The Evolution-Dominated Hydrodynamics and the Pseudorapidity Distributions in Nucleus-Nucleus Collisions at Low Energies at the BNL Relativistic Heavy Ion Collider

In the context of evolution-dominated hydrodynamics, we discuss the pseudorapidity distributions of the charged particles produced in Au-Au and Cu-Cu collisions at the corresponding energies of √^SNN=19:6 and 22.4 GeV at BNL-RHIC. It is found that the evolution-dominated hydrodynamics alone can give a good description to the experimental measurements. This is di_erent from that in collisions at the maximum energy of √^SNN=200 GeV at BNL-RHIC or at √^SNN=2:76 TeV at CERN-LHC. Where, in addition to evolutiondominated hydrodynamics, the leading particles have to be taken into account in order to adequately explain the experimental observations.