  Charge balance functions reflect the evolution of charged pair correlations
throughout the stages of pair production, dynamical diffusion, and
hadronization in heavy-ion collisions. Microscopic modeling of these
correlations in the full collision volume shows that the balance functions are
sensitive to the diffusivity of light quarks when studied as functions of
relative azimuthal angle. By restricting our analysis to K+,K- and p,pbar
pairs, we find that the diffusivity of light quarks, a fundamental property not
currently well understood, can be constrained by experimental measurement.
