Absorbing Phase Transitions
Roberto Livi, Paolo Politi
Abstract
Absorbing phase transitions are an important class of nonequilibrium phase transitions. They are characterized by one or more absorbing states, defined as microscopic states from which the system cannot escape. The most famous case with one absorbing state is called directed percolation (a sort of driven version of the usual, isotropic percolation) and it represents, for example, the spreading of a disease through a contact process: If the infection rate is large enough with respect to the recovery rate, the asymptotic state shows a finite fraction of infected individuals. Models with one absorbing state, local dynamics, and no additional symmetries typically fall within the directed percolation universality class. We also provide a short introduction to self-organized criticality, devoting a section to the Bak–Tang–Wiesenfeld model.