Subdiffusive Activity Spreading in the Diffusive Epidemic Process

TL;DR

This paper investigates the critical dynamics of the diffusive epidemic process, revealing subdiffusive infection spread and diffusive healthy fluctuations, which enhances understanding of its phase transition behavior.

Contribution

It uncovers two distinct processes at criticality—subdiffusive infection spreading and diffusive healthy fluctuations—using simulations and finite-size scaling analysis.

Findings

Infection clusters spread subdiffusively at criticality

Healthy population fluctuations are diffusive

Identifies a strong-coupling regime in the system

Abstract

The diffusive epidemic process is a paradigmatic example of an absorbing state phase transition in which healthy and infected individuals spread with different diffusion constants. Using stochastic activity spreading simulations in combination with finite-size scaling analyses we reveal two qualitatively different processes that characterize the critical dynamics: subdiffusive propagation of infection clusters and diffusive fluctuations in the healthy population. This suggests the presence of a strong-coupling regime and sheds new light on a longstanding debate about the theoretical classification of the system.