Subdiffusive fluctuations of "pulled" fronts with multiplicative noise
We study the propagation of a "pulled" front with multiplicative noise that is created by a local perturbation of an unstable state. Unlike a front propagating into a metastable state, where a separation of time scales for sufficiently large t creates a diffusive wandering of the front position about its mean, we predict that for so-called pulled fronts, the fluctuations are subdiffusive with root mean square wandering Delta(t) approximately t(1/4), not t(1/2). The subdiffusive behavior is confirmed by numerical simulations: For t</=600, these yield an effective exponent slightly larger than 1/4.
Rocco
A
Departament ECM, Facultat de Fisica, Universitat de Barcelona, Avenida Diagonal 647, E-08028 Barcelona, Spain.
Ebert
U
Saarloos
W