Critical behavior of a one-dimensional diffusive epidemic process - art. no. 066118

We investigate the critical behavior of a one-dimensional diffusive epidemi c propagation process by means of a Monte Carlo procedure. In the model, he althy (A) and sick (B) individuals diffuse on a lattice with diffusion cons tants D-A and D-B, respectively. According to a Wilson renormalization calc ulation, the system presents a second-order phase transition between a stea dy reactive state and a vacuum state, with distinct universality classes fo r the cases D-A=D-B and D-A<D-B. A first-order transition has been conjectu red for D-A>D-B. In this work we perform a finite size scaling analysis of order parameter data at the vicinity of the critical point in dimension d=1 . Our results show no signature of a first-order transition in the case of D-A >D-B. A finite size scaling typical of second-order phase transitions f its well the data from all three regimes. We found that the correlation exp onent nu =2 as predicted by field-theoretical arguments. Estimates for beta /nu are given for all relevant regimes.