KMS states on $\mathbb{Z}_2$-crossed products and twisted KMS functionals

Fuente: arXiv
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Autori principali: da Silva, Ricardo Correa, Grosse, Johannes, Lechner, Gandalf
Natura: Preprint
Pubblicazione: 2024
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author da Silva, Ricardo Correa
Grosse, Johannes
Lechner, Gandalf
author_facet da Silva, Ricardo Correa
Grosse, Johannes
Lechner, Gandalf
contents KMS states on $\mathbb{Z}_2$-crossed products of unital $C^*$-algebras $\mathcal{A}$ are characterized in terms of KMS states and twisted KMS functionals of $\mathcal{A}$. These functionals are shown to describe the extensions of KMS states $ω$ on $\mathcal{A}$ to the crossed product $\mathcal{A} \rtimes \mathbb{Z}_2$ and can also be characterized by the twisted center of the von Neumann algebra generated by the GNS representation corresponding to $ω$. As a particular class of examples, KMS states on $\mathbb{Z}_2$-crossed products of CAR algebras with dynamics and grading given by Bogoliubov automorphisms are analyzed in detail. In this case, one or two extremal KMS states are found depending on a Gibbs type condition involving the odd part of the absolute value of the Hamiltonian. As an application in mathematical physics, the extended field algebra of the Ising QFT is shown to be a $\mathbb{Z}_2$-crossed product of a CAR algebra which has a unique KMS state.
format Preprint
id arxiv_https___arxiv_org_abs_2402_15574
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle KMS states on $\mathbb{Z}_2$-crossed products and twisted KMS functionals
da Silva, Ricardo Correa
Grosse, Johannes
Lechner, Gandalf
Operator Algebras
Mathematical Physics
KMS states on $\mathbb{Z}_2$-crossed products of unital $C^*$-algebras $\mathcal{A}$ are characterized in terms of KMS states and twisted KMS functionals of $\mathcal{A}$. These functionals are shown to describe the extensions of KMS states $ω$ on $\mathcal{A}$ to the crossed product $\mathcal{A} \rtimes \mathbb{Z}_2$ and can also be characterized by the twisted center of the von Neumann algebra generated by the GNS representation corresponding to $ω$. As a particular class of examples, KMS states on $\mathbb{Z}_2$-crossed products of CAR algebras with dynamics and grading given by Bogoliubov automorphisms are analyzed in detail. In this case, one or two extremal KMS states are found depending on a Gibbs type condition involving the odd part of the absolute value of the Hamiltonian. As an application in mathematical physics, the extended field algebra of the Ising QFT is shown to be a $\mathbb{Z}_2$-crossed product of a CAR algebra which has a unique KMS state.
title KMS states on $\mathbb{Z}_2$-crossed products and twisted KMS functionals
topic Operator Algebras
Mathematical Physics
url https://arxiv.org/abs/2402.15574