Search for Chiral Magnetic Effects in High-Energy Nuclear Collisions

Abstract

We present measurements of pion elliptic flow ($v_2$) in Au+Au collisions at $\sNN =$ 200, 62.4, 39, 27 and 19.6 GeV, as a function of event-by-event charge asymmetry ($A_{\pm}$), based on data from the STAR experiment at RHIC. We find that $π^-$ ($π^+$) elliptic flow linearly increases (decreases) with charge asymmetry for most centrality bins and for all the beam energies under study. The slope parameter ($r$) from $v_2(A_\pm)$ difference between $π^-$ and $π^+$ shows a centrality dependency similar with the calculations with Chiral Magnetic Wave. The measurements of charge separation with respect to the reaction plane in search of Local Parity Violation and Chiral Magnetic Effect are also presented for Au+Au collisions at $\sNN =$ 200, 62.4, 39, 27, 19.6, 11.5 and 7.7 GeV, and for U+U collisions at 193 GeV.