Search for the Chiral Magnetic Wave with Anisotropic Flow of Identified Particles at RHIC-STAR

Abstract

The chiral magnetic wave (CMW) has been theorized to propagate in the Quark-Gluon Plasma formed in high-energy heavy-ion collisions. It could cause a finite electric quadrupole moment of the collision system, and may be observed as a dependence of elliptic flow, v2, on the asymmetry between positively and negatively charged hadrons, Ach. However, non-CMW mechanisms, such as local charge conservation (LCC) and hydrodynamics with isospin effect, could also contribute to the experimental observations. Here we present the STAR measurements of elliptic flow v2 and triangular flow v3 of charged pions, along with v2 of charged kaons and protons, as functions of Ach in Au+Au collisions at sNN=200GeV. The slope parameters of Δv2(Ach) and Δv3(Ach) are reported and compared to investigate the LCC background. The similarity between pion and kaon slopes suggests that the hydrodynamics is not the dominant mechanism. The difference between the normalized Δv2 and Δv3 slopes, together with the small slopes in p+Au and d+Au collisions at sNN=200GeV, suggest that the CMW picture remains a viable interpretation at RHIC.