For a finite-index [Formula: see text] subfactor [Formula: see text], we prove the existence of a universal Hopf â-algebra (or, a discrete quantum group in the analytic language) acting on [Formula: see text] in a trace-preserving fashion and fixing [Formula: see text] pointwise. We call this Hopf â-algebra the quantum Galois group for the subfactor and compute it in some examples of interest, notably for arbitrary irreducible finite-index depth-two subfactors. Along the way, we prove the existence of universal acting Hopf algebras for more general structures (tensors in enriched categories), in the spirit of recent work by Agore, Gordienko and Vercruysse.
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Galois Correspondence and Fourier Analysis on Local Discrete Subfactors
Discrete subfactors include a particular class of infinite index subfactors and all finite index ones. A discrete subfactor is called local when it is braided and it fulfills a commutativity condition motivated by the study of inclusion of Quantum Field Theories in the algebraic HaagâKastler setting. In Bischoff et al. (J Funct Anal 281(1):109004, 2021), we proved that every irreducible local discrete subfactor arises as the fixed point subfactor under the action of a canonical compact hypergroup. In this work, we prove a Galois correspondence between intermediate von Neumann algebras and closed subhypergroups, and we study the subfactor theoretical Fourier transform in this context. Along the way, we extend the main results concerning đŒ-induction and đ-restriction for braided subfactors previously known in the finite index case.
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- Award ID(s):
- 1821162
- PAR ID:
- 10325943
- Date Published:
- Journal Name:
- Annales Henri Poincaré
- ISSN:
- 1424-0637
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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