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,
*W*s 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 *s*^{1/2} = 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].

**Technicolor**

* __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
*W*s 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.

**References**

@ __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 SL_{q}(2)],
a0901 [and strong
interactions].

@ __Other versions__: Witters ht/99 [with
fermions only]; Bilson-Thompson hp/05
[topological model,
braid group B_{3}]; Freund a0809-in
[from spinless
constituents, higher-dimensional]; Fritzsch a1010; Grossman & Robinson JHEP(11) [neutrinos as composite Dirac particles].

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