Orbifold Vertex Operator Algebras and the Positivity Condition
arXiv:1803.03702
Abstract
In this note we show that the irreducible twisted modules of a holomorphic, -cofinite vertex operator algebra have -weights at least as large as the smallest -weight of . Hence, if is of CFT-type, then the twisted -modules are almost strictly positively graded. This in turn implies that the fixed-point vertex operator subalgebra for a finite, solvable group of automorphisms of almost satisfies the positivity condition. These and some further results are obtained by a careful analysis of Dong, Li and Mason's twisted modular invariance.
10 pages, LaTeX; comments welcome