Dynamical freeze-out in three-fluid hydrodynamics

Russkikh, V. N.; Ivanov, Yu. B.

doi:10.1103/physrevc.76.054907

Cited by 46 publications

(68 citation statements)

References 77 publications

(122 reference statements)

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“…As it is illustrated in Ref. [58], the 3-fluid dynamics of nuclear system at 158A GeV is quite different from the Bjorken picture. This could be a reason of disagreement between our results and the results of Ref.…”

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confidence: 98%

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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Section: Discussionmentioning

confidence: 98%

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

et al. 2009

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“…Then the surface freeze-out occurs really at the value ε s ≈ ε frz and thus the actual freeze-out energy density saturates at the value ε out ≈ ε frz /2. This freezeout dynamics is quite stable with respect to numerics [15]. Figure 3 presents average temperatures, transverse velocities, baryon densities and chemical potentials achieved at the freeze-out in central collisions.…”

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confidence: 94%

“…In order to clarify why this happens, let us turn to the 3FD freeze-out procedure, which is analyzed in ref. [15] in more detail.…”

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confidence: 99%

“…[15]. At low (AGS) incident energies, the energy density achieved at the border with vacuum, ε s , is lower than ε frz .…”

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confidence: 99%

“…As explained in ref. [15], a natural value of this actual freeze-out energy density is ε out ≈ ε s /2, i.e. at that the middle of the fall from the near-surface value of the energy density, ε s , to zero.…”

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Transverse-mass effective temperature in heavy-ion collisions from AGS to SPS

Ivanov

Russkikh

2008

Eur. Phys. J. A

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Abstract. Transverse-mass spectra in Au + Au and Pb + Pb collisions in the incident energy range from 2A to 160A GeV are analyzed within the model of 3-fluid dynamics (3FD). It is shown that the dynamical description of freeze-out, accepted in this model, naturally explains the incident-energy behavior of the inverse-slope parameters of these spectra observed in experiment. The simultaneous reproduction of the inverse slopes of all considered particles (p, π and K) suggests that these particles belong to the same hydrodynamic flow at the instant of their freeze-out. PACS. 24.10.Nz Hydrodynamic models -25.75.-q Relativistic heavy-ion collisionsExperimental data on transverse-mass spectra of kaons produced in central Au + Au [1] or Pb + Pb [2] collisions reveal peculiar dependence on the incident energy. The inverse-slope parameter (the so-called effective temperature T ) of these spectra at mid rapidity increases with incident energy in the energy domain of BNL Alternating Gradient Synchrotron (AGS) and then saturates at the energies of CERN Super Proton Synchrotron (SPS). In refs. [3,4] it was assumed that this saturation is associated with the deconfinement phase transition. This assumption was indirectly confirmed by the fact that microscopic transport models, based on hadronic degrees of freedom, failed to reproduce the observed behavior of the kaon inverse slope [5,6]. Hydrodynamic simulations of ref. [7] succeeded to describe this behavior. However, in order to reproduce it these hydrodynamic simulations required incident-energy dependence of the freeze-out temperature which almost repeated the shape of the corresponding kaon effective temperature. This happened even in spite of using the equation of state (EoS) involving the phase transition into quark-gluon plasma (QGP). This way, the puzzle of kaon effective temperatures was just translated into a puzzle of freeze-out temperatures. Moreover, the results of ref. [7] imply that the peculiar incident-energy dependence of the kaon effective temperature may be associated with the dynamics of freeze-out. In this paper we would like to present calculations of effective temperatures within the 3FD model [8][9][10][11] which is suitable for simulating heavy-ion collisions in the range from AGS to SPS energies. We perform our simulations [8,10,11] with a simple, hadronic EoS [12], which involves only a density-dependent mean field providing saturation of cold nuclear matter at normal nuclear density and with the proper binding energy. The 3FD model with the intermediate EoS turned out to be able to reasonably reproduce a great body of experimental data [8] in a wide energy range from AGS to SPS. In particular, transversemass spectra of protons were reproduced. This was done with the unique set of model parameters summarized in ref. [8]. Problems were met only in the description of the transverse flow [10]. The directed flow requires a softer EoS at top AGS and SPS energies (in particular, this desired softening may signal the occurrence of the phase transition int...

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