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SIGMA, 2024 Volume 20, 085, 21 pp. (Mi sigma2087)

The Racah Algebra of Rank 2: Properties, Symmetries and Representation

Sarah Post, Sébastien Bertrand

Department of Mathematics, University of Hawai'i at Mānoa, Honolulu, Hawai'i, USA

Abstract: The goals of this paper are threefold. First, we provide a new “universal” definition for the Racah algebra of rank 2 as an extension of the rank-1 Racah algebra where the generators are indexed by subsets and any three disjoint indexing sets define a subalgebra isomorphic to the rank-1 case. With this definition, we explore some of the properties of the algebra including verifying that these natural assumptions are equivalent to other defining relations in the literature. Second, we look at the symmetries of the generators of the rank-2 Racah algebra. Those symmetries allows us to partially make abstraction of the choice of the generators and write relations and properties in a different format. Last, we provide a novel representation of the Racah algebra. This new representation requires only one generator to be diagonal and is based on an expansion of the split basis representation from the rank-1 Racah algebra.

Keywords: Racah algebra, representation, symmetry, rank-2.

MSC: 81R12, 20C35

Received: March 8, 2024; in final form September 10, 2024; Published online September 22, 2024

Language: English

DOI: 10.3842/SIGMA.2024.085


ArXiv: 2402.08944


© Steklov Math. Inst. of RAS, 2026