Energy and Centrality Dependence of Chemical Freeze-out Thermodynamics parameters

Abstract

Driven by the Beam Energy Scan (BES) program at the RHIC, researches and discussions on the QCD phase diagram have flourished recently. In order to provide a reference from microscopic transport models, we performed a systematic analysis, using a multiphase transport (AMPT) model for the particle yields and a statistical model (THERMUS) for the thermal fit, for Au+Au collisions at $\sqrt{s_{\text{NN}}}$=7.7-200 GeV. It is found that at a fixed collision centrality the chemical freeze-out parameter, temperature $T_{\text{ch}}$, increases with collision energy and somehow saturates at certain values of $T_{\text{ch}}$ in collisions near $\sqrt{s_{\text{NN}}}$=10 GeV, indicating the limiting temperature in hadronic interactions; meanwhile the baryon chemical potential ${\mu }_B$ decrease with the collision energy. The saturation temperature is also found to be dependent on partonic interaction. At a given collision energy, it is found that both $T_{\text{ch}}$ and ${\mu }_B$ decrease towards more peripheral collisions in the grand canonical approach. The energy and centrality dependence of other chemical freeze-out parameters, strangeness chemical potential ${\mu }_S$, strangeness undersaturation factor ${\gamma }_S$, and the volume of the fireball $V$ are also presented in this paper. The chemical potential ratio ${\mu }_s/{\mu }_B$ is also compared with lattice QCD calculation. The AMPT default model gives better descriptions on both the particle yields and the chemical freeze-out parameters than those from the AMPT string-melting model.

arXiv comment9 pages, 6 figures

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Cited by in corpus (5)

• Centrality dependence of chemical freeze-out parameters from net-proton and net-charge fluctuations using hadron resonance gas model
• Nucleon-number scalings of anisotropic flows and nuclear modification factor for light nuclei in the squeeze-out region
• Scaling of nuclear modification factors for hadrons and light nuclei
• Probing fluctuations and correlations of strangeness by net-kaon cumulants in Au+Au collisions at $\sqrt{s_{NN}}=7.7$ GeV
• Impact of spin polarization on transport and thermodynamic coefficients