Fock Space of Level infinity and Characters of Vertex Operators
arXiv:2008.07287
Abstract
We present an extension of the trace of a vertex operator and explain a representation-theoretic interpretation of the trace. Specifically, we consider a twist of the vertex operator with infinitely many Casimir operators and compute its trace as a character formula. To do this, we define the Fock space of infinite level . Then, we prove a duality between and of Howe type, which provides a decomposition of into irreducible representations with joint highest weight vector for and . The decomposition of the Fock space into highest weight representations provides a method to calculate and interpret the extended trace.