Revisit the Chiral Magnetic Effect Expectation in Isobaric Collisions at the Relativistic Heavy Ion Collider

Abstract

Isobaric ${}_{44}^{96}$Ru+${}_{44}^{96}$Ru and ${}_{40}^{96}$Zr+${}_{40}^{96}$Zr collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV have been conducted at the Relativistic Heavy Ion Collider to circumvent the large flow-induced background in searching for the chiral magnetic effect (CME), predicted by the topological feature of quantum chromodynamics (QCD). Considering that the background in isobar collisions is approximately twice that in Au+Au collisions (due to the smaller multiplicity) and the CME signal is approximately half (due to the weaker magnetic field), we caution that the CME may not be detectable with the collected isobar data statistics, within $\sim$2$\sigma$ significance, if the axial charge per entropy density ($n_5/s$) and the QCD vacuum transition probability are system independent. This expectation is generally verified by the Anomalous-Viscous Fluid Dynamics (AVFD) model. While our estimate provides an approximate "experimental" baseline, theoretical uncertainties on the CME remain large.

6 pages, 1 multi-panel figure. v2: version after addressing referee comments. Corrected a factor 2 error in the quoted multiplicity; corrected a factor 2 error in the A-dependence exponent of the magnetic field; conclusions unchanged. v3: match published version

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Cited by in corpus (10)

• The Present and Future of QCD
• Implications of the isobar run results for chiral magnetic effect in heavy ion collisions
• Chiral Magnetic Effect in Heavy Ion Collisions: The Present and Future
• Two- and three-particle nonflow contributions to the chiral magnetic effect measurement by spectator and participant planes in relativistic heavy ion collisions
• Utilization of Event Shape in Search of the Chiral Magnetic Effect in Heavy-ion Collisions
• Estimate of Background Baseline and Upper Limit on the Chiral Magnetic Effect in Isobar Collisions at $\sqrt{s_{\text{NN}}}=200$ GeV at the Relativistic Heavy-Ion Collider
• Search for the chiral magnetic wave using anisotropic flow of identified particles at RHIC
• Difference between signal and background of the chiral magnetic effect relative to spectator and participant planes in isobar collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=200$ GeV
• Collective Excitation in High-Energy Nuclear Collisions -- In Memory of Professor Lianshou Liu
• Experimental review on the chiral magnetic effect in relativistic heavy ion collisions