# Contents

## Idea

The D-brane of dimension 6+1 in type IIA string theory.

## Relation to other branes

### To the KK-monopole in M-theory

The lift of the D6 to M-theory is the Kaluza-Klein monopole there (Townsend 95).

One way to understand this is as follows: the first Chern class of the M-theory circle bundle is the D0-brane degree-2 RR-field strength $R_0$. By the self-duality of the RR-fields this is the Hodge dual of the D6-brane degree-8 field strength. Now given a Kaluza-Klein monopole after removing the locus of the monopole where the circle-fiber degenerates (as in the original Dirac charge quantization argument) it is a non-degenerated circle bundle such that the integral of the 2-form $R_0$ over any 2-sphere surrounding the singular locus is non-trivial. By the usual yoga of electric-magnetic duality this integral measures the magnetic flux of a D6-brane sitting at the singular locus. For more on this see at Kaluza-Klein monopole – Relation to the D6-brane, and see at M-theory lift of gauge enhancement on D6-branes.

### To D7-branes

The T-dual of the D6 branes is the D7-brane in type IIB string theory.

### Table of branes

from M-branes to F-branes: superstrings, D-branes and NS5-branes

M-theory on $S^1_A \times S^1_B$-elliptic fibrationKK-compactification on $S^1_A$type IIA string theoryT-dual KK-compactification on $S^1_B$type IIB string theoryF-theory on elliptically fibered-K3 fibrationduality between F-theory and heterotic string theoryheterotic string theory on elliptic fibration
M2-brane wrapping $S_A^1$double dimensional reduction $\mapsto$type IIA superstring$\mapsto$type IIB superstring$\mapsto$heterotic superstring
M2-brane wrapping $S_B^1$$\mapsto$D2-brane$\mapsto$D1-brane
M2-brane wrapping $p$ times around $S_A^1$ and $q$ times around $S_B^1$$\mapsto$$p$ strings and $q$ D2-branes$\mapsto$(p,q)-string
M5-brane wrapping $S_A^1$double dimensional reduction $\mapsto$D4-brane$\mapsto$D5-brane
M5-brane wrapping $S_B^1$$\mapsto$NS5-brane$\mapsto$NS5-brane$\mapsto$NS5-brane
M5-brane wrapping $p$ times around $S_A^1$ and $q$ times around $S_B^1$$\mapsto$$p$ D4-brane and $q$ NS5-branes$\mapsto$(p,q)5-brane
M5-brane wrapping $S_A^1 \times S_B^1$$\mapsto$$\mapsto$D3-brane
KK-monopole/A-type ADE singularity (degeneration locus of $S^1_A$-circle fibration, Sen limit of $S^1_A \times S^1_B$ elliptic fibration)$\mapsto$D6-brane$\mapsto$D7-branesA-type nodal curve cycle degenertion locus of elliptic fibration (Sen 97, section 2)SU-gauge enhancement
KK-monopole orientifold/D-type ADE singularity$\mapsto$D6-brane with O6-planes$\mapsto$D7-branes with O7-planesD-type nodal curve cycle degenertion locus of elliptic fibration (Sen 97, section 3)SO-gauge enhancement
exceptional ADE-singularity$\mapsto$$\mapsto$exceptional ADE-singularity of elliptic fibration$\mapsto$E6-, E7-, E8-gauge enhancement

(e.g. Johnson 97, Blumenhagen 10)

## Phenomenology – Intersecting D-brane models

D6-branes are the main ingredient in type IIA string phenomenology in the guise of intersecting D-brane models, see also at string phenomenology the section Models in type II with intersecting branes.

graphics grabbed from Ibáñez-Uranga 12

Table of branes appearing in supergravity/string theory (for classification see at brane scan).

branein supergravitycharged under gauge fieldhas worldvolume theory
black branesupergravityhigher gauge fieldSCFT
D-branetype IIRR-fieldsuper Yang-Mills theory
$(D = 2n)$type IIA$\,$$\,$
D0-brane$\,$$\,$BFSS matrix model
D2-brane$\,$$\,$$\,$
D4-brane$\,$$\,$D=5 super Yang-Mills theory with Khovanov homology observables
D6-brane$\,$$\,$D=7 super Yang-Mills theory
D8-brane$\,$$\,$
$(D = 2n+1)$type IIB$\,$$\,$
D(-1)-brane$\,$$\,$$\,$
D1-brane$\,$$\,$2d CFT with BH entropy
D3-brane$\,$$\,$N=4 D=4 super Yang-Mills theory
D5-brane$\,$$\,$$\,$
D7-brane$\,$$\,$$\,$
D9-brane$\,$$\,$$\,$
(p,q)-string$\,$$\,$$\,$
(D25-brane)(bosonic string theory)
NS-branetype I, II, heteroticcircle n-connection$\,$
string$\,$B2-field2d SCFT
NS5-brane$\,$B6-fieldlittle string theory
D-brane for topological string$\,$
A-brane$\,$
B-brane$\,$
M-brane11D SuGra/M-theorycircle n-connection$\,$
M2-brane$\,$C3-fieldABJM theory, BLG model
M5-brane$\,$C6-field6d (2,0)-superconformal QFT
M9-brane/O9-planeheterotic string theory
M-wave
topological M2-branetopological M-theoryC3-field on G2-manifold
topological M5-brane$\,$C6-field on G2-manifold
solitons on M5-brane6d (2,0)-superconformal QFT
self-dual stringself-dual B-field
3-brane in 6d

## References

The relation to the Kaluza-Klein monopole in M-theory is due to

Further discussion and derivation of the Chan-Paton gauge field content on the D6 from the KK-monopole is discussed in

Discussion of D6 intersecting branes for intersecting D-brane models:

• Angel Uranga, Model building in IIA: Intersecting

brane worlds_, 2012 (pdf)

Last revised on May 28, 2018 at 07:54:58. See the history of this page for a list of all contributions to it.