  An analytical description of non-equilibrium phenomena in interacting quantum
systems is rarely possible. Here we present one example where such a
description can be achieved, namely the ferromagnetic Kondo model. In
equilibrium, this model is tractable via perturbative renormalization-group
techniques. We employ a recently developed extension of the flow-equation
method to calculate the non-equilibrium decay of the local magnetization at
zero temperature. The flow equations admit analytical solutions which become
exact at short and long times, in the latter case revealing that the system
always retains a memory of its initial state.
