Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Search options answers only not deleted user 78

Topological quantum field theory.

11 votes
Accepted

Trace of a functor (or dimension of a category) in extended 2d TQFTs

I won't be able to give any references, so I hope some more experts can help me out, as there is much work on traces of functors. In general, there are two reasonable notions of "trace" of a functor, …
Theo Johnson-Freyd's user avatar
6 votes

Reshetikhin-Turaev as a 3-2-1-theory

The traditional way to define Reshetikhin–Turaev's version of Chern–Simons TQFT as a 321 theory assigns to the circle the category of representations of the quantum group at fixed root of unity (depen …
Theo Johnson-Freyd's user avatar
10 votes
Accepted

Is Segal's notion of conformal field theory a quantum field theory in the sense of Wightman ...

My understanding is that Segal invented his formalism (which was then adapted by Atiyah) by thinking about the same thing Wightman was thinking about: formalising the theory of local operators. In hin …
Theo Johnson-Freyd's user avatar
9 votes
Accepted

Stably-framed cobordism $(\infty,n)$-category

Yes, there is a stably-framed bordism category. Recall that tangential structures on smooth $n$-manifolds can be parameterized by maps $X \to BO(n)$; an $X$-structure on $M$ is then by definition a li …
Theo Johnson-Freyd's user avatar
8 votes

What is Chern-Simons theory?

Some good references are the papers by Dan Freed and the book The geometry and physics of knots by Michael Atiyah. But by far the best answer to your question is in Witten's paper "Quantum field theo …
Theo Johnson-Freyd's user avatar
3 votes

Generalization of Drinfeld double to comodule algebras

I think Davydov's papers Centre of an algebra and Full centre of an H-module algebra might be what you are looking for.
Theo Johnson-Freyd's user avatar
8 votes

Resources for graphical languages / Penrose notation / Feynman diagrams / birdtracks?

I'll echo supercooldave's vote for TikZ. For applications to knot theory, Kassel's longer book is great, as is his short book with Rosso and Turaev on quantum groups and knots. Kauffman's book Knot …
3 votes
Accepted

2-morphisms for Bord(n)

The endomorphisms of the interval are, at this informal level of discussion, surfaces with $S^1$ boundary. More generally, if you want to talk about $\hom(M,N)$, where $M$ and $N$ are $k$-dimensional …
Theo Johnson-Freyd's user avatar
21 votes

Fully extended TQFT and lattice models

It may take a bit of extraction, but positive answers to both of your questions follow from my results joint with Gaiotto in Condensations in higher categories (arXiv:1905.09566). In that paper we bui …
Theo Johnson-Freyd's user avatar
13 votes

Grothendieck group of the category of boundary conditions of topological field theory

To understand the possible spaces of boundary conditions for a TQFT, it is helpful to start in highest dimension. Suppose you have a $(d+1)$-dimensional nonanomalous TQFT $\mathcal Q$. (The anomalous …
Theo Johnson-Freyd's user avatar