Contact process with a defect: universal oasis, nonuniversal scaling

TL;DR

This study investigates how a localized defect affects the extinction transition in contact processes, revealing that critical exponents depend on defect strength in 1+1 dimensions and induce transient behaviors in higher dimensions.

Contribution

It provides numerical evidence that local defect strength influences critical exponents and transient dynamics in contact processes at extinction transitions.

Findings

Critical exponent δ depends on defect strength in 1+1 dimensions.

Exponent δ is independent of defect arrangement.

Defects induce algebraic decay in higher dimensions.

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.