma in heavy ion collisions
• Elliptic flow of thermal photons and dileptons
• Quantitative and Conceptual Considerations for Extracting the Knudsen Number in Heavy Ion Collisions
• Statistical analysis of initial state and final state response in heavy-ion collisions
• Initial indications for the production of a strongly coupled plasma in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV
• Glauber-based evaluations of the odd moments of the initial eccentricity relative to the even order participant planes
• Constraints on models for the initial collision geometry in ultra relativistic heavy ion collisions
• Longitudinal dependence of open heavy flavor $R_{\text{AA}}$ in relativistic heavy-ion collisions
• Initial State: Theory Status
• Initial conditions of heavy ion collisions and small x
• Multiparticle production in the Glasma at NLO and plasma instabilities
• Anisotropic flow: Achievements, Difficulties, Expectations
• Relativistic Heavy Ion Collisions: Viscous Hydrodynamic Simulations and Final State Interactions
• RHIC data and small x physics
• Relativistic Viscous Hydrodynamics for High Energy Heavy Ion Collisions