Fusion rules and complete reducibility of certain modules for affine Lie algebras
D Adamovic, O Perse — arXiv preprint arXiv:1207.7177, 2012 — arxiv.org
... Vertex operator algebra Mℓ is simple and admits the charge decomposition Mℓ =
⊕s∈ZM (s) ℓ . The charge zero subspace M (0) ℓ is a simple vertex operator subalgebra
of Mℓ which contains the vertex operator algebra ˜LA (1) ℓ−1 (−Λ0) ...