SpecialitySISSA, Trieste, IT

Statistical mechanics of non additive systemsThe standard formulation of thermodynamics relies on additivity. However, there are numerous examples of macroscopic systems that are non additive, due to long-range interactions among the constituents. These systems can attain equilibrium states under completely open conditions, for which energy, volume and number of particles simultaneously fluctuate. The unconstrained ensemble is the statistical ensemble describing completely open systems; temperature, pressure and chemical potential constitute a set of independent control parameters, thus violating Gibbs-Duhem relation.We illustrate the properties of this ensemble by considering a modified version of Thirring model with both attractive and repulsive long-range interactions and we compare the results with those in other ensembles. This work contributes to the understanding of long-range interacting systems exchanging heat, work and matter with the environment