title: Stability and ensemble inequivalence in a globally coupled system.
abstract: We consider a system of globally coupled rotors, described by a set of Langevin equations, and examine the stability of the incoherent phase. The corresponding Fokker-Planck equation, providing a unified description of microcanonical and canonical ensembles, bears a few solutions, depending upon the ensemble. It is found that the stability of each solution varies differently with the temperature, revealing the inequivalence between the two ensembles. This also suggests a physical explanation of the quasistationarity observed in recent numerical results.
authors.affiliation: Department of Physics, Seoul National University, Seoul 151-747, Korea.
authors.forename: M Y
authors.initials: MY
authors.lastname: Choi
authors.forename: J
authors.initials: J
authors.lastname: Choi