Long-range charge fluctuations and search for a quark-gluon plasma signal - art. no. 064903

We critically discuss a recent suggestion to use long-range modes of charge (electric or baryon) fluctuations as a signal for the presence of quark-gl uon plasma at the early stages of a heavy ion collision. We evaluate the ra te of diffusion in rapidity for different secondaries, and argue that for c onditions of the Super Proton Synchrotron (SPS) experiments, it is strong e nough to relax the magnitude of those fluctuations almost to its equilibriu m values, given by hadronic "resonance gas." We evaluate the detector accep tance needed to measure such "primordial'' long-range fluctuations at Relat ivistic Heavy Ion Collider (RHIC) conditions. We conclude with an applicati on of the charge fluctuation analysis to the search for the QCD critical po int.