Technicolor (physics)
The term technicolor theories (TC ) are summarized in elementary particle physics extensions of the Standard Model, in which the scalar Higgs boson is not a fundamental particle, but a bound state of newly introduced fermions, so-called Techniquarks. The binding is via a newly introduced strong interaction, which has a similar structure of quantum chromodynamics ( as a non-Abelian gauge theory, Yang-Mills theory ), with new color degrees of freedom ( colors), so the name Technicolor, originally in a joking reference to the Technicolor process of the ink film.
A motive for this approach is that fundamental scalar particles are perceived as unnatural in quantum field theory by many theorists. Another motive is to find a fundamental theory that explains the parameters of the standard model ( coupling constants, mixing angles, masses). They also provide an alternative to supersymmetric theories is in the solution of the so-called hierarchy problem, which results from the in GUTs inevitable mixture ( by so-called radiative corrections at 1 - loop diagrams) to the very different scales of symmetry breaking ( electro-weak symmetry breaking and GUT- scale).
Since the breaking of the electroweak symmetry yields as a result of interaction dynamics in technicolor theories, the theory is also known as Dynamic symmetry breaking of the electroweak interaction. The term "dynamic symmetry breaking " itself is not limited to the elementary particle physics. In solid-state physics, there is for example in the superconductivity with the formation of Cooper pairs in the BCS theory a dynamic symmetry breaking. In elementary particle physics this the beginning of the 1960s in the Nambu -Jona - Lasinio model has been transferred ( by Nambu and Jona- Lasinio ), which is the model for many theories with dynamic symmetry breaking.
Technicolor theories were first introduced in the late 1970s by Leonard Susskind and Steven Weinberg.
Shortly afterwards, in order to integrate the TC gauge groups and gauge groups of the standard model in a common gauge group and to have such a theory of the interaction of the usual fermions of the standard model ( leptons, quarks ) with the Techniquarks ( with the possibility of deriving the masses and other parameters of the standard model ), Extended Technicolor (ETC) introduced by Savas Dimopoulos and Susskind and Estia Eichten and Kenneth Lane (the latter used then the name Hypercolor instead Technicolor ).
TC theories say new particles ahead that could be detected at particle accelerators such as the LHC, and also supply candidates for dark matter. But you also encounter several difficulties that arise as from the already present precision measurements of the electroweak theory. In particular, ETC theories predict Flavor - changing neutral currents (Flavor Changing Neutral Current, FCNC ), which are suppressed in the standard model and for which tight experimental bounds. Walking TC theories have been As a way back in the 1980s suggested ( by Thomas Appelquist, and others). They were examined in the 2000s and numerically in lattice QCD simulations.
Except TC theories, there are other theories that also contain composite fermions from Higgs bosons. In particular Präon models in which quarks and leptons are generally composed of more fundamental fermions, and theories of the Higgs boson as a top quark condensate ( bound state of top quark and anti- top quark ).