On some components of $L(ρ)\otimes L(ρ)$ associated with rooted trees for symmetrizable Kac-Moody algebras

Abstract

Let $\mathfrak{g}$ be a symmetrizable Kac-Moody algebra over $\mathbb{C}$ and let $L(ρ)$ be the irreducible integrable $\mathfrak{g}$-module with highest weight $ρ$. Let $I$ be a subgraph of the Dynkin diagram of $\mathfrak{g}$ which has only simple bonds and no cycle of length $\geq 3$. For every subset $D$ of $I$, denote by $β_D$ the sum of the simple roots corresponding to $D$. To every $D \subset I$ such that $λ_{D,I} = 2ρ- β_I - β_D$ is dominant, we associate certain elements $π_{D,I}$ of weight $λ_{D,I} {-} ρ$ in the crystal $B(ρ)$, which depend on the choice of a root vertex in each connected component of $I$. Then we prove that our elements are $ρ$-dominant elements of $B(ρ)$, hence provide new families of components of the tensor product $L(ρ)\otimes L(ρ)$.