Energy dependent chemical potentials of light particles and quarks from yield ratios of antiparticles to particles in high energy collisions

Abstract

We collect the yields of charged pions ($\pi^-$ and $\pi^+$), charged kaons ($K^-$ and $K^+$), anti-protons ($\bar p$), and protons ($p$) produced in mid-rapidity interval (in most cases) in central gold-gold (Au-Au), central lead-lead (Pb-Pb), and inelastic or non-single-diffractive proton-proton ($pp$) collisions at different collision energies. The chemical potentials of light particles and quarks are extracted from the yield ratios, $\pi^-/\pi^+$, $K^-/K^+$, and $\bar p/p$, of antiparticles to particles over an energy range from a few GeV to above 10 TeV. At a few GeV ($\sim4$ GeV), the chemical potentials show, and the yield ratios do not show, different trends comparing with those at other energies, though the limiting values of the chemical potentials and the yield ratios at very high energy are 0 and 1 respectively.