Alternative scenarios of relativistic heavy-ion collisions. II. Particle production

Particle production in relativistic collisions of heavy nuclei is analyzed in a wide range of incident energies 2.7 GeV <= root s(NN) <= 62.4 GeV. The analysis is performed within the three-fluid model employing three different equations of state (EoSs): a purely hadronic EoS, an EoS with the first-order phase transition, and an EoS with a smooth crossover transition. It is found that the hadronic scenario fails to reproduce experimental yields of antibaryons (strange and nonstrange), starting already from lower Super Proton Synchrotron (SPS) energies, i.e., root s(NN) > 5 GeV. Moreover, at energies above the top SPS one, i.e., root s(NN) > 17.4 GeV, the midrapidity densities predicted by the hadronic scenario considerably exceed the available Relativistic Heavy-Ion Collider data on all species. At the same time the deconfinement-transition scenarios reasonably agree (to a various extent) with all the data. The present analysis demonstrates certain advantage of the deconfinement-transition EoSs. However, all scenarios fail to reproduce the strangeness enhancement in the incident energy range near 30 A GeV (i.e., a horn anomaly in the K+/pi(+) ratio) and yields of phi mesons at 20 A-40 A GeV.