%0 Journal Article %T Characterizing Invariants for Local Extensions of Current Algebras %A K. -H. Rehren %A Ya. S. Stanev %A I. T. Todorov %J Physics %D 1994 %I arXiv %R 10.1007/BF02101529 %X Pairs $\aa \subset \bb$ of local quantum field theories are studied, where $\aa$ is a chiral conformal \qft and $\bb$ is a local extension, either chiral or two-dimensional. The local correlation functions of fields from $\bb$ have an expansion with respect to $\aa$ into \cfb s, which are non-local in general. Two methods of computing characteristic invariant ratios of structure constants in these expansions are compared: $(a)$ by constructing the monodromy \rep of the braid group in the space of solutions of the Knizhnik-Zamolodchikov differential equation, and $(b)$ by an analysis of the local subfactors associated with the extension with methods from operator algebra (Jones theory) and algebraic quantum field theory. Both approaches apply also to the reverse problem: the characterization and (in principle) classification of local extensions of a given theory. %U http://arxiv.org/abs/hep-th/9409165v1