Directed Percolation and Systems with Absorbing States: Impact of Boundaries

We review the critical behavior of nonequilibrium systems, such as directed percolation (DP) and branching-annihilating random walks (BARW), which possess phase transitions into absorbing states. After reviewing the bulk scaling behavior of these models, we devote the main part of this review to analyzing the impact of walls on their critical behavior. We discuss the possible boundary universality classes for the DP and BARW models, which can be described by a general scaling theory which allows for two independent surface exponents in addition to the bulk critical exponents. Above the upper critical dimension $d_c$, we review the use of mean field theories, whereas in the regime $d
Comment: 37 pages (including figures); journal-ref + ref added