Non-critical fluctuations of (net) charges and (net) protons from iEBE-VISHNU hybrid model

Abstract: In this paper, we investigate the non-critical fluctuations of (net) charges and (net) protons in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 39 and 200 GeV, using iEBE-VISHNU hybrid model with Poisson fluctuations added in the particle event generator between hydrodynamics and UrQMD. Various effects, such as volume fluctuations hadronic evolution and scatterings, resonance decays, as well as realistic centrality cuts and acceptance cuts have been embedded in our model calculations. With properly tuned parameters, iEBE-VISHNU roughly describe the centrality dependent moments and cumulants of (net) charges and (net) protons measured in experiment. Further comparison simulations show that the volume fluctuation is the dominant factor to influence the multiplicity fluctuations, which makes the higher moments of (net) charges largely deviate from the Poison baselines. We also find that the effects from hadronic evolutions and resonance decays are pretty small or even negligible for the multiplicity fluctuations of both (net) charges and (net) protons.