A Conjecture of Warnaar-Zudilin from Deformations of Lie Superalgebras

We prove a collection of $q$-series identities conjectured by Warnaar and Zudilin and appearing in recent work with H. Kim in the context of superconformal field theory. Our proof utilizes a deformation of the simple affine vertex operator superalgebra $L_k({\mathfrak{o}\mathfrak{s}\mathfrak{p}}_{1\mathrm{\mid }2n})$ into the principal subsuperspace of $L_k({\mathfrak{s}\mathfrak{l}}_{1\mathrm{\mid }2n+1})$ in a manner analogous to earlier work of Feigin-Stoyanovsky. This result fills a gap left by Stoyanovsky, showing that for all positive integers $N$, $k$ the character of the principal subspace of type $A_N$ at level $k$ can be identified with the (super)character of a simple affine vertex operator (super)algebra at the same level.