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
+ their 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];
Aguilar et al a1802 [radiative corrections].

@ __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];
Finkelstein a1809 [and Schwinger dyons].

@ __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].

> __Related topics__:
see relativistic particles [classical description].

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