title: Thermodynamics of Nonadditive Systems.
abstract: The usual formulation of thermodynamics is based on the additivity of macroscopic systems. However, there are numerous examples of macroscopic systems that are not additive, due to the long-range character of the interaction among the constituents. We present here an approach in which nonadditive systems can be described within a purely thermodynamics formalism. The basic concept is to consider a large ensemble of replicas of the system where the standard formulation of thermodynamics can be naturally applied and the properties of a single system can be consequently inferred. After presenting the approach, we show its implementation in systems where the interaction decays as 1/r(α) in the interparticle distance r, with α smaller than the embedding dimension d, and in the Thirring model for gravitational systems.
authors.affiliation: Departament de Física Fonamental, Facultat de Física, Universitat de Barcelona, Martí i Franqués 1, 08028 Barcelona, Spain.
authors.forename: Ivan
authors.initials: I
authors.lastname: Latella
authors.affiliation: Departament de Física Fonamental, Facultat de Física, Universitat de Barcelona, Martí i Franqués 1, 08028 Barcelona, Spain.
authors.forename: Agustín
authors.initials: A
authors.lastname: Pérez-Madrid
authors.affiliation: Complex Systems and Theoretical Physics Unit, Health and Technology Department, Istituto Superiore di Sanità, and INFN Roma 1, Gruppo Collegato Sanità, Viale Regina Elena 299, 00161 Roma, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Campa
authors.affiliation: Dipartimento di Fisica e Astronomia and CSDC, Università di Firenze, and INFN, Sezione di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino (FI), Italy.|INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy.
authors.forename: Lapo
authors.initials: L
authors.lastname: Casetti
authors.affiliation: Dipartimento di Fisica e Astronomia and CSDC, Università di Firenze, and INFN, Sezione di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino (FI), Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Ruffo