We define a Turaev-Viro-Barrett-Westbury state sum model of triangulated
3-manifolds with surface defects (oriented 2d surfaces), line defects
and point defects (graphs on the defect surfaces). Surface defects are
labeled with bimodule categories over spherical fusion categories with
bimodule traces, line and point defects with bimodule functors and
bimodule natural transformations.
The state sum uses generalised 6j-symbols that encode the coherence
isomorphisms of the defect data. We prove the triangulation independence
of the state sum and show that it can be computed with polygon diagrams
that satisfy the cutting and gluing identities for polygon
presentations of oriented surfaces. State sums detect the genus of a
defect surface and are sensitive to its embedding. Defect lines on
defect surfaces with trivial defect data define ribbon invariants for
the centre of the underlying spherical fusion category.
Reference: C. Meusburger, State sum models with defects based on
spherical fusion categories, Adv. Math. 429 (2023), DOI:
10.1016/j.aim.2023.109177