Charged-particle rapidity density in Au+Au collisions in a quark combination model

Abstract

Rapidity/pseudorapidity densities for charged particles and their centrality, rapidity, and energy dependence in Au+Au collisions at the Relativistic Heavy Ion Collider are studied in a quark combination model. Using a Gaussian-type rapidity distribution for constituent quarks as a result of Landau hydrodynamic evolution, the data at $\sqrt{{s}_{\mathit{NN}}}=130,200$ GeV at various centralities in full pseudorapidity range are well described, and the charged-particle multiplicities are reproduced as functions of the number of participants. The energy dependence of the shape of the ${\mathit{dN}}_{\mathit{ch}}/d\ensuremath{\eta}$ distribution is also described at various collision energies $\sqrt{{s}_{\mathit{NN}}}=200,130,62.4$ GeV in central collisions with same value of parameters except 19.6 GeV. The calculated rapidity distributions and yields for the charged pions and kaons in central Au+Au collisions at $\sqrt{{s}_{\mathit{NN}}}=200$ GeV are compared with experimental data of the BRAHMS Collaboration.