Abstract We give criteria for determining the positivity of line bundles coming from vertex operator algebras (VOAs) on the moduli space M₀, ₍ of rational curves with n marked points. The criteria use the multiplicative structure of VOA representations encoded in the fusion ring. Using them, we construct positive line bundles on M₀, ₍ from certain parafermion VOAs. These give the first examples of commutant VOAs producing positive line bundles.
Avik Chakravarty (Tue,) studied this question.