Extracting the chemistry and diffusivity of the QGP with charge balance functions

One of the first questions people ask us about heavy-ion physics at ultra-relativistic energies is "What evidence do you have for early (first fm/c) chemical equilibrium of the QGP?". I will show how this question can be definitively addressed by charge balance correlations. Early creation of quark-antiquark pairs should lead to large separations of balancing charges, particularly strangeness and baryon charge, along the beam axis. Indeed, such large separations have been observed by STAR and ALICE, and are consistent with the model calculations I will present here, which are based on local chemical equilibrium. Further, if the light-quark diffusivity is small, separation of the same charges in azimuthal angle should be narrow. Again, the same calculation appears consistent with recent measurement, and by assuming a diffusivity of the form calculated by lattice gauge theory. I will provide a list of calculations, measurements and analyses that will be able to quantitatively address these questions.