We report the measurement of cumulants ($C_n,n=1,...,4$) of the net-charge distributions measured within pseudorapidity ($\left|\eta \right|<0.35$) in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{{}_{NN}}}=7.7–200\mathrm{GeV}$ with the PHENIX experiment at the Relativistic Heavy Ion Collider. The ratios of cumulants (e.g., $C_1/C_2, C_3/C_1$) of the net-charge distributions, which can be related to volume independent susceptibility ratios, are studied as a function of centrality and energy. These quantities are important to understand the quantum-chromodynamics phase diagram and possible existence of a critical end point. The measured values are very well described by expectation from negative binomial distributions. We do not observe any nonmonotonic behavior in the ratios of the cumulants as a function of collision energy. The measured values of $C_1/C_2$ and $C_3/C_1$ can be directly compared to lattice quantum-chromodynamics calculations and thus allow extraction of both the chemical freeze-out temperature and the baryon chemical potential at each center-of-mass energy. The extracted baryon chemical potentials are in excellent agreement with a thermal-statistical analysis model.

• Received 30 June 2015

DOI:https://doi.org/10.1103/PhysRevC.93.011901