I would like to know of good pedagogic references to learn about the notion of "defects" in TFTs and CFTs. I am specially interested in 3+1 TFTs (.and probably about their relation to 2+1 CFTs..)
In the same strain I would like to know of references which explain whatever is known about being able to translate defects and any other such non-local structures for TFTs into CFTs in one lower dimension. I guess such a dictionary exists and I would like to know of references about it, especially for 3+1 TFTs and their "related" 2+1 CFTs.
(..I guess there is some intuition about defects in TFTs being writable as boundary condition changing operators in CFTs in lower dimension..it would be great if someone can provide some references in that direction..)