Admissible level $\mathfrak{osp}(1|2)$ minimal models and their relaxed highest weight modules

Abstract: The minimal model $\mathfrak{osp}(1|2)$ vertex operator superalgebras are the simple quotients of affine vertex operator superalgebras constructed from the affine Lie super algebra $\widehat{\mathfrak{osp}}(1|2)$ at certain rational values of the level $k$. We classify all isomorphism classes of $\mathbb{Z}_2$-graded simple relaxed highest weight modules over the minimal model $\mathfrak{osp}(1|2)$ vertex operator superalgebras in both the Neveu-Schwarz and Ramond sectors. To this end, we combine free field realisations, screening operators and the theory of symmetric functions in the Jack basis to compute explicit presentations for the Zhu algebras in both the Neveu-Schwarz and Ramond sectors. Two different free field realisations are used depending on the level. For $k<-1$, the free field realisation resembles the Wakimoto free field realisation of affine $\mathfrak{sl}(2)$ and is originally due to Bershadsky and Ooguri. It involves 1 free boson (or rank 1 Heisenberg vertex algebra), one $\beta\gamma$ bosonic ghost system and one $bc$ fermionic ghost system. For $k>-1$, the argument presented here requires the bosonisation of the $\beta\gamma$ system by embedding it into an indefinite rank 2 lattice vertex algebra.