Two- and three-particle nonflow contributions to the chiral magnetic effect measurement by spectator and participant planes in relativistic heavy ion collisions

TL;DR

This study assesses how two- and three-particle nonflow correlations influence the measurement of the chiral magnetic effect in relativistic heavy ion collisions, using models and experimental data to quantify these effects.

Contribution

It provides a detailed analysis of nonflow contributions to CME measurements, highlighting their magnitude and impact on experimental results.

Findings

Nonflow effects are approximately 4% without pseudorapidity gaps.

Nonflow effects are approximately -5% with pseudorapidity gaps.

Nonflow contributions are significant in centrality 20-50% Au+Au collisions at 200 GeV.

Abstract

Correlation measurements with respect to the spectator and participant planes in relativistic heavy ion collisions were proposed to extract the chiral magnetic effect (CME) from background dominated azimuthal correlators. This paper investigates the effects of two- and three-particle nonflow correlations on the extracted CME signal fraction, $f_{\text{CME}}$. It is found, guided by a multiphase transport (AMPT) model and the heavy ion jet interaction generator (HIJING) together with experimental data, that the nonflow effects amount to approximately $(4\pm5)$% and $(-5\pm3)$% without and with pseudorapidity gaps, respectively, in 20-50% centrality Au+Au collisions at $\sqrt{s_{\text{NN}}}= 200 \text{ GeV}$.