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

In framework of combing the participant-spectator model and the Landau hydrodynamic model, the pseudorapidity distributions of charged particles produced in heavy-ion (or nucleus-nucleus) collisions at RHIC and LHC energies are described by a modified Landau hydrodynamic model, where the Landau hydrodynamic model is applied to the target/projectile spectators and the target/projectile participants, respectively. The modeling results are in agreement with the PHOBOS and ALICE experimental data. Then, the values of square speed of sound (c²_s ) for the participants and spectators can be obtained from the widths of charged particle pseudorapidity distributions. Some features of c²_s for different centralities and center-of-mass energies are obtained too. [ABSTRACT FROM AUTHOR]