Minimal conformal technicolor and precision electroweak tests
By Jared A. Evans, J. Galloway, M. Luty, R. Tacchi. 2010
169 citations recorded by the source corpus.
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 mh/mt 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 mh 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.
Subfields: Artificial Intelligence, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/c42a1d08f95d7d265991c95ecf81857731c48de5
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Citations in the corpus
- Composite scalar dark matter (2012, background): “Interestingly, the pattern SO(6)/SO(5) is the minimal example with a known ultraviolet completion in terms of techni-quarks [11].”
- Bounds in 4D conformal field theories with global symmetry (2010, unknown): “This in turn was needed in order to constrain the Conformal Technicolor scenario of electroweak symmetry breaking [7].”
- UV descriptions of composite Higgs models without elementary scalars (2013, background): “The questions we therefore ask here are, given a low-energy effective description based on a chiral Lagrangian, is it possible to find a well defined UV description, containing only fermions and gauge fields, such that the Higgs mass is protected by its NGB status only? And, if so, what sort of prop”
- Improved bounds for CFT’s with global symmetries (2011, background): “This in turn was needed in order to constrain the Conformal Technicolor scenario of electroweak symmetry breaking ([15–17]).”
- A pseudoscalar decaying to photon pairs in the early LHC Run 2 data (2015, unknown): “See [43–47] for previously studied examples.”
- Addressing the B-physics anomalies in a fundamental Composite Higgs model (2018, background): “[62, 72, 73] for modern realisations of this idea and for a discussion of the problems one may encounter in this approach.”