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We complete the analysis of KMS-states of the Toeplitz algebra of the affine semigroup over the natural numbers, recently studied by Raeburn and the first author, by showing that for every inverse temperature beta in the critical interval…

Operator Algebras · Mathematics 2010-10-05 Marcelo Laca , Sergey Neshveyev

We give a notion of quantum automorphism group of graph C*-algebras without sink at critical inverse temperature. This is defined to be the universal object of a category of CQG's having a linear action in the sense of [11] and preserving…

Operator Algebras · Mathematics 2020-08-20 Arnab Mandal , Soumalya Joardar

We investigate KMS states of Fowler's Nica-Toeplitz algebra $\mathcal{NT}(X)$ associated to a compactly aligned product system $X$ over a semigroup $P$ of Hilbert bimodules. This analysis relies on restrictions of these states to the core…

Operator Algebras · Mathematics 2012-07-18 Jeong Hee Hong , Nadia S. Larsen , Wojciech Szymański

The paper contains a description of the KMS states and ground states of a generalized gauge action on the C*-algebra of a finite graph.

Operator Algebras · Mathematics 2015-05-19 J. Christensen , K. Thomsen

We consider the dynamics of systems of lattice bosons with infinitely many degrees of freedom. We show that their dynamics defines a group of automorphisms on a $C^*$--algebra introduced by Buchholz, which extends the resolvent algebra of…

Mathematical Physics · Physics 2025-06-13 Andreas Deuchert , Jonas Lampart , Marius Lemm

We study some relations between self-similar group actions and operator algebras. We consider KMS states on the Cuntz--Pimsner algebras constructed by Nekrashevych from self-similar actions and the GNS representations of the KMS states. The…

Operator Algebras · Mathematics 2020-02-04 Keisuke Yoshida

We study the generalised Bunce-Deddens algebras and their Toeplitz extensions constructed by Kribs and Solel from a directed graph and a sequence $\omega$ of positive integers. We describe both of these $C^*$-algebras in terms of novel…

Operator Algebras · Mathematics 2015-10-14 David Robertson , James Rout , Aidan Sims

We study the high-temperature equilibrium for the C*-algebra $\mathcal T (\mathbb N^\times \ltimes \mathbb N)$ recently considered by an Huef, Laca and Raeburn. We show that the simplex of KMS$_\beta$ states at each inverse temperature…

Operator Algebras · Mathematics 2025-10-09 Marcelo Laca , Tyler Schulz

The paper contains a description of the KMS weights for the one-parameter action on the reduced C*-algebra of a second countable locally compact Hausdorff etale groupoid, arising from a continuous real valued homomorphism satisfying two…

Operator Algebras · Mathematics 2013-06-24 Klaus Thomsen

We describe KMS and ground states arising from a generalized gauge action on ultragraph C*-algebras. We focus on ultragraphs that satisfy Condition~(RFUM), so that we can use the partial crossed product description of ultragraph C*-algebras…

Operator Algebras · Mathematics 2019-09-11 Gilles Gonçalves de Castro , Daniel Gonçalves

We present a class of subshifts $Z_N, N = 1,2,...$ whose associated $C^*$-algebras ${\cal O}_{Z_N}$ are simple, purely infinite and not stably isomorphic to any Cuntz-Krieger algebra nor to Cuntz algebra. The class of the subshifts is the…

Operator Algebras · Mathematics 2008-05-20 Kengo Matsumoto

We characterize the state space of a Toeplitz-Cuntz algebra TO_n in terms of positive operator matrices $\Omega$ on Fock space which satisfy sl(\Omega) \le \Omega, where sl(\Omega) is the operator matrix obtained from \Omega by taking the…

funct-an · Mathematics 2008-02-03 Neal J. Fowler

The Kubo-Martin-Schwinger condition is a widely studied fundamental property in quantum statistical mechanics which characterises the thermal equilibrium states of quantum systems. In the seventies, G. Gallavotti and E. Verboven, proposed…

Mathematical Physics · Physics 2019-04-22 Z. Ammari , A. Ratsimanetrimanana

We present a detailed exposition (for a Dynamical System audience) of the content of the paper: R. Exel and A. Lopes, $C^*$ Algebras, approximately proper equivalence relations and Thermodynamic Formalism, {\it Erg. Theo. and Dyn. Syst.},…

Dynamical Systems · Mathematics 2021-10-14 Ruy Exel , Artur O. Lopes

We investigate how the fixed point algebra of a C*-dynamical system can differ from the underlying C*-algebra. For any exact group $\Gamma$ and any infinite group $\Lambda$, we construct an outer action of $\Lambda$ on the Cuntz algebra…

Operator Algebras · Mathematics 2020-12-09 Yuhei Suzuki

Let $\varphi:X\to X$ be a homeomorphism of a compact metric space $X$. For any continuous function $F:X\to \mathbb{R}$ there is a one-parameter group $\alpha^{F}$ of automorphisms on the crossed product $C^*$-algebra…

Operator Algebras · Mathematics 2021-04-20 Johannes Christensen , Klaus Thomsen

In this paper, we consider a generalized Toeplitz algebra $\mathcal{T} ( \mathrm{P}\rtimes\Bbb N^{\times})$ for a non-quasi-lattice ordered semigroup $ \mathrm{P}\rtimes\Bbb N^{\times}$ where $ \mathrm{P}\rtimes\Bbb N^{\times}$ is a…

Functional Analysis · Mathematics 2020-06-08 Jieun Ahn , Sunyoung Jang

We associate a $C^*$-algebra to a partial action of the integers acting on the base space of a vector bundle, using the framework of Cuntz--Pimsner algebras. We investigate the structure of the fixed point algebra under the canonical gauge…

Operator Algebras · Mathematics 2025-06-23 Aaron Kettner

We provide a Cuntz-Pimsner model for graph of groups $C^*$-algebras. This allows us to compute the $K$-theory of a range of examples and show that graph of groups $C^*$-algebras can be realised as Exel-Pardo algebras. We also make a…

Operator Algebras · Mathematics 2021-07-27 Alexander Mundey , Adam Rennie

We extend the theory of perturbations of KMS states to some class of unbounded perturbations using noncommutative Lp-spaces. We also prove certain stability of the domain of the Modular Operator associated to a ||.||p-continuous state. This…

Mathematical Physics · Physics 2018-08-13 R. Correa da Silva