Abstract
Fluctuations of conserved quantities are sensitive observables to probe the signature of QCD phase transition and critical point in heavy-ion collisions. With the UrQMD model, we have studied the centrality and energy dependence of various order cumulants and cumulant ratios (up to fourth order) of net-proton, net-charge, and net-kaon multiplicity distributions in Au+Au collisions at , 11.5, 19.6, 27, 39, 62.4, 200 GeV. The model results show that the production mechanism of the particles and antiparticles has significant impact on the cumulants of net-particles multiplicity distributions and shows strong energy dependence. We also made comparisons between model calculations and experimental data measured in the first phase of the beam energy scan (BES) program by the STAR experiment at the BNL Relativistic Heavy Ion Collider. The comparisons indicate that the baryon conservation effect strongly suppresses the cumulants of net-proton distributions at low energies and the nonmonotonic energy dependence for the net-proton at the most central Au+Au collisions measured by the STAR experiment cannot be described by the UrQMD model. Since there has been no physics of QCD phase transition and QCD critical point implemented in the UrQMD, the model results provide us baselines and qualitative estimates about the noncritical background contributions to the fluctuations observables in heavy-ion collisions.
3 More- Received 29 October 2015
- Revised 16 April 2016
DOI:https://doi.org/10.1103/PhysRevC.94.024901
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