One-body dynamics modified by collective fluctuations

Abstract

We show how the fluctuating part of the residual coupling between collective and intrinsic motion of a dissipative heavy-ion collision induces correlations in either subspace. They lead in general to a transport equation for the collective motion, and to a new term in the equation for the one-body density which describes collisions with the collective fluctuations. The resulting redistribution of the single-particle occupation numbers ρ_α and the evolution of the fluctuations are coupled with each other due to the dependence of the transition rates in the master equation on the fluctuations, and of the transport coefficients on ρ_α. Considering the special case of a long contact phase, we find the fluctuations to be most effective, with respect to a randomization of ρ_α, within a certain critical region where they pass from stable to unstable behaviour. Estimates are made for the corresponding relaxation times employing a schematic model.