$K$-theory associated to vertex operator algebras
  We introduce two $K$-theories, one for vector bundles whose fibers are modules of vertex operator algebras, another for vector bundles whose fibers are modules of associative algebras. We verify the cohomological properties of these $K$-theories, and construct a natural homomorphism from the VOA K-theory to the associative algebra K-theory. 
Chongying Dong, Kefeng Liu, Xiaonan Ma, Jian Zhou