Absorbing-state phase transitions in fixed-energy sandpiles
Alessandro Vespignani, Ronald Dickman, Miguel A. Munoz, Stefano Zapperi
Abstract
We study sandpile models as closed systems, with conserved energy density
ζ
playing the role of an external parameter. The critical energy density,
ζ
c
, marks a nonequilibrium phase transition between active and absorbing states. Several fixed-energy sandpiles are studied in extensive simulations of stationary and transient properties, as well as the dynamics of roughening in an interface-height representation. Our primary goal is to identify the universality classes of such models, in hopes of assessing the validity of two recently proposed approaches to sandpiles: a phenomenological continuum Langevin description with absorbing states, and a mapping to driven interface dynamics in random media. Our results strongly suggest that there are at least three distinct universality classes for sandpiles.