Linear idempotents in Matsuo algebras

Abstract

Matsuo algebras are an algebraic incarnation of 3-transposition groups with a parameter $\alpha$, where idempotents takes the role of the transpositions. We show that a large class of idempotents in Matsuo algebras satisfy the Seress property, making these nonassociative algebras well-behaved analogously to associative algebras, Jordan algebras and vertex (operator) algebras. We calculate eigenvalues in the Matsuo algebra of $\mathrm{Sym}(n)$ for any $\alpha$, generalising some vertex algebra results for which $\alpha =\frac{1}{4}$. Finally, in the Matsuo algebra of the root system ${\mathrm{D}}_n$, we show $n-3$ conjugacy classes of involutions coming from the Weyl group are in natural bijection with idempotents in the algebra via their fusion rules.

16 pages, comments welcome, to appear Indiana Uni Math J