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Equilibrium states and entropy theory for Nica-Pimsner algebras

Lookup NU author(s): Dr Evgenios Kakariadis



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


© 2019. We study the equilibrium simplex of Nica-Pimsner algebras arising from product systems of finite rank on the free abelian semigroup. First we show that every equilibrium state has a convex decomposition into parts parametrized by ideals on the unit hypercube. Secondly we associate every gauge-invariant part to a sub-simplex of tracial states of the diagonal algebra. We show how this parametrization lifts to the full equilibrium simplices of non-infinite type. The finite rank entails an entropy theory for identifying the two critical inverse temperatures: (a) the least upper bound for existence of non finite-type equilibrium states, and (b) the least positive inverse temperature below which there are no equilibrium states at all. We show that the first one can be at most the strong entropy of the product system whereas the second is the infimum of the tracial entropies (modulo negative values). Thus phase transitions can happen only in-between these two critical points and possibly at zero temperature.

Publication metadata

Author(s): Kakariadis ETA

Publication type: Article

Publication status: Published

Journal: Advances in Mathematics

Year: 2020

Volume: 362

Print publication date: 04/03/2020

Online publication date: 27/12/2019

Acceptance date: 28/11/2019

Date deposited: 28/11/2019

ISSN (print): 0001-8708

ISSN (electronic): 1090-2082

Publisher: Academic Press Inc.


DOI: 10.1016/j.aim.2019.106940


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