Elliptic flow and incomplete equilibration at RHIC

Bhalerao, Rajeev S.; Blaizot, Jean‐Paul; Borghini, Nicolas; Ollitrault, Jean-Yves

doi:10.1016/j.physletb.2005.08.131

Cited by 208 publications

(291 citation statements)

References 25 publications

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“…For Au+Au collisions at the top RHIC energy, √ s NN = 200 GeV, such calculations are in good agreement with the elliptic flow data at midrapidity [3,19]. From similar studies, it has been numerically established that, for not too large impact parameters, the final magnitude of the elliptic flow is proportional to the initial eccentricity used to characterize the spatial anisotropy in the transverse plane of the matter created in the overlap region of the colliding nuclei [15,20]. More generally, one expects the ratio of elliptic flow and eccentricity, v 2 / , at midrapidity to be a universal function of density and size of the system at the time when the elliptic flow develops (v 2 / scaling) [21][22][23].…”

Section: Introductionsupporting

confidence: 61%

See 1 more Smart Citation

Importance of correlations and fluctuations on the initial source eccentricity in high-energy nucleus-nucleus collisions

Alver¹,

Back²,

Baker³

et al. 2008

Phys. Rev. C

263

198

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In relativistic heavy-ion collisions, anisotropic collective flow is driven, event by event, by the initial eccentricity of the matter created in the nuclear overlap zone. Interpretation of the anisotropic flow data thus requires a detailed understanding of the effective initial source eccentricity of the event sample. In this paper, we investigate various ways of defining this effective eccentricity using the Monte Carlo Glauber (MCG) approach. In particular, we examine the participant eccentricity, which quantifies the eccentricity of the initial source shape by the major axes of the ellipse formed by the interaction points of the participating nucleons. We show that reasonable variation of the density parameters in the Glauber calculation, as well as variations in how matter production is modeled, do not significantly modify the already established behavior of the participant eccentricity as a function of collision centrality. Focusing on event-by-event fluctuations and correlations of the distributions of participating nucleons, we demonstrate that, depending on the achieved event-plane resolution, fluctuations in the elliptic flow magnitude v 2 lead to most measurements being sensitive to the root-mean-square rather than the mean of the v 2 distribution. Neglecting correlations among participants, we derive analytical expressions for the participant eccentricity cumulants as a function of the number of participating nucleons, N part , keeping nonnegligible contributions up to O(1/N 3 part ). We find that the derived expressions yield the same results as obtained from mixed-event MCG calculations which remove the correlations stemming from the nuclear collision process. Most importantly, we conclude from the comparison with MCG calculations that the fourth-order participant eccentricity cumulant does not approach the spatial anisotropy obtained assuming a smooth nuclear matter distribution. In particular, for the Cu+Cu system, these quantities deviate from each other by almost a factor of 2 over a wide range in centrality. This deviation reflects the essential role of participant spatial correlations in the interaction of two nuclei.

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Section: Introductionsupporting

confidence: 61%

“…9, the results of Ref. [20] indicate that part {4} differs very little from both the standard eccentricity s and the average reaction-plane eccentricity RP , the latter two being almost equal. Recently, the authors of Ref.…”

Section: Cumulants In the Extended Bando Approachmentioning

confidence: 91%

Importance of correlations and fluctuations on the initial source eccentricity in high-energy nucleus-nucleus collisions

Alver¹,

Back²,

Baker³

et al. 2008

Phys. Rev. C

263

198

View full text Add to dashboard Cite

show abstract

“…The Knudsen number for AuAu collisions at √ s N N = 200 GeV have been estimated by hydrodynamic and transport models. In hydrodynamical approach, the centrality dependent elliptic flow suggest [29,30] Kn ≈ 0.3 and 0.5 for the central and a semi-central AuAu events, respectively. A good agreement between the Boltzmann equation for dilute system and the relativistic dissipative fluid dynamics, the main tool to study the space-time evolution of the bulk matter formed in the relativistic heavy-ion collisions at RHIC, is established [31][32][33] for Kn< 0.5.…”

Section: Resultsmentioning

confidence: 96%

Thermalization in a small hadron gas system and high-multiplicity pp events

Sarkar

Ghosh

2017

Phys. Rev. C

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We study the system-size dependence of Knudsen number, a measure of degree of thermalization, for hadron resonance gas that follows the Lattice-QCD equation of state at zero chemical potential. A comparison between Knudsen numbers for the AuAu collisions at RHIC and the hadron gas of size similar to the size of high-multiplicity pp events at LHC, reassures the applicability of hydrodynamics in interpreting the features of particle production in high-multiplicity pp events.

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“…expansion and freeze-out of the participant matter. To take these effects into account we use an empirical formula suggested in [30]:…”

Section: Elliptic Flowmentioning

confidence: 99%

Elliptic flow and dissipation in heavy-ion collisions atElab≃(1–160)AGeV

et al. 2009

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Elliptic flow in heavy-ion collisions at incident energies E lab ≃ (1-160)A GeV is analyzed within the model of 3-fluid dynamics (3FD). We show that a simple correction factor, taking into account dissipative affects, allows us to adjust the 3FD results to experimental data. This single-parameter fit results in a good reproduction of the elliptic flow as a function of the incident energy, centrality of the collision and rapidity. The experimental scaling of pion eccentricity-scaled elliptic flow versus charged-hadron-multiplicity density per unit transverse area turns out to be also reasonably described. Proceeding from values of the Knudsen number, deduced from this fit, we estimate the upper limit the shear viscosity-to-entropy ratio as η/s ∼ 1 − 2 at the SPS incident energies. This value is of the order of minimal η/s observed in water and liquid nitrogen.

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Elliptic flow and incomplete equilibration at RHIC

Cited by 208 publications

References 25 publications

Importance of correlations and fluctuations on the initial source eccentricity in high-energy nucleus-nucleus collisions

Importance of correlations and fluctuations on the initial source eccentricity in high-energy nucleus-nucleus collisions

Thermalization in a small hadron gas system and high-multiplicity pp events

Elliptic flow and dissipation in heavy-ion collisions atElab≃(1–160)AGeV

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