Suppression of elliptic-flow-induced correlations in an observable of possible local parity violation

We show that fluctuations in elliptic anisotropy in heavy-ion collisions can be used to significantly reduce the contribution of transverse-momentum conservation, and of all background effects independent on the orientation of the reaction plane, from an observable of the chiral magnetic effect. We argue that for a given impact parameter, the magnetic field is approximately independent of the fluctuating shape of the fireball.