Asymptotic scaling of the diffusion coefficient of fluctuating "pulled" fronts.

We present a (heuristic) theoretical derivation for the scaling of the diffusion coefficient D(f) for fluctuating "pulled" fronts. In agreement with earlier numerical simulations, we find that as N--> infinity, D(f) approaches zero as 1/ln(3) N, where N is the average number of particles per correlation volume in the stable phase of the front. This behavior of D(f) stems from the shape fluctuations at the very tip of the front, and is independent of the microscopic model.