PHASE TRANSITION FOR A NOISE-DRIVEN MODEL COUPLED BY A MEAN FIELD

We report a new model for infinite interacting noise driven subsystems which are coupled by a mean field and study its nonequilibrium phase transitions. In this model, under some circumstances the phase transition is between the state with zero mean field and the state with non zero mean field, and has a breaking of symmetry, which is similar to that reported by Van den Broeck, Parrondo, Toral, and Armcro Phys. Rev. Lett.,73(1994),3395; Phys. Rev., E49(1994),2639], by Pikovsky, Rateitschak, and Kurths Z.Phys.,B95(1994),541], and by other authors. We style this nonequi librium phase transition the symmetry breaking mean field. However, under other circumstances, the nonequilibrium phase transition of our model is not of the symme try breaking mean field type, which is a new phenomenon that has not been reported before.