Epidemic dynamics of two species of interacting particles on scale-free networks.

We study the nonequilibrium phase transition in a model for epidemic spreading on scale-free networks. The model consists of two particle species A and B, and the coupling between them is taken to be asymmetric; A induces B while B suppresses A. This model describes the spreading of an epidemic on networks equipped with a reactive immune system. We present analytic results on the phase diagram and the critical behavior, which depends on the degree exponent gamma of the underlying scale-free networks. Numerical simulation results that support the analytic results are also presented.