Composite or Pre-Quark Models  

In General > s.a. Composite Systems [general theory]; Singletons.
* Idea and motivation: Quarks and leptons are composite particles; If true, this could determine their mass spectrum; Not to be confused with parton models of hadrons, which are one level up.
* Main difficulties: 1993, Their complexity and little predictive power; The models seem to raise as many problems as they solve, and are not too viable.
* Status: 2016, The idea isn't entirely dead; Though the surviving models aren't presently particularly popular, some variants are still viable.
* Various kinds: They may include bosons and fermions, fermions only, or bosons and monopoles (in order to make fermionic bound states); Some of the main examples are technicolor and
- Preons: 3 families of 3 preons + antiparticles (1974; & Jogesh C Pati and A Salam);
- Rishons: 2 particles, T and V, + antiparticles, which interact because of hypercolor charge (1979; & H Harari).

Phenomenology > s.a. experiments in physics.
* Constraints: The models have to predict the gyromagnetic ratios, contact interactions and rare processes (model dependent constraint); From these, we can assume the energy scale of compositeness to be Λ > 1 TeV.
* And other particles: In addition to quarks and leptons, the Higgs, Ws and the Z could be composite, but the photons and gluons may not, since they are associated with unbroken local gauge groups.
* Possible evidence? CDF collaboration at Fermilab, F Abe et al "Inclusive cross section in pbar-p collisions at s1/2 = 1.8 TeV" pr 24.01.1996; Some initial skepticism in the community, by 09.1996 standard model explanation seemed sufficient; In 12.1996, CDF reported that quarks seem to have no internal structure down to 10–19 m.
@ References: Burdyuzha et al AIP(99)ap [and cosmology]; Hansson & Sandin PLB(05)ap/04, Horvath ASS(07)ap [preon stars]; Joglekar IJTP(08)-a0704 [and causality]; Kumar et al JHEP(09) [top quark, at colliders].

* Idea: Technicolor models are a type of composite models, which include "technifermions" interacting via a "technicolor" strong gauge interaction that generates dynamical symmetry breaking and binds them into technicolor-singlet "techni-hadrons"; The techni-analogs of pions play the role of composite Higgs scalars that are swallowed up to give mass to the Ws and Z, while other technihadrons appear as physical particles.
* Farhi-Susskind model: It has gauge group SU(4) ⊗ SU(3) ⊗ SU(2) ⊗ U(1).
* 2004: The theory works fairly well, but it disagrees with some precision electroweak measurements, unless one goes to some corner of parameter space, and most people do not consider it a viable theory.
@ General references: Ellis et al pr(80); Sikivie pr(80); Farhi & Susskind PRP(81); Kaul RMP(83); Appelquist et al PRL(97)hp; Zubkov MPLA(10) [infinite continuation of the Farhi-Susskind model]; Andersen et al EPJP(11)-a1104 [pedagogical introduction].
@ Phenomenology and searches: Abazov et al PRL(07) [exclusion of a set of model parameters]; Järvinen et al PRD(10) [gravitational waves from the electroweak phase transition]; Vecchi JHEP(11)-a1007 [dynamical electroweak symmetry breaking].
> Online resources: see Wikipedia page.

@ General: Rajeev PLB(82); Harari SA(83)apr; Lyons PPNP(83); Joohan's notes 83; Greenberg PT(85)sep, AS(88); D'Souza & Kalman 92; Morpurgo RNC(99); Combescot et al PRP(08) [composite particles in general].
@ Preons: Bandos AIP(05)ht [BPS, twistor approach]; Das & Laperashvili PRD(06)hp [superstring-inspired]; Grover et al CQG(07)ht/06; Bandos & de Azcárraga FdP(07)ht-conf [BPS preons in M-theory]; Figueroa-O'Farrill et al CQG(07)-a0705 [in 4D and 5D supergravities]; Mongan a0801 [wrapped preon model based on holography]; Finkelstein IJMPA(09)-a0806 [and representations of the quantum algebra SLq(2)], a0901 [and strong interactions].
@ Other versions: Witters ht/99 [with fermions only]; Bilson-Thompson hp/05 [topological model, braid group B3]; Freund a0809-in [from spinless constituents, higher-dimensional]; Fritzsch a1010; Grossman & Robinson JHEP(11) [neutrinos as composite Dirac particles].

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