Contact process with a defect: universal oasis, nonuniversal scaling

Abstract

The extinction transition in the presence of a localized quenched defect is studied numerically. When the bulk is at criticality, the correlation length diverges and even an infinite system cannot "decouple" from the defect. The results presented here suggest that, in 1+1 dimensions, the critical exponent $\delta$ that controls the asymptotic power-law decay depends on the strength of the local perturbation. On the other hand, the exponent was found to be independent of the local arrangement of the defect. In higher dimensions the defect seems to induce a transient behavior that decays algebraically in time.