Nonuniversal Critical Spreading in Two Dimensions

TL;DR

This paper investigates a two-dimensional nonequilibrium model with many absorbing states, revealing nonuniversal critical exponents that vary with initial conditions, challenging traditional universality assumptions.

Contribution

It demonstrates that critical spreading exponents in this model are nonuniversal and depend on initial density, providing new insights into phase transition behavior.

Findings

Critical exponents delta and eta vary with initial density phi.

The critical point location depends on phi.

Static behavior belongs to directed percolation universality class.

Abstract

Continuous phase transitions are studied in a two dimensional nonequilibrium model with an infinite number of absorbing configurations. Spreading from a localized source is characterized by nonuniversal critical exponents, which vary continuously with the density phi in the surrounding region. The exponent delta changes by more than an order of magnitude, and eta changes sign. The location of the critical point also depends on phi, which has important implications for scaling. As expected on the basis of universality, the static critical behavior belongs to the directed percolation class.