Universal interface fluctuations in the contact process

Abstract

We study the interface representation of the contact process (CP) at its directed-percolation critical point, where the scaling properties of the interface can be related to those of the original particle model. Interestingly, such a behavior happens to be intrinsically anomalous and more complex than that described by the standard Family-Vicsek dynamic scaling Ansatz of surface kinetic roughening. We expand on a previous numerical study by Dickman and Mu\~noz [Phys. Rev. E 62, 7632 (2000)] to fully characterize the kinetic roughening universality class for interface dimensions $d=1, 2$, and 3. Beyond obtaining scaling exponent values, we characterize the interface fluctuations via their probability density function (PDF) and covariance, seen to display universal properties which are qualitatively similar to those recently assessed for the Kardar-Parisi-Zhang (KPZ) and other important universality classes of kinetic roughening. Quantitatively, while for $d=1$ the interface covariance seems to be well described by the KPZ, Airy$_1$ covariance, no such agreement occurs in terms of the fluctuation PDF nor the scaling exponents.