composite higgs models


  • This differs from the prediction ordinary technicolor theories where new strong dynamics directly breaks the electro-weak symmetry without the need of a physical Higgs boson.

  • Within the most compelling scenarios each Standard Model particle has a partner with equal quantum numbers but heavier mass.

  • For example, for the model above with SO(5) global symmetry the coupling of the Higgs to W and Z bosons is modified as Phenomenological studies suggest     and thus at least
    a factor of a few larger than    .

  • In parallel, early composite Higgs models arose from the heavy top quark and its renormalization group infrared fixed point, which implies a strong coupling of the Higgs to
    top quarks at high energies.

  • Though naturalness requires that new particles exist with mass around a TeV which could be discovered at LHC or future experiments, nonetheless as of 2018, no direct or indirect
    signs that the Higgs or other SM particles are composite has been detected.

  • In the first type of scenario there is no a priori reason why the Higgs boson is lighter than the other composite states and moreover larger deviations from the SM are expected.

  • Partial compositeness is naturally realized in the gauge sector, where an analogous phenomenon happens quantum chromodynamics and is known as γ–ρ mixing (after the photon
    and rho meson – two particles with identical quantum numbers which engage in similar intermingling).

  • In the simplest models one finds a correlation between the Higgs mass and the mass   M   of the top partners,[14] In models with     as suggested by naturalness this indicates
    fermionic resonances with mass around   1 TeV .

  • At present, we have no idea what mass / energy scale will be reveal additional information about the Higgs boson that may shed useful light on these issues.

  • This allows to explain why this particle is lighter than the rest of the composite particles whose mass is expected from direct and indirect tests to be around a TeV or higher.

  • In particle physics, composite Higgs models (CHM) are speculative extensions of the Standard Model (SM) where the Higgs boson is a bound state of new strong interactions.

  • The fact that nature provides a single (weak isodoublet) scalar field that ostensibly uniquely generates fundamental particle masses seems incongruent with common sense.[why?]

  • Philosophically, the Higgs boson is either a composite state, built of more fundamental constituents, or it is connected to other states in nature by a symmetry such as supersymmetry
    (or some blend of these concepts).

  • New heavy partners of Standard Model particles, with SM quantum numbers and masses around a TeV 2.

  • This dimension may be related to the Fermi scale (100 GeV) that determines the strength of the weak interactions such as in β-decay, but it could be significantly smaller.

  • The more recent work on the holographic realization of CHM, which is based on the AdS/QCD correspondence, provided an explicit realization of the strongly coupled sector of
    CHM and the computation of meson masses, decay constants and the top-partner mass.

  • New contributions to flavor observables Supersymmetric models also predict that every Standard Model particle will have a heavier partner.

  • History Often referred to as “natural” composite Higgs models, CHMs are constructions that attempt to alleviate fine-tuning or “naturalness” problem of the Standard Model.

  • An approximate relation exists between mass and coupling of the composite states, In CHM one finds that deviations from the SM are proportional to where     is the electro-weak
    vacuum expectation value.

  • The new particles could be produced and detected in collider experiments if the energy of the collision exceeds their mass or could produce deviations from the SM predictions
    in “low energy observables” – results of experiments at lower energies.

  • [8] CHMs typically predict new particles with mass around a TeV (or tens of TeV as in the Little Higgs schemes) that are excitations or ingredients of the composite Higgs,
    analogous to the resonances in nuclear physics.

  • [7] Top Seesaw models have a nice geometric interpretation in theories of extra dimensions, which is most easily seen via dimensional deconstruction (the latter approach does
    away with the technical details of the geometry of the extra spatial dimension and gives a renormalizable D-4 field theory).

  • It was later realized, as with the case of Top Seesaw models described above, that this can naturally arise in five-dimensional theories, such as the Randall–Sundrum scenario
    or by dimensional deconstruction.

  • [15] This is similar to a (deconstructed) extra dimension, in which every Standard Model particle has a heavy partner(s) that can mix with it.

  • variation on technicolor theories to allow for the presence of a physical low mass Higgs boson.

  • While theorists remain busy concocting explanations, this limited insight poses a major challenge to experimental particle physics: We have no clear idea whether feasible
    accelerators might provide new useful information beyond the S.M.

  • For example, a strongly motivated representation for left-handed fermions is the (2,2) that contains particles with exotic electric charge with special experimental signatures.

  • This formed the basis of top quark condensation theories of electroweak symmetry breaking in which the Higgs boson is composite at extremely short distance scales, composed
    of a pair of top and anti-top quarks.

  • In all composite Higgs models the recently discovered Higgs boson is not an elementary particle (or point-like) but has finite size, perhaps around 10−18 meters.

  • To remedy the fine tuning problem, Chivukula, Dobrescu, Georgi and Hill[6] introduced the “Top See-Saw” model in which the composite scale is reduced to the several TeV (trillion
    electron volts, the energy scale of the LHC).

  • For fermions it is an assumption that in particular requires the existence of heavy fermions with equal quantum numbers to S.M.

  • In CHM the Higgs potential is generated by effects that explicitly break the global symmetry  G  .


Works Cited

[‘1. G. F. Giudice, Naturalness after LHC8, PoS EPS HEP2013, 163 (2013)
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3. ^ Miransky, Vladimir A.; Tanabashi, Masaharu; Yamawaki, Koichi
(1989). “Dynamical electroweak symmetry breaking with large anomalous dimension and t quark condensate”. Phys. Lett. B. 221 (177): 177. Bibcode:1989PhLB..221..177M. doi:10.1016/0370-2693(89)91494-9.
4. ^ Miransky, Vladimir A.; Tanabashi, Masaharu;
Yamawaki, Koichi (1989). “Is the t quark responsible for the mass of W and Z bosons?”. Modern Physics Letters A. 4 (11): 1043. Bibcode:1989MPLA….4.1043M. doi:10.1142/S0217732389001210.
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Manfred (1990). “Minimal dynamical symmetry breaking of the standard model”. Physical Review D. 41 (5): 1647–1660. Bibcode:1990PhRvD..41.1647B. doi:10.1103/PhysRevD.41.1647. PMID 10012522.
6. ^ Chivukula, R. Sekhar; Dobrescu, Bogdan; Georgi, Howard
& Hill, Christopher T. (1999). “Top Quark Seesaw Theory of Electroweak Symmetry Breaking”. Physical Review D. 59 (5): 075003. arXiv:hep-ph/9809470. Bibcode:1999PhRvD..59g5003C. doi:10.1103/PhysRevD.59.075003. S2CID 14908326.
7. ^ Cheng, Hsin-Chia;
Dobrescu, Bogdan A.; Gu, Jiayin (2014). “Higgs Mass from Compositeness at a Multi-TeV Scale”. JHEP. 2014 (8): 095. arXiv:1311.5928. Bibcode:2014JHEP…08..000C. doi:10.1007/JHEP08(2014)095.
8. ^ Hill, Christopher T.; Simmons, Elizabeth H. (2003).
“Strong dynamics and electroweak symmetry breaking”. Phys. Rep. 381 (4–6): 235. arXiv:hep-ph/0203079. Bibcode:2003PhR…381..235H. doi:10.1016/S0370-1573(03)00140-6. S2CID 118933166. Archived from the original on 2019-05-03. Retrieved 2019-11-17.
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K. Agashe, R. Contino and A. Pomarol, “The Minimal composite Higgs model”, Nucl. Phys. B719, 165 (2005)
10. ^ Erdmenger, Johanna; Evans, Nick; Porod, Werner; Rigatos, Konstantinos S. (2021-02-19). “Gauge/Gravity Dynamics for Composite Higgs Models
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