Universality of the contact process with random dilution

Abstract

We present quasi-stationary simulations of the two-dimensional contact process with quenched disorder included through the random dilution of a fraction of the lattice sites (these sites are not susceptible to infection). Our results strongly indicate that the static exponents are independent of the immunization fraction. In addition, the critical moment ratios $m=<\rho^2>/<\rho>^2$ deviate from the universal ratio $m=1.328$, observed for the non-dilluted system, to smaller values due to rare favorable regions which dominate the statistics.