Title: Energy and centrality dependences of charged multiplicity density in relativistic nuclear collisions
Abstract: Using a hadron and string cascade model, JPCIAE, the experimental data of charged particle pseudorapidity density at mid-rapidity in both the relativistic p+p̄ collisions and the Au+Au collisions at snn=130 GeV were reproduced fairly well without retuning the model parameters. The predictions for full RHIC energy Au+Au collisions and for Pb+Pb collisions at the LHC energy were given. Participant nucleon distributions were calculated based on different methods. It was found that the number of participant nucleons, 〈Npart〉, is not a well defined variable both experimentally and theoretically. Thus, it is inappropriate to use charged particle pseudorapidity density per participant pair as a function of 〈Npart〉 for distinguishing various theoretical models.