Orbifold construction of holomorphic vertex operator algebras associated to inner automorphisms

Abstract: In this article, we construct three new holomorphic vertex operator algebras of central charge $24$ using the $\mathbb{Z}2$-orbifold construction associated to inner automorphisms. Their weight one subspaces has the Lie algebra structures $D{7,3}A_{3,1}G_{2,1}$, $E_{7,3}A_{5,1}$, and $A_{8,3}A_{2,1}^2$. In addition, we discuss the constructions of holomorphic vertex operator algebras with Lie algebras $A_{5,6}C_{2,3}A_{1,2}$ and $D_{6,5}A_{1,1}^2$ from holomorphic vertex operator algebras with Lie algebras $C_{5,3}G_{2,2}A_{1,1}$ and $A_{4,5}^2$, respectively.