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Minimal conformal technicolor and precision electroweak tests

  • Jared A. Evans
  • Jamison Galloway
  • Markus A. LutyEmail author
  • Ruggero Altair Tacchi
Open Access
Article

Abstract

We study the minimal model of conformal technicolor, an SU(2) gauge theory near a strongly coupled conformal fixed point, with conformal symmetry softly broken by technifermion mass terms. Conformal symmetry breaking triggers chiral symmetry breaking in the pattern SU(4) → Sp(4), which gives rise to a pseudo-Nambu-Goldstone boson that can act as a composite Higgs boson. The top quark is elementary, and the top and electroweak gauge loop contributions to the Higgs mass are cut off entirely by Higgs compositeness. In particular, the model requires no top partners and no “little Higgs” mechanism. A nontrivial vacuum alignment results from the interplay of the top loop and technifermion mass terms. The composite Higgs mass is completely determined by the top loop, in the sense that m h /m t is independent of the vacuum alignment and is computable by a strong-coupling calculation. There is an additional composite pseudoscalar A with mass larger than m h and suppressed direct production at LHC. We discuss the electroweak fit in this model in detail. Corrections to \( Z \to \bar{b}b \) and the T parameter from the top sector are suppressed by the enhanced Sp(4) custodial symmetry. Even assuming that the strong contribution to the S parameter is positive and usuppressed, a good electroweak fit can be obtained for v/f ≲ 0.25, where v and f are the electroweak and chiral symmetry breaking scales respectively. This requires fine tuning at the 10% level.

Keywords

Beyond Standard Model Technicolor and Composite Models 

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© The Author(s) 2010

Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.

Authors and Affiliations

  • Jared A. Evans
    • 1
  • Jamison Galloway
    • 1
  • Markus A. Luty
    • 1
    Email author
  • Ruggero Altair Tacchi
    • 1
  1. 1.Physics DepartmentUniversity of California DavisDavisU.S.A.

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