Interface depinning versus absorbing-state phase transitions.

According to recent numerical results from lattice models, the critical exponents of systems with many absorbing states and order parameter coupled to a nondiffusive conserved field coincide with those of the linear interface depinning model within computational accuracy. In this paper the connection between absorbing-state phase transitions and interface pinning in quenched disordered media is investigated. For that, we present an heuristic mapping of the interface dynamics in a disordered medium into a Langevin equation for the active-site density and show that a Reggeon-field-theory-like description, in which the order parameter appears coupled to an additional nondiffusive conserved field, emerges rather naturally. Reciprocally, we construct a mapping from a discrete model belonging in the absorbing state with a conserved-field class to a discrete interface equation, and show how a quenched disorder, typical of the interface representation is originated. We discuss the character of the possible noise terms in both representations, and overview the critical exponent relations. Evidence is provided that, at least for dimensions larger that one, both universality classes are just two different representations of the same underlying physics.