Charged particle rapidity distributions at relativistic energies

Using a multiphase transport model (AMPT), which includes both initial partonic and final hadronic interactions, we study the rapidity distributions of charged particles such as protons, antiprotons, pions, and kaons in heavy ion collisions at RHIC. The theoretical results for the total charged particle multiplicity at midrapidity are consistent with those measured by the PHOBOS Collaboration in central Au+Au collisions at √s=56 and 130A GeV. We find that these hadronic observables are much more sensitive to the hadronic interactions than to the partonic interactions.