Quantification of the Chiral Magnetic Effect in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV

TL;DR

This study uses transport and fluid dynamics models to quantify the chiral magnetic effect in Au+Au collisions at 200 GeV, finding a measurable CME signal that explains experimental charge separation data.

Contribution

It provides the first quantitative estimate of CME-driven charge separation in heavy-ion collisions using advanced models, linking experimental observables to CME signals.

Findings

CME signal estimated at approximately 0.5% in mid-central collisions.

Only about 25% of the charge separation signal is attributable to CME.

Predictions for CME detection in isobaric Ru+Ru and Zr+Zr collisions are presented.

Abstract

The Multi-Phase Transport model, AMPT, and the Anomalous Viscous Fluid Dynamics model, AVFD, are used to assess a possible chiral-magnetically-driven charge separation ($\Delta S$) recently measured with the ${R_{\Psi_2}(\Delta S)}$ correlator in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV. The Comparison of the experimental and simulated ${R_{\Psi_2}(\Delta S)}$ distributions indicates that background-driven charge separation is insufficient to account for the measurements. The AVFD model calculations, which explicitly account for CME-driven anomalous transport in the presence of background, indicate a CME signal quantified by the $P$-odd Fourier dipole coefficient ${a_1'}\approx 0.5\%$ in mid-central collisions. A similar evaluation for the $\Delta\gamma$ correlator suggests that only a small fraction of this signal ($f_{\rm CME}=\Delta\gamma_{\rm CME}/\Delta\gamma \approx 25\%$) is measurable with this correlator in the same collisions. The related prediction for signal detection in isobaric collisions of Ru+Ru and Zr+Zr are also presented.