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The classification of superconformal field theories predicts the existence of such a theory with $(2,0)$-supersymmetry in dimension 6, which is such that it contains a self-dual higher gauge theory whose field configurations are connections on a 2-bundle (a circle 2-bundle with connection in the abelian case).
It is expected (Witten 07) that such theories arise as the worldvolume theories of M5-branes and that their compactifications are at the heart of the phenomenon that leads to S-duality and hence geometric Langlands duality (Witten 09).
Due to the self-duality a characterization of these theories by an action functional is at best subtle, maybe impossible. Therefore more direct descriptions are still under investigation (for instance SSW11). A review of recent developments is in (Moore11).
Under AdS7/CFT6 the 6d $(2,0)$-superconformal QFT is supposed to be dual to M-theory on anti de Sitter spacetime $AdS_7 \times S^4$.
See AdS/CFT correspondence for more on this.
The 5d $(2,0)$-SCFT has tensionless 1-brane configurations. From the point of view of the ambient 11-dimensional supergravity these are the boundaries of M2-branes ending on the M5-branes. (GGT)
(graphics taken from (Workshop 14))
The compactification of the 5-brane on a Riemann surface yields as worldvolume theory N=2 D=4 super Yang-Mills theory. See at N=2 D=4 SYM – Construction by compactification of 5-branes.
The AGT correspondence relates the partition function of $SU(2)^{n+3g-3}$-N=2 D=4 super Yang-Mills theory obtained by compactifying the $6d$ M5-brane theory on a Riemann surface $C_{g,n}$ of genus $g$ with $n$ punctures to 2d Liouville theory on $C_{g,n}$.
More generally, this kind of construction allows to describe the 6d (2,0)-theory as a “2d SCFT with values in 4d SYM”. See at AGT correspondence for more on this.
Famously the solutions to self-dual Yang-Mills theory in dimension 4 can be obtained as images of degree-2 cohomology classes under the Penrose-Ward twistor transform. Since the 6d QFT on the M5-brane contains a 2-form self-dual higher gauge field it seems natural to expect that it can be described by a higher analogy of the twistor transform. For references exploring this idea see at twistor space – References – Application to the self-dual 2-form field in 6d.
gauge theory induced via AdS-CFT correspondence
M-theory perspective via AdS7-CFT6 | F-theory perspective |
---|---|
11d supergravity/M-theory | |
$\;\;\;\;\downarrow$ Kaluza-Klein compactification on $S^4$ | compactificationon elliptic fibration followed by T-duality |
7-dimensional supergravity | |
$\;\;\;\;\downarrow$ topological sector | |
7-dimensional Chern-Simons theory | |
$\;\;\;\;\downarrow$ AdS7-CFT6 holographic duality | |
6d (2,0)-superconformal QFT on the M5-brane with conformal invariance | M5-brane worldvolume theory |
$\;\;\;\; \downarrow$ KK-compactification on Riemann surface | double dimensional reduction on M-theory/F-theory elliptic fibration |
N=2 D=4 super Yang-Mills theory with Montonen-Olive S-duality invariance; AGT correspondence | D3-brane worldvolume theory with type IIB S-duality |
$\;\;\;\;\; \downarrow$ topological twist | |
topologically twisted N=2 D=4 super Yang-Mills theory | |
$\;\;\;\; \downarrow$ KK-compactification on Riemann surface | |
A-model on $Bun_G$, Donaldson theory |
$\,$
gauge theory induced via AdS5-CFT4 |
---|
type II string theory |
$\;\;\;\;\downarrow$ Kaluza-Klein compactification on $S^5$ |
$\;\;\;\; \downarrow$ topological sector |
5-dimensional Chern-Simons theory |
$\;\;\;\;\downarrow$ AdS5-CFT4 holographic duality |
N=4 D=4 super Yang-Mills theory |
$\;\;\;\;\; \downarrow$ topological twist |
topologically twisted N=4 D=4 super Yang-Mills theory |
$\;\;\;\; \downarrow$ KK-compactification on Riemann surface |
A-model on $Bun_G$ and B-model on $Loc_G$, geometric Langlands correspondence |
Table of branes appearing in supergravity/string theory (for classification see at brane scan).
The first indication of a 6d theory with a self-dual 2-form field appears in section 1 of
Surveys include
Greg Moore, On the role of six‐dimensional $(2,0)$-theories in recent developments in Physical Mathematics , talk at Strings2011 (pdf slides)
Greg Moore, Applications of the six-dimensional (2,0) theories to Physical Mathematics, Felix Klein lectures Bonn (2012) (pdf)
Workshops include
at the University of California, Berkeley
See also the references and discussion at M5-brane.
The conformal structure of the 6d theory and its relation under compactification on a Riemann surface to electric-magnetic duality/S-duality in 4-dimensions is discussed in
and the resulting relation to the geometric Langlands correspondence is disucssed in
For more references on this see at N=2 D=4 super Yang-Mills theory the section References - Constructions from 5-branes.
Relation to BFSS matrix model on tori:
Discussion of the ADE classification of the 6d theories includes, after (Witten95)
Julie D. Blum, Kenneth Intriligator, New Phases of String Theory and 6d RG Fixed Points via Branes at Orbifold Singularities, Nucl.Phys.B506:199-222,1997 (arXiv:hep-th/9705044)
Jonathan Heckman, David Morrison, Cumrun Vafa, On the Classification of 6D SCFTs and Generalized ADE Orbifolds (arXiv:1312.5746)
Realization of the 6d theory in F-theory is discussed in (Heckmann-Morrison-Vafa 13).
A proposal for related higher nonabelian differential form data is made in
Since by transgression every nonabelian principal 2-bundle/gerbe gives rise to some kind of nonabelian 1-bundle on loop space it is clear that some parts (but not all) of the nonabelian gerbe theory on the 5-brane has an equivalent reformulation in terms of ordinary gauge theory on the loop space of the 5-brane and possibly for gauge group the loop group of the original gauge group.
Comments along these lines have been made in
In fact, via the strict 2-group version of the string 2-group there is a local gauge in which the loop group variables appear already before transgression of the 5-brane gerbe to loop space. This is discussed from a holographic point of view in
The basics of the relation of the 6d theory to a 7d theory under AdS-CFT is reviewed holographic duality
The argument that the abelian 7d Chern-Simons theory of a 3-connection yields this way the conformal blocks of the abelian self-dual higher gauge theory of the 6d theory on a single brane is due to
Edward Witten, Five-Brane Effective Action In M-Theory J. Geom. Phys.22:103-133,1997 (arXiv:hep-th/9610234)
Edward Witten, AdS/CFT Correspondence And Topological Field Theory JHEP 9812:012,1998 (arXiv:hep-th/9812012)
The nonabelian generalization of this 7d action functional that follows from taking the quantum corrections (Green-Schwarz mechanism and flux quantization) of the supergravity C-field into account is discussed in
See also
Eric D'Hoker, John Estes, Michael Gutperle, Darya Krym,
Exact Half-BPS Flux Solutions in M-theory I Local Solutions (arXiv:0806.0605)
Exact Half-BPS Flux Solutions in M-theory II: Global solutions asymptotic to $AdS_7 \times S^4$ (arXiv:0810.4647)
Jerome Gauntlett, Joaquim Gomis, Paul Townsend, BPS Bounds for Worldvolume Branes (arXiv:hep-th/9711205)
P.S. Howe, Neil Lambert, Peter West, The Threebrane Soliton of the M-Fivebrane (arXiv:hep-th/9710033)
Relation to extended TQFT is discussed in
David Ben-Zvi, Algebraic geometry of topological field theories, talk at Reimagining the Foundations of Algebraic Topology April 07, 2014 - April 11, 2014 (web video)