Speed of Sound Parameter from RHIC and LHC Heavy-Ion Data

Self Cite

We propose a new revised Landau hydrodynamic model to study systematically the pseudorapidity distributions of charged particles produced in heavy ion collisions over an energy range from a few GeV to a few TeV per nucleon pair. The interacting system is divided into three sources namely the central, target, and projectile sources respectively. The large central source is described by the Landau hydrodynamic model and further revised by the contributions of the small target/projectile sources. In the calculation, to avoid the errors caused by an unapt conversion or non-division, the rapidity and pseudorapidity distributions are obtained respectively. The modeling results are in agreement with the available experimental data at relativistic heavy ion collider (RHIC), large hadron collider (LHC), and other energies for different centralities. The value of square speed of sound parameter in different collisions has been extracted by us from the widths of rapidity distributions. Our results show that, in heavy ion collisions at RHIC and LHC energies, the central source undergoes through a phase transition from hadronic gas to quark-gluon plasma (QGP) liquid phase; meanwhile, the target/projectile sources remain in the state of hadronic gas. The present work confirms that the QGP is of liquid type rather than that of a gas. The whole region of participants undergoes through a mixed phase consisting of a large quantity of (>90%) QGP liquid and a small quantity of (<10%) hadronic gas.

Section: Comparisons With Experimental Datamentioning

confidence: 85%

On Pseudorapidity Distribution and Speed of Sound in High Energy Heavy Ion Collisions Based on a New Revised Landau Hydrodynamic Model

Gao

Liu

2015

Self Cite

“…where 1 is the 1st order modified Bessel function. In analyses, the sound speed in hadronic state takes the value of ℎ = 0.35 [43,[44][45][46]. The critical temperature takes the value of = 0.18 GeV [47].…”

Section: (3) the Transverse Momentum Distributions Of Charged Particlmentioning

confidence: 99%

A Description of the Transverse Momentum Distributions of Charged Particles Produced in Heavy Ion Collisions at RHIC and LHC Energies

Hui

Jiang

2018

By assuming the existing of memory effects and long-range interactions in the hot and dense matter produced in high energy heavy ion collisions, the nonextensive statistics together with the relativistic hydrodynamics including phase transition is used to discuss the transverse momentum distributions of charged particles produced in heavy ion collisions. It is shown that the combined contributions from nonextensive statistics and hydrodynamics can give a good description to the experimental data in Au+Au collisions at √ = 200 GeV and in Pb+Pb collisions at √ = 2.76 TeV for ± , ± in the whole measured transverse momentum region, and for ( ̅ ) in the region of ≤ 2.0 GeV/c. This is different from our previous work, where, by using the conventional statistics plus hydrodynamics, the describable region is only limited in ≤ 1.1 GeV/c. Keywords：Nonextensive statistics; relativistic hydrodynamics; phase transition; transverse momentum distribution PACS Number(s): 25.75.Ag, 25.75.Ld, 25.75.Dw, 13.85.-t distributions [9-12], have been extensively studied in nuclear collisions at both RHIC and LHC energies. These investigations have shown a fact that the matter created in these collisions is in the state of strongly coupled quark-gluon plasma (sQGP) exhibiting a clear collective behavior nearly like a perfect fluid with very low viscosity [13-31]. Therefore, the movement of sQGP can be described in the scope of relativistic hydrodynamics which connects the static aspects of sQGP and the dynamical aspects of heavy ion collisions [32]. In our previous work [33], by considering the effects of thermalization, we once used a hydrodynamic model incorporating phase transition in analyzing the transverse momentum distributions of identified charged particles produced in heavy ion collisions. In that model, the quanta of hot and dense matter are supposed to observe the standard statistical distributions and the experimental measurements in Au+Au collisions at √ = 200 and 130 GeV can be well matched up in the region of ≤ 1.1 GeV/c. Known from the investigations in Ref. [34, 35], the memory effects and long-range force might appear in the hot and dense matter. This guarantees, at least to a certain extent, the reasonableness of nonextensive statistical approach in describing the thermal motions of quanta of hot and dense matter. Hence, in this paper, on the basis of hydrodynamics taking phase transition into considerations, we will use nonextensive statistics instead of conventional statistics to simulate the transverse collective flow of the matter created in collisions. The nonextensive statistics is also known as Tsallis nonextensive thermostatistics, which was first proposed by C. Tsallis in 1988 in his pioneering work [36]. This statistical theory overcomes the shortcomings of the conventional statistics in many physical problems with long-range interactions, long-range microscopic memory, or fractal space-time constrains. It has a wide range of applications in astrophysical self-gravitating systems [37], cosmology [38], the sola...

“…ℎ in (15) takes the values of ℎ = 0.45 and 0.42 for √ NN = 200 and 62. 4 GeV from the investigations of [15,[39][40][41]. in (15) takes the well-recognized value of = 180 MeV.…”

Section: (3) the Pseudorapidity Distributions Of Charged Particlesmentioning

confidence: 99%

A Description of Pseudorapidity Distributions of Charged Particles Produced in Au+Au Collisions at RHIC Energies

Jiang

Huang

2018

In heavy ion collisions, charged particles come from two parts: the hot and dense matter and the leading particles. In this paper, the hot and dense matter is assumed to expand according to the hydrodynamic model including phase transition and decouples into particles via the prescription of Cooper-Frye. The leading particles are as usual supposed to have Gaussian rapidity distributions with the number equaling that of participants. The investigations of this paper show that, unlike low energy situations, the leading particles are essential in describing the pseudorapidity distributions of charged particles produced in high energy heavy ion collisions. This might be due to the different transparencies of nuclei at different energies.