RCFT correlators as equivalences of modular functors

Abstract: The local information of a 2d rational conformal field theory (RCFT) is encoded in a vertex operator algebra, whose modules constitute a modular fusion category C. The collection of global observables of the theory is given by conformal blocks and carries actions of mapping class groups, which is described mathematically by a modular functor that assigns the Drinfeld center Z(C) to a circle. The string-net construction, which first appeared in the study of topological phases of matter, not only provides such a modular functor but also supplies a graphical construction of correlators. A generalization of the string-net construction takes a pivotal bicategory as input. When such a bicategory is taken to be C (considered as a bicategory with one object), it recovers the modular functor of conformal blocks. On the other hand, the modular functor associated with the Morita bicategory of separable symmetric Frobenius algebras internal to C classifies stratified worldsheets up to "categorical symmetries". In this talk we explain, using the framework of double categories, that RCFT correlators exhibit an equivalence between these two modular functors. This is in fact a consequence of the functoriality of the string-net construction: the lax biadjunction between a pivotal bicategory and its orbifold completion induces an equivalence between their string-net modular functors.

mathematical physicsalgebraic topologycategory theoryquantum algebra

Audience: researchers in the topic

Topological Quantum Field Theory Club (IST, Lisbon)

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