The decoupling problem at RHIC

We investigate whether it is possible to dynamically generate from classical transport theory the observed surprising R_out ≈ R_side in Au+Au at (sqrt s = 130A) GeV at RHIC [1,2]. We obtained covariant solutions to the Boltzmann transport equation via the MPC technique [3], for a wide range of partonic initial conditions and opacities. We demonstrate that there exist transport solutions that yield a freezeout distribution with R _out < R _side for K _⊥ ? 1.5 GeV. These solutions correspond to continuous evaporation-like freezeout, where the emission duration is comparable to the source size. Naively this would mean R _out > R _side. Nevertheless, our sources exhibit R _out < R _side because they are narrower in the‘out’ than in the‘side’ direction and, in addition, a positive x _out-t correlation develops reducing R _out further.