Effects of final state interactions on charge separation in relativistic heavy ion collisions

Abstract

Charge separation is an important consequence of the Chiral Magnetic Effect. Within the framework of a multi-phase transport model, the effects of final state interactions on initial charge separation are studied. We demonstrate that charge separation can be significantly reduced by the evolution of the Quark-Gluon Plasma produced in relativistic heavy ion collisions. Hadronization and resonance decay can also affect charge separation. Moreover, our results show that the Chiral Magnetic Effect leads to the modification of the relation between the charge azimuthal correlation and the elliptic flow that is expected from transverse momentum conservation only. The transverse momentum and pseudorapidity dependences of, and the effects of background on the charge azimuthal correlation are also discussed.

Measurement of charge multiplicity asymmetry correlations in high-energy nucleus-nucleus collisions atsNN=200GeV

“…The AMPT model is a useful tool for this study because it can mostly reproduce elliptic flow data, it includes decays of resonances possessing anisotropic flow, and it should contain correlations caused by momentum and local charge conservations. The AMPT results indeed show a linear dependence between the same-sign charge correlations and the elliptic anisotropy [41], qualitatively consistent with data. It is possible that the linear dependence observed in AMPT is due to the net effect of elliptic anisotropy and a difference between the same-and opposite-sign charged particle correlations [28,29].…”

“…The weaker dependence of the opposite-sign correlation on event anisotropy may be the net effect of two competing mechanisms of momentum and local charge conservations. Charge correlations as a function of elliptic anisotropy have also been studied in a multi-phase transport (AMPT) model [41], motivated by phenomenological studies [28,29,39] and the preliminary version of the data reported here. The AMPT model is a useful tool for this study because it can mostly reproduce elliptic flow data, it includes decays of resonances possessing anisotropic flow, and it should contain correlations caused by momentum and local charge conservations.…”

Electromagnetic fields and anomalous transports in heavy-ion collisions—a pedagogical review

“…The TMC always gives negative contributions to both γ and δ, and it becomes more important for more peripheral collisions because the multiplicity decreases and v 2 increases as the centrality decreases. The TMC can give a large amount of contribution to γ αβ and δ αβ as shown by AMPT simulation [230,237] (This can also be roughly estimated by choosing v 2 ∼ 0.1 and N ∼ 1000 for moderate centrality bins at RHIC which gives γ TMC ∼ 10 −4 and δ TMC ∼ 10 −3 being at the same order of magnitude as the STAR results [211,212]). In order to evidence the contributions of CME, it is useful to subtract the TMC contribution from γ.…”

Charge separation with fluctuating domains in relativistic heavy-ion collisions

“…So far these experimental measurements of cos(φ α ± φ β ) are qualitatively consistent with the CME expectations. Recently, a multiphase transport (AMPT) model was implemented to study charge azimuthal correlations by introducing an initial electric charge dipole distribution, which discloses that final state interactions can play a significant role in weakening the initial charge separation in Au+Au collisions at the top RHIC energy [13]. An A ch -dependent charge asymmetry of pion elliptic flow is also reproduced by introducing an initial electric charge quadrupole distribution, which provides a helpful constraint to the quadrupole effect from the chiral magnetic wave [14].…”

“…Nevertheless, no real dynamical scenario of metastable domains were taken into account in Ref. [13], because the imported dipole charge separation was assumed to be randomly distributed in the global fireball. In this work, we introduce initial separated charges located inside many P-or CP-odd bubbles, then some useful information about the properties of metastable domains is extracted by comparing charge azimuth angle correlations between the model and the experimental data.…”