Constraining the viscous freeze-out distribution function with data obtained at the BNL Relativistic Heavy Ion Collider (RHIC)

Luzum, Matthew; Ollitrault, Jean-Yves

doi:10.1103/physrevc.82.014906

Cited by 24 publications

(20 citation statements)

References 26 publications

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“…The momentum dependence of this distortion is strongly model dependent [59]. The present calculation uses the standard quadratic ansatz, which may overestimate the viscous correction at large p t [60]. The magnitude and the centrality dependence of v 3 observed by STAR are rather well reproduced by our calculation with Glauber initial conditions, except for peripheral collisions, where hydrodynamics is not expected to be valid.…”

Section: Results and Comparison With Datamentioning

confidence: 60%

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Triangular flow in hydrodynamics and transport theory

et al. 2010

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In ultrarelativistic heavy-ion collisions, the Fourier decomposition of the relative azimuthal angle, \Delta \phi, distribution of particle pairs yields a large cos(3\Delta \phi) component, extending out to large rapidity separations \Delta \eta >1. This component captures a significant portion of the ridge and shoulder structures in the \Delta \phi distribution, which have been observed after contributions from elliptic flow are subtracted. An average finite triangularity due to event-by-event fluctuations in the initial matter distribution, followed by collective flow, naturally produces a cos(3\Delta \phi) correlation. Using ideal and viscous hydrodynamics, and transport theory, we study the physics of triangular (v_3) flow in comparison to elliptic (v_2), quadrangular (v_4) and pentagonal (v_5) flow. We make quantitative predictions for v_3 at RHIC and LHC as a function of centrality and transverse momentum. Our results for the centrality dependence of v_3 show a quantitative agreement with data extracted from previous correlation measurements by the STAR collaboration. This study supports previous results on the importance of triangular flow in the understanding of ridge and shoulder structures. Triangular flow is found to be a sensitive probe of initial geometry fluctuations and viscosity.Comment: 10 pages, 12 figures. minor changes, and results for $v_5$ added (fig.12

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Section: Results and Comparison With Datamentioning

confidence: 60%

“…At high p t , a strong viscous suppression is observed. As already explained, the p t dependence of the viscous correction is model dependent, and it is likely that the quadratic ansatz used here overestimates the viscous corrections at large p t [60]. Note that effects of resonance decays are not included in Fig.…”

Section: Results and Comparison With Datamentioning

confidence: 89%

Triangular flow in hydrodynamics and transport theory

et al. 2010

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“…[36]. The comparisons to hydrodynamic models can further help us to understand the viscous corrections to the momentum distributions at hadronic freeze-out [45,52,[54][55][56].…”

Section: -11mentioning

confidence: 99%

“…When the order of the harmonic is large, the nonlinear response contribution in viscous hydrodynamics is dominant and increases in more peripheral collisions [50,52]. The magnitudes of the viscous corrections as a function of p T for v 4 and v 5 are sensitive to the ansatz used for the viscous distribution function, a correction for the equilibrium distribution at hadronic freeze-out [52,54]. Hence, studies of the correlations between higher order (n > 3) and lower order (v 2 or v 3 ) harmonics and their p T dependence can help to understand the viscous correction to the momentum distribution at hadronic freeze-out which is among the least understood parts of hydrodynamic calculations [45,52,55,56].…”

Section: Introductionmentioning

confidence: 99%

Systematic studies of correlations between different order flow harmonics in Pb-Pb collisions at sNN=2.76 TeV

Acharya¹,

Adam²,

Adamová³

et al. 2018

Phys. Rev. C

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The correlations between event-by-event fluctuations of anisotropic flow harmonic amplitudes have been measured in Pb-Pb collisions at √ s NN = 2.76 TeV with the ALICE detector at the Large Hadron Collider.The results are reported in terms of multiparticle correlation observables dubbed symmetric cumulants. These observables are robust against biases originating from nonflow effects. The centrality dependence of correlations between the higher order harmonics (the quadrangular v 4 and pentagonal v 5 flow) and the lower order harmonics (the elliptic v 2 and triangular v 3 flow) is presented. The transverse momentum dependences of correlations between v 3 and v 2 and between v 4 and v 2 are also reported. The results are compared to calculations from viscous hydrodynamics and a multiphase transport (AMPT) model calculations. The comparisons to viscous hydrodynamic models demonstrate that the different order harmonic correlations respond differently to the initial conditions and the temperature dependence of the ratio of shear viscosity to entropy density (η/s). A small average value of η/s is favored independent of the specific choice of initial conditions in the models. The calculations with the AMPT initial conditions yield results closest to the measurements. Correlations among the magnitudes of v 2 , v 3 , and v 4 show moderate p T dependence in midcentral collisions. This might be an indication of possible viscous corrections to the equilibrium distribution at hadronic freeze-out, which might help to understand the possible contribution of bulk viscosity in the hadronic phase of the system. Together with existing measurements of individual flow harmonics, the presented results provide further constraints on the initial conditions and the transport properties of the system produced in heavy-ion collisions.

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“…We chose to do the former and using our analytic solution to the massless problem calculated the single power that best maximizes the functional. The answer we came up with was near 3 2 , a value which has been found in other theoretical and phenomenological studies [15] [16]. We then chose this momentum to the 3 2 power as our functional form of χ i and again calculated what the results for pion and proton elliptic flow would be assuming hydrodynamic freeze-out to a hadron gas.…”

Section: Results For a Multicomponent Hadron Gasmentioning

confidence: 74%

Self-consistent Cooper-Frye freeze-out of a viscous fluid to particles

Wolff

Molnár

2014

J. Phys.: Conf. Ser.

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Comparing hydrodynamic simulations to heavy-ion data inevitably requires the conversion of the fluid to particles. This conversion, typically done in the Cooper-Frye formalism, is ambiguous for viscous fluids. We compute self-consistent phase space corrections by solving the linearized Boltzmann equation and contrast the solutions to those obtained using the ad-hoc "democratic Grad" ansatz typically employed in the literature where coefficients are independent of particle dynamics. Solutions are calculated analytically for a massless gas and numerically for both a pion-nucleon gas and for the general case of a hadron resonance gas. We find that the momentum dependence of the corrections in all systems investigated is best fit by a power close to 3/2 rather than the typically used quadratic ansatz. The effects on harmonic flow coefficients v2 and v4 are substantial, and should be taken into account when extracting medium properties from experimental data.

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Constraining the viscous freeze-out distribution function with data obtained at the BNL Relativistic Heavy Ion Collider (RHIC)

Cited by 24 publications

References 26 publications

Triangular flow in hydrodynamics and transport theory

Triangular flow in hydrodynamics and transport theory

Systematic studies of correlations between different order flow harmonics in Pb-Pb collisions at sNN=2.76 TeV

Self-consistent Cooper-Frye freeze-out of a viscous fluid to particles

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