One-point functions for $C_2$-cofinite VOAs: pseudo-traces and trace spaces of projective modules

Abstract

We study the space of one-point functions on the torus for a possibly nonrational $C_2$-cofinite vertex operator algebra $V$ by relating it to a trace object of the subcategory of projective objects in the representation category of $V$. We identify the dual of the trace space with symmetric functions on the endomorphism algebra $E$ of a projective generator. Motivated by the Gainutdinov-Runkel conjecture, recently established using different methods by Gui and Zhang, we present a complementary representation-theoretic approach based on Arike-Nagatomo pseudo-traces. In this framework, we prove surjectivity of the Gainutdinov-Runkel map from symmetric functions on $E$ to one-point functions. Under the additional assumption of separated conformal weights modulo $\mathbb{Z}$, we also prove injectivity, using projective-cover techniques inspired by Huang.