Title: Charge Asymmetry Dependence of Pion/Kaon Azimuthal Anisotropy in Heavy Ion Collisions at STAR
Abstract: Theoretical studies indicate that in relativistic heavy collisions a chiral magnetic wave at finite baryon density could induce an electric quadrupole moment, which will lead to a difference in elliptic flow of hadrons with opposite charge. The magnitude of this difference is predicted to be proportional to the charge asymmetry Ach, which is defined as the ratio of net charge and total multiplicity.
> In this talk, we present STAR’s measurement of π- and π+ elliptic flow, v2, at midrapidity in Au+Au collisions at √sNN = 200, 62.4, 39, 27, 19.6, 11.5 and 7.7 GeV, as a function of Ach. We find that π- (π+) elliptic flow linearly increases (decreases) with charge asymmetry for most centrality bins at √sNN = 27 GeV and higher. The slope of the difference of v2 between π- and π+ shows similar centrality dependence from 200 to 27 GeV and it is qualitatively consistent to the calculations that incorporate a chiral magnetic wave effect at √sNN = 200 GeV. The similar phenomenal is also be observed in U+U collisions at √sNN = 193 GeV. The slopes from Kaons and v3 difference are also been checked to compare with different theoretical arguments.
HEP May19 flyer