Fluctuations of particle yield ratios in heavy-ion collisions

Abstract

Dynamical fluctuations of various particle yield ratios at different center-of-mass energies are studied. Assuming that the particle production in the hadronic final state takes place due to equilibrium chemical processes, the experimental results available so far are compared with the hadron resonance gas (HRG) model taking into account the limited momentum acceptance in heavy-ion collisions experiments against HRG. Degenerated light and conserved strange quarks are presumed at all incident energies. At SPS energies, HRG model provides a good description for the dynamical fluctuations in (K+ + K-)/(π+ + π-) strangeness particle ratio. The dynamical fluctuations of the non-strangeness (p + p̄) /(π+ + π-) ratio are also studied. To reproduce RHIC results, the quark phase space occupation factor γ have to be assigned should be higher values different than unity. These values are conjectured to manifest the hadronic phase transition to quark-gluon plasma. The results are also compared with string-hadronic cascade and hadron string dynamics models. The dependence on center-of-mass energy seems not to be monotonic. © 2012 IACS.