Hidden QCD in chiral gauge theories

The 't Hooft and Corrigan-Ramond limits of massless one-flavor QCD consider the two Weyl fermions to be, respectively, in the fundamental representation and the two index antisymmetric representation of the gauge group. We introduce a limit in which one of the two Weyl fermions is in the fundamental representation and the other in the two index antisymmetric representation of a generic SU(N) gauge group. This theory is chiral and to avoid gauge anomalies a more involved chiral theory is needed. This is the generalized Georgi-Glashow model with one vectorlike fermion. We show that there is an interesting phase in which the considered chiral gauge theory, for any N, Higgses via a bilinear condensate: The gauge interactions break spontaneously to ordinary massless one-flavor SU(3) QCD. The additional elementary fermionic matter is uncharged under this SU(3) gauge theory. It is also seen that when the number of colors reduce to three it is exactly this hidden QCD which is revealed. © 2006 The American Physical Society.