Orientifold theory dynamics and symmetry breaking

We show that it is possible to construct explicit models of electroweak symmetry breaking in which the number of techniflavors needed to enter the conformal phase of the theory is small and weakly dependent on the number of technicolors. Surprisingly, the minimal model with just two (techni)flavors, together with a suitable gauge dynamics, can be made almost conformal. The theories we consider are generalizations of orientifold-type gauge theories, in which the fermions are in either two-index symmetric or antisymmetric representation of the gauge group, as the underlying dynamics responsible for the spontaneous breaking of the electroweak symmetry. We first study their phase diagram and use the fact that specific sectors of these theories can be mapped into supersymmetric Yang-Mills theory to strengthen our results. This correspondence allows us also to have information on part of the nonperturbative spectrum. We propose and investigate some explicit models while briefly exploring relevant phenomenological consequences. Our theories can not only be tested at the next collider experiments but, due to their simple structure, can also be studied via current lattice simulations. © 2005 The American Physical Society.