Large-N and Vacuum Alignment in Topcolor Models

Abstract

Topcolor and topcolor-assisted technicolor provide examples of dynamical electroweak symmetry breaking which include top-condensation, thereby naturally incorporating a heavy top quark. In this note we discuss the roles of the Nambu-Jona-Lasinio (NJL) and large-N approximations often used in phenomenological analyses of these models. We show that, in order to provide for top-condensation but not bottom-condensation, the top-color coupling must be adjusted to equal the critical value for chiral symmetry breaking up to O(1/N) in any theory in which the isospin-violating ``tilting'' interaction is a U(1) gauge interaction. A consequence of these considerations is that the potentially dangerous ``bottom-pions'' are naturally light. We also show that the contributions to rho-1 previously estimated are of leading-order in N, are not included in the usual NJL analysis, and are the result of ``vacuum-alignment''.

12 pages, 5 epsf figures

References in corpus (1)

• Model-independent Constraints on Topcolor from $R_b$

Cited by in corpus (12)

• Strong Dynamics and Electroweak Symmetry Breaking
• Top Quark Seesaw Theory of Electroweak Symmetry Breaking
• Top quark condensation
• Probing Higgs Bosons with Large Bottom Yukawa Coupling at Hadron Colliders
• Constraints on Topcolor Assisted Technicolor Models from Vertex Corrections
• Electroweak symmetry breaking as a consequence of compact dimensions
• Minimal Composite Higgs Model with Light Bosons
• Top condensation as a motivated explanation of the top forward-backward asymmetry
• The Planck Scale from Top Condensation
• Discovering Strong Top Dynamics at the LHC
• Effective Field Theory of Vacuum Tilting
• Dynamically broken Topcolor at Large-N