Fluctuations of conserved charges within a Hadron Resonance Gas approach: chemical freeze-out conditions from net-charge and net-proton fluctuations

We present an analysis of fluctuations of conserved charges, as baryon number B and electric charge Q , using the Hadron Resonance Gas (HRG) model. The study of such observables within a theoretical approach and the comparison to experimental data on the moments of the multiplicity distributions of specific particles represents a useful tool to extract the chemical freeze-out parameters, temperature T and baryo-chemical potential μ B . In particular we calculate ratios of higher-order susceptibilities for net-protons and net-charge and we compare our results to the latest data from STAR collaboration. The effect of resonance decays and kinematic cuts applied in the experimental analysis in transverse momentum, rapidity and pseudo-rapidity are included in the calculation along with the randomization of nucleons occurring in the hadronic phase.