Search for Electric Quadrupole Moments in Nuclear Collisions with Finite Net Baryon Density

Abstract

It is predicted that a Chiral Magnetic Wave (CMW) at finite baryon density can induce an electric quadrupole moment in the quark-gluon plasma produced in heavy ion collisions [1]. This electric quadrupole deformation lifts the degeneracy between the elliptic flow (v2) of positive and negative pions leading to a greater elliptic flow for negative pions than that of positive pions. We study the difference between positive pion elliptic flow and negative pion elliptic flow measurements from STAR at RHIC for Gold+Gold collisions at p sNN = 39 GeV, and investigate the dependence of the elliptic flow difference on the measured net- charge asymmetry of the data sample. Here the elliptic flow difference is expected to be proportional to the net-charge asymmetry in the presence of an Electric Quadrupole Effect.