O(N) and USp(N) QCD from String Theory
Abstract
We propose a holographic dual of large N_c QCD with the gauge group O(N_c) and USp(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 the 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-anti-D8 pairs and an O6-anti-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 that are caused by quark bilinear condensates. We next discuss that baryons can be realized as D4-anti-D4 pairs wrapped on S^4 that 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 by using K-theory. We also give a similar analysis for the flux tubes and again reproduce the results that are consistent with QCD.
Cite
@article{arxiv.0907.2968,
title = {O(N) and USp(N) QCD from String Theory},
author = {Toshiya Imoto and Tadakatsu Sakai and Shigeki Sugimoto},
journal= {arXiv preprint arXiv:0907.2968},
year = {2011}
}
Comments
20 pages, 2 figures, v2: discussions of flux tubes clarified, references added, v3: minor changes, final version published in PTP