Free Streaming and Hydrodynamic Simulations of Heavy Nucleus Collisions at RHIC

While providing excellent predictions for low p? particle spectra and transverse radial and elliptic ow, hydrodynamic simulations of heavy nucleus collisions have disagreed with recent data on the HBT radii calculated from the collisions of Au+Au at p s = 130 AGeV at RHIC. A novel initialization developed here to investigate the possibilities of new physics evolves the system through the process of free streaming in the preequilibrium phase ( < eq). An elementary discussion of hydrodynamics, kinetic freeze-out, and HBT analysis is given, as well as the matching conditions of the free streaming initialization to the hydrodynamic evolution. Subsequent results show that for this type of initialization, freeze-out occurs approximately 13% faster with a 13% larger transverse radius. These results are better correlated with RHIC data and suggest implementation of intitial free streaming may provide a reasonable approximation to the early non-equilibrium stage of the collision.