Diffusion may obliterate fluctuation signals of the QCD phase transition in nuclear collisions at SPS and RHIC energies. We propose a hyperbolic diffusion equation to study the dissipation of net charge fluctuations. This equation is needed in a relativistic context, because the classic parabolic diffusion equation violates causality. We find that causality substantially limits the extent to which diffusion can dissipate these fluctuations.
In addition to net charge fluctuations we are also concerned with the transverse momentum fluctuations and how is it related to the onset of thermalization in nuclear collisions. We propose a new approach to incorporate radial flow and jet quenching effects to this thermalization picture. We find that for AuAu collisions at RHIC the jet or flow can explain the p t fluctuations in the most central collisions.
