Chemical potentials of light flavor quarks from yield ratios of negative to positive particles in Au+Au collisions at RHIC

TL;DR

This study extracts the chemical potentials of light quarks in Au+Au collisions at various energies by analyzing particle yield ratios within a thermal model, revealing an exponential decrease with increasing collision energy.

Contribution

It provides a systematic extraction of light quark chemical potentials across a wide energy range using experimental yield ratios and a thermal model, which is a novel comprehensive analysis.

Findings

Chemical potentials decrease exponentially with collision energy.

Effective temperature increases with particle mass and energy.

Yield ratios can reliably determine quark chemical potentials.

Abstract

The transverse momentum spectra of $\pi^{-}$, $\pi^{+}$, $K^{-}$, $K^{+}$, $\bar{p}$, and $p$ produced in Au+Au collisions at center-of-mass energy $\sqrt{s_{NN}}=7.7$, 11.5, 19.6, 27, 39, 62.4, 130, and $200$ GeV are analyzed in the framework of a multisource thermal model. The experimental data measured at midrapidity by the STAR Collaboration are fitted by the (two-component) standard distribution. The effective temperature of emission source increases obviously with the increase of the particle mass and the collision energy. At different collision energies, the chemical potentials of up, down, and strange quarks are obtained from the antiparticle to particle yield ratios in given transverse momentum ranges available in experiments. With the increase of logarithmic collision energy, the chemical potentials of light flavor quarks decrease exponentially.