Quantum Dimensions and Quantum Galois Theory
  The quantum dimensions of modules for vertex operator algebras are defined and their properties are discussed. The possible values of the quantum dimensions are obtained for rational vertex operator algebras. A criterion for simple currents of a rational vertex operator algebra is given. A full Galois theory for rational vertex operator algebras is established using the quantum dimensions. 
Chongying Dong, Xiangyu Jiao and Feng Xu
math.QA math.OA