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In particle physics, a Higgsless model is a model that does not involve the Higgs boson or in which the Higgs field is not dynamic. Such models must employ a different mechanism of mass generation, electroweak symmetry breaking and unitarity.

In the years since the Higgs mechanism was first described, there have been several alternatives proposed. Some alternative mechanisms use strongly interacting dynamics to produce a vacuum expectation value that breaks electroweak symmetry. A partial list of these alternative mechanisms includes:

• Technicolor models break electroweak symmetry through new gauge interactions, which were originally modeled on quantum chromodynamics.
• Extra-dimensional Higgsless models use the fifth component of the gauge fields to play the role of the Higgs fields. It is possible to produce electroweak symmetry breaking by imposing certain boundary conditions on the extra dimensional fields, increasing the unitarity breakdown scale up to the energy scale of the extra dimension. Through the AdS/QCD correspondence this model can be related to technicolor models and to "UnHiggs" models in which the Higgs field is of unparticle nature.
• Models of composite W and Z vector bosons.
• Top quark condensate.
• "Unitary Weyl gauge". In the λ→0 limit the sigma model is scale invariant, and if one further adds a suitable gravitational term to the action, the theory becomes locally scale invariant (i.e. Weyl invariant). Weyl transformations act multiplicatively on the Higgs field, so one can fix the Weyl gauge by requiring that the Higgs field to be constant.
• Asymptotic safety of some nonlinear sigma models.
• "Regular Charge Monopole Theory" by Eliyahu Comay.
• Ribbon model of Standard Model particles by Sundance Bilson-Thompson, based in braid theory and compatible with loop quantum gravity and similar theories. This model not only explains mass but leads to an interpretation of electric charge as a topological quantity (twists carried on the individual ribbons) and colour charge as modes of twisting.
• Higgs-free symmetry breaking from critical behavior near dimension four: derives the gauge structure of electroweak theory and the hierarchical pattern of particle masses and couplings near the Wilson-Fisher attractor of Renormalization Group flow. In addition, it recovers the numerical value of the cosmological constant from arguments related to dimensional regularization of Yang-Mills theory.

References

1. Steven Weinberg (1976), "Implications of dynamical symmetry breaking", Physical Review, D13 (4): 974–996, Bibcode:1976PhRvD..13..974W, doi:10.1103/PhysRevD.13.974.
   S. Weinberg (1979), "Implications of dynamical symmetry breaking: An addendum", Physical Review, D19 (4): 1277–1280, Bibcode:1979PhRvD..19.1277W, doi:10.1103/PhysRevD.19.1277.
2. Leonard Susskind (1979), "Dynamics of spontaneous symmetry breaking in the Weinberg-Salam theory", Physical Review, D20 (10): 2619–2625, Bibcode:1979PhRvD..20.2619S, doi:10.1103/PhysRevD.20.2619.
3. Csaki, C.; Grojean, C.; Pilo, L.; Terning, J. (2004), "Towards a realistic model of Higgsless electroweak symmetry breaking", Physical Review Letters, 92 (10): 101802, arXiv:hep-ph/0308038, Bibcode:2004PhRvL..92j1802C, doi:10.1103/PhysRevLett.92.101802, PMID 15089195
4. Csaki, C.; Grojean, C.; Pilo, L.; Terning, J.; Terning, John (2004), "Gauge theories on an interval: Unitarity without a Higgs", Physical Review D, 69 (5): 055006, arXiv:hep-ph/0305237, Bibcode:2004PhRvD..69e5006C, doi:10.1103/PhysRevD.69.055006
5. Calmet, X.; Deshpande, N. G.; He, X. G.; Hsu, S. D. H. (2008), "Invisible Higgs boson, continuous mass fields and unHiggs mechanism", Physical Review D, 79 (5): 055021, arXiv:0810.2155, Bibcode:2009PhRvD..79e5021C, doi:10.1103/PhysRevD.79.055021
6. Abbott, L. F.; Farhi, E. (1981), "Are the Weak Interactions Strong?", Physics Letters B, 101 (1–2): 69, Bibcode:1981PhLB..101...69A, doi:10.1016/0370-2693(81)90492-5
7. Pawlowski, M.; Raczka, R. (1994), "A Unified Conformal Model for Fundamental Interactions without Dynamical Higgs Field", Foundations of Physics, 24 (9): 1305–1327, arXiv:hep-th/9407137, Bibcode:1994FoPh...24.1305P, doi:10.1007/BF02148570
8. Codello, A.; Percacci, R. (2008), "Fixed Points of Nonlinear Sigma Models in d>2", Physics Letters B, 672 (3): 280–283, arXiv:hep-th/0810.0715, Bibcode:2009PhLB..672..280C, doi:10.1016/j.physletb.2009.01.032 {{citation}}: Check |arxiv= value (help)
9. Bilson-Thompson, Sundance O.; Markopoulou, Fotini; Smolin, Lee (2007), "Quantum gravity and the standard model", Class. Quantum Grav., 24 (16): 3975–3993, arXiv:hep-th/0603022, Bibcode:2007CQGra..24.3975B, doi:10.1088/0264-9381/24/16/002.
10. Goldfain, Ervin. PSTJ. 2 (4): 523–534 http://www.prespacetime.com/index.php/pst/article/viewFile/175/183. {{cite journal}}: Missing or empty |title= (help)

External links

• Higgsless model on arxiv.org

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