O(N_c) and U Sp(N_c) QCD from String Theory(Particles and Fields)

概要

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We propose a holographic dual of large N_c quantum chromodynamics (QCD) with the gauge groups O(N_c) and U Sp(N_c) and N_f flavors of massless quarks. This is constructed by adding O6-planes to an intersecting D4-D8 system in type IIA superstring theory. The holographic dual description is formulated in Witten's D4-brane background with D8-branes and O6-planes embedded in it as probes. The D4-brane background gives rise to a smooth interpolation of D8-<D8>^^^- pairs and an O6-<O6>^^^- pair. We show that the resultant brane configuration explains geometrically the flavor symmetry breaking patterns in O(N_c) and USp(N_c) QCD, which are caused by quark bilinear condensates. We next discuss that baryons can be realized as D4-<D4>^^^- pairs wrapped on S^4, which intersect with the O6-plane. By analyzing the tachyons on it, we reproduce the stability conditions of the baryons that are expected from the gauge theory viewpoint. The stable baryon configurations are classified systematically using K-theory. We also give a similar analysis of the flux tubes and again reproduce the results that are consistent with QCD.
理論物理学刊行会の論文
2009-12-25