From a colored glass condensate to the gluon plasma: Equilibration in highenergy heavy ion collisions - art. no. 024609

The initial distribution of gluons at the very early times after a high-ene rgy heavy ion collision is described by the bulk scale Q(s) of gluon satura tion in the nuclear wave function. The subsequent evolution of the system t owards kinetic equilibrium is described by a nonlinear Landau equation fur the single particle distributions [A. H. Mueller. Nucl. Phys. B572. 227 (20 00); Phys. Lett. B 475. 220 (2000)]. In this paper, we solve this equation numerically for the idealized initial conditions proposed by Mueller, and s tudy the evolution of the system to equilibrium. We discuss the sensitivity of our results on the dynamical screening of collinear divergences. In a p articular model of dynamical screening, the convergence to the hydrodynamic limit is seen to be rapid relative to hydrodynamic time scales. The equili bration time, the initial temperature, and the chemical potential are shown to have a strong functional dependence on the initial gluon saturation sca le Q(s).