For targets
For targets
For discrete targets
For targets
For targets extending the
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Chern-Simons-
for higher abelian targets
for targets
for the $L_\infty$-structure on the of the closed :
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topological AdS7/CFT6-sector
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Axiomatizations
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Tools
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Structural phenomena
Types of quantum field thories
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examples
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The Yetter model is a 4d TQFT sigma-model quantum field theory whose target space is a discrete 2-groupoid and whose background gauge field is a circle 4-bundle.
Together with the Dijkgraaf-Witten model these form the first two steps in filtering of target spaces by homotopy type truncation of ∞-Chern-Simons theory with discrete target spaces. It is hence also an example of a 4d Chern-Simons theory.
The Yetter model is not the same as the Crane-Yetter model.
Fix
$G$ a discrete 2-group; write $\mathbf{B}G$ for its delooping 2-groupoid;
$\alpha : \mathbf{B}G \to \mathbf{B}^4 U(1)$ a characteristic class with coefficients in the circle 4-group. This is equivalently a cocycle in degree $4$ group cohomology
The Yetter-model is the ∞-Dijkgraaf-Witten theory induced by this data.
The model without a background gauge field/cocycle was considered in
The effect of having a nontrivial group 4-cocycle was considered (but now only on a 1-group) in
D. Birmingham, M. Rakowski, On Dijkgraaf-Witten Type Invariants, Lett. Math. Phys. 37 (1996), 363.
Marco Mackaay, Spherical 2-categories and 4-manifold invariants, Adv. Math. 153 (2000), no. 2, 353–390. (arXiv:math/9805030)
.
The reinterpretation of the “state sum” equation used in the above publications as giving homomorphisms of simplicial sets/topological spaces is given in
and then extended to colorings in homotopy n-types in
See also
(TAC)
which has some remarks about higher (2-)group cocycles towards the end.
Last revised on November 18, 2014 at 22:13:22. See the history of this page for a list of all contributions to it.