Centrality-Dependent Chemical Potentials of Light Hadrons and Quarks Based on <i>p</i>_<i>T</i> Spectrum and Particle Yield Ratio in Au-Au Collisions at RHIC Energies

Abstract

We analyze the pT spectra of π±, K±, p, and p¯ produced in different centralities’ Au-Au collisions at different collision energies from 7.7 to 62.4 GeV using a two-component Erlang distribution in the framework of a multi-source thermal model. The fitting results are consistent with the experimental data, and the yield ratios of negative to positive particles are obtained from the normalization constants. Based on the yield ratios, the chemical potentials of light hadrons (π, K, and p) and quarks (u, d, and s) are extracted. This study shows that only the yield ratios of p decrease with the increase in centrality. The logarithms of these yield ratios in the same centrality show obvious linear dependence on 1/sNN. The extracted chemical potentials (the absolute magnitude for π) of light hadrons and quarks decrease with the increase in energy. The curves of chemical potential vs. energy for all centralities derived from the linear fits of the logarithms of the yield ratio as a function of energy have their maximum (the absolute magnitude for π) at the same energy of 3.526 GeV, which is possibly the critical energy of phase transition from a liquid-like hadron state to a gas-like quark state in the collision system.

Keywords

• transverse momentum spectra
• yield ratio of negative to positive particles
• chemical potential of particle
• critical end point of phase transition