Influence of quenched disorder on absorbing phase transitions

Sang Bug Lee (Kyungpook Natl. Univ.)

We review the recent works on absorbing phase transitions in the contact process and the even-offspring branching and annihilating random-walk, both with a spatial disorder. We then present recently published new results on the conserved lattice gas model on diluted lattices in two and three dimensions. According to the Harris criterion, the pure fixed point is unstable if dnu < 2, nu being the spatial correlation-length exponent for pure systems. Extensive simulations showed that, when the concentration of diluted sites is less than the critical concentration, the critical exponents were similar to those on a regular lattice both in two and three dimensions. On the other hand, when the concentration of disordered sites becomes critical, the density of active particles showed nonuniversal power-law behavior for all particle densities considered in both dimensions. These results were in contrast to the results for the diluted contact process, and the results in three dimensions were also contrasted to the prediction by the Harris criterion. The cause of nonuniversal behavior was addressed.