Charge conservation in RHIC and contributiuons to local parity violation observables

Abstract

Relativistic heavy ion collisions provide laboratory environments from which one can study the creation of a novel state of matter, the quark gluon plasma. The existence of such a state is postulated to alter the mechanism and evolution of charge production, which then becomes manifest in charge correlations. We study the separation of balancing charges at kinetic freeze-out by analyzing recent result on balancing charge correlations for Au+Au collisions at $\sqrt{s_{NN}}=200 {GeV}$. We find that balancing charges are emitted from significantly smaller regions in central collisions compared to peripheral collisions. The results indicate that charge diffusion is small and that the centrality dependence points to a change of the production mechanism. In addition we calculate the contributions from charge-balance correlations to STAR's local parity violation observable. We find that local charge conservation, when combined with elliptic flow, explains much of STAR's measurement.