Background evaluations for the chiral magnetic effect with normalized correlators using a multiphase transport model

Abstract

The chiral magnetic effect (CME) induces an electric charge separation in a chiral medium along the magnetic field that is mostly produced by spectator protons in heavy-ion collisions. The experimental searches for the CME, based on the charge-dependent angular correlations ($\gamma$), however, have remained inconclusive, because the non-CME background contributions are not well understood. Experimentally, the $\gamma$ correlators have been measured with respect to the second-order (${\Psi }_2$) and the third-order (${\Psi }_3$) symmetry planes, defined as ${\gamma }_{112}$ and ${\gamma }_{123}$, respectively. The expectation was that with a proper normalization, ${\gamma }_{123}$ would provide a data-driven estimate for the background contributions in ${\gamma }_{112}$. In this work, we calculate different harmonics of the $\gamma$ correlators using a charge-conserving version of a multiphase transport (AMPT) model to examine the validity of the said assumption. We find that the pure-background AMPT simulations do not yield an equality in the normalized ${\gamma }_{112}$ and ${\gamma }_{123}$, quantified by ${\kappa }_{112}$ and ${\kappa }_{123}$, respectively. Furthermore, we test another correlator, ${\gamma }_{132}$, within AMPT, and discuss the relation between different $\gamma$ correlators.

arXiv comment8 pages, 6 figures

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Cited by in corpus (8)

• Further developments of a multi-phase transport model for relativistic nuclear collisions
• Signatures of Chiral Magnetic Effect in the Collisions of Isobars
• Constraining the Chiral Magnetic Effect with charge-dependent azimuthal correlations in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 and 5.02 TeV
• Utilization of Event Shape in Search of the Chiral Magnetic Effect in Heavy-ion Collisions
• Event Shape Selection Method in Search of the Chiral Magnetic Effect in Heavy-ion Collisions
• Search for the chiral magnetic effect through beam energy dependence of charge separation using event shape selection
• Experimental review on the chiral magnetic effect in relativistic heavy ion collisions
• Investigation of Experimental Observables in Search of the Chiral Magnetic Effect in Heavy-ion Collisions in the STAR experiment