It has recently been proposed that fluctuating "pulled" fronts propagating into an unstable state should not be in the standard Kardar-Parisi-Zhang (KPZ) universality class for rough interface... Show moreIt has recently been proposed that fluctuating "pulled" fronts propagating into an unstable state should not be in the standard Kardar-Parisi-Zhang (KPZ) universality class for rough interface growth. We introduce an effective field equation for this class of problems, and show on the basis of it that noisy pulled fronts in d+1 bulk dimensions should be in the universality class of the ((d+1)+1)D KPZ equation rather than of the (d+1)D KPZ equation. Our scenario ties together a number of heretofore unexplained observations in the literature, and is supported by previous numerical results. Show less
Saarloos, W. van; Tripathy, G.; Rocco, A.; Casademunt, J. 2001
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... Show moreWe 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 t600, these yield an effective exponent slightly larger than 1/4. Show less
