Kaluza Klein in 8 dimensions with the 4 dimensional compact space being the homogeneous space H=SU(3)/SU(2)xU(1), so that the resulting KK bosons are those of SU(3). Similarly, KK in 10 dimensions with H x T^2 as compactified space will produce a SU(3)xU(1)^2 gauge theory.(adsbygoogle = window.adsbygoogle || []).push({});

For energies smaller that the compactificacion scale, this theory is QCD. So it has (empirically, at least) confinement, and it has an implicit string theory, the one of the QCD flux tube. One could even tell of two open string theories: an oriented one, where pairs of particle and antiparticle lie in the extremes of the string, and an unoriented one, where the extremes can be of the same SU(3) irrep, say two quarks or two antiquarks. Are the extremes of these strings confined to live in the 3-brane of space-time?

I pondered how relevant QCD was to strings after a post http://www.nonequilibrium.net/108-how-stringy-is-qcd-string/

I wonder why the forces coming from KK are not considered in most models of superstring theory. Or are they considered but in a hidden way?

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# Quirks and exta dimensions.

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