Study of the Background in Search for the Chiral Magnetic Effect in Heavy-Ion Collisions with the AMPT Model

The chiral magnetic effect (CME) arises from the chirality imbalance of quarks and its interaction to the strong magnetic field generated in non-central heavy-ion collisions. Possible formation of domains of quarks with chirality imbalances is an intrinsic property of the Quantum ChromoDynamics (QCD), which describes the fundamental strong interactions among quarks and gluons. Azimuthal-angle correlations have been used to measure the magnitude of charge-separation across the reaction plane, which was predicted to arise from the CME [1]. However, backgrounds from collective motion (flow) of the collision system can also contribute to the correlation observable. In this poster, we investigate the magnitude of the background utilizing the AMPT model [2], which contains no CME signals. We calculate the charge-separation observables and the background correlations in Au+Au collisions at 200 GeV and U+U collisions at 193 GeV, which provides a background baseline for the experimental data.

[1] D. E. Kharzeev, L. D. McLerran and H. J. Warringa, Nucl. Phys. A 803, 227 (2008).
[2] Z.W. Lin and C.M. Ko, Phys. Rev. C 65, 034904 (2002).