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On multiparameter CAR (canonical anticommutation relation) flows

Published online by Cambridge University Press:  09 January 2025

C. H. Namitha
Affiliation:
The Institute of Mathematical Sciences, A CI of Homi Bhabha National Institute, 4th Cross Street, CIT Campus, Taramani, Chennai, India, 600113 e-mail: [email protected]
S. Sundar*
Affiliation:
The Institute of Mathematical Sciences, A CI of Homi Bhabha National Institute, 4th Cross Street, CIT Campus, Taramani, Chennai, India, 600113 e-mail: [email protected]

Abstract

Let P be a pointed, closed convex cone in $\mathbb {R}^d$. We prove that for two pure isometric representations $V^{(1)}$ and $V^{(2)}$ of P, the associated CAR flows $\beta ^{V^{(1)}}$ and $\beta ^{V^{(2)}}$ are cocycle conjugate if and only if $V^{(1)}$ and $V^{(2)}$ are unitarily equivalent. We also give a complete description of pure isometric representations of P with commuting range projections that give rise to type I CAR flows. We show that such an isometric representation is completely reducible with each irreducible component being a pullback of the shift semigroup $\{S_t\}_{t \geq 0}$ on $L^2[0,\infty )$. We also compute the index and the gauge group of the associated CAR flows and show that the action of the gauge group on the set of normalized units need not be transitive.

Type
Article
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of Canadian Mathematical Society

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