title: Nonconcave entropies from generalized canonical ensembles.
abstract: It is well known that the entropy of the microcanonical ensemble cannot be calculated as the Legendre transform of the canonical free energy when the entropy is nonconcave. To circumvent this problem, a generalization of the canonical ensemble that allows for the calculation of nonconcave entropies was recently proposed. Here, we study the mean-field Curie-Weiss-Potts spin model and show, by direct calculations, that the nonconcave entropy of this model can be obtained by using a specific instance of the generalized canonical ensemble known as the Gaussian ensemble.
authors.affiliation: Max Planck Institute for Mathematics in the Sciences, Inselstrasse 22-26, 04103 Leipzig, Germany. marius.costeniuc@gmail.com
authors.forename: Marius
authors.initials: M
authors.lastname: Costeniuc
authors.forename: Richard S
authors.initials: RS
authors.lastname: Ellis
authors.forename: Hugo
authors.initials: H
authors.lastname: Touchette