Measurement of higher cumulants of net-charge multiplicity distributions in Au + Au collisions at = 7.7-200 GeV

=7.7-200GeVでの金-金衝突における正味の電荷多重度分布の高次累積度の測定

Adare, A.*; 今井 憲一; 永宮 正治; 佐甲 博之   ; 佐藤 進  ; 谷田 聖   ; PHENIX Collaboration*; 他506名*

Adare, A.*; Imai, Kenichi; Nagamiya, Shoji; Sako, Hiroyuki; Sato, Susumu; Tanida, Kiyoshi; PHENIX Collaboration*; 506 of others*

We report the measurement of cumulants (, ) of the net-charge distributions measured within pseudorapidity () in Au + Au collisions at = 7.7-200 GeV with the PHENIX experiment at the Relativistic Heavy Ion Collider. The ratios of cumulants (e.g., , ) 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 and 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.