Systems with long-range interactions display a short-time relaxation towards quasistationary states whose lifetime increases with system size. With reference to the Hamiltonian mean field model, we here show that a maximum entropy principle, based on Lynden-Bell’s pioneering idea of “violent relaxation,” predicts the presence of out-of-equilibrium phase transitions separating the relaxation towards homogeneous (zero magnetization) or inhomogeneous (nonzero magnetization) quasistationary states. When varying the initial condition within a family of “water bags” with different initial magnetization and energy, first- and second-order phase transition lines are found that merge at an out-of-equilibrium tricritical point. Metastability is theoretically predicted and numerically checked around the first-order phase transition line.
|Titolo:||Nonequilibrium tricritical point in a system with long-range interactions|
|Autori:||A. Antoniazzi; D. Fanelli; S. Ruffo; Y. Y. Yamaguchi|
|Rivista:||PHYSICAL REVIEW LETTERS|
|Data di pubblicazione:||2007|
|Digital Object Identifier (DOI):||10.1103/PhysRevLett.99.040601|
|Appare nelle tipologie:||1.1 Journal article|