Minimal Walking Models
In 2004 Francesco Sannino and Kimmo Tuominen proposed technicolor models with technifermions in higher-dimensional representations of the technicolor gauge group. They argued that these more "minimal" models required fewer flavors of technifermions in order to exhibit walking behavior, making it easier to pass precision electroweak tests.
For example, SU(2) and SU(3) gauge theories may exhibit walking with as few as two Dirac flavors of fermions in the adjoint or two-index symmetric representation. In contrast, at least eight flavors of fermions in the fundamental representation of SU(3) (and possibly SU(2) as well) are required to reach the near-conformal regime.
These results continue to be investigated by various methods, including lattice simulations discussed below, which have confirmed the near-conformal dynamics of these minimal walking models. The first comprehensive effective Lagrangian for minimal walking models, featuring a light composite Higgs, spin-one states, tree-level unitarity, and consistency with phenomenological constraints was constructed in 2007 by Foadi, Frandsen, Ryttov and Sannino.
Read more about this topic: Technicolor (physics)
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