  We study the zero-frequency current noise of the interacting resonant level
model for arbitrary bias voltages using a functional renormalization group
approach. For this we extend the existing nonequilibrium scheme by deriving and
solving flow equations for the current-vertex functions. On-resonance
artificial divergences of the latter found in lowest-order perturbation theory
in the two-particle interaction are consistently removed. Away from resonance
they are shifted to higher orders. This allows us to gain a comprehensive
picture of the current noise in the scaling limit. At high bias voltages, the
current noise exhibits a universal power-law decay, whose exponent is to
leading order in the interaction identical to that of the current. The
effective charge on resonance is analyzed in detail employing properties of the
vertex correction. We find that it is only modified to second or higher order
in the two-particle interaction.
