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quoting ohwillekeHave you come across this paper in peer reviewed Physical Review D... I'll only address this briefly as it really belongs in the Beyond the Standard Model forum, while the original question which is really just a fun way to elicit the Standard Model properties of higher generation fermions does not.

Models in which some or all of the Standard Model fundamental particles are actually composite particles made up of something more fundamental are generically called "Preon" models after terminology which, if I recall correctly, was the terminology used by Pati and Salam in their 1974 paper which was one of the earliest preon model proposals (also "Technicolor" models propose a composite substitute for the Higgs boson). I've contributed to and in several cases been the original author of many of the articles on Wikipedia related to preon models and a number of notable preon papers are cited in the footnotes to the Preon article at Wikipedia and in other articles linked to it. So far, the LHC and prior colliders have not seen any sign of compositeness in the fundamental leptons and quarks, and have placed extremely strict bonds on the energy scales at which such compositeness could arise in the context of fairly naive and straightforward versions of preon models. Nobody has found any evidence distinguishing fundamental particles from the point particle representation that they have in the Standard Model at any scale we can probe.

Also, only a pretty small minority of preon models explain more than one generation of fundamental fermions or provide any insight into how preons give rise to the masses of the fundamental particles of the Standard Model which in that analysis are actually composite.

There are also quite a few papers that explore the idea that leptons and quarks are more similar than they seem in a scheme in which leptons are possible because there are really four colors rather than three colors, which one of those colors, or certain combinations of those colors, giving rise to leptons that don't interact via the strong force rather than quarks (in much the same way that nobel gases are chemically inert despite being composite particles made up of things that do interact chemically when found in other configurations). Indeed, Pati and Salam's original 1974 preon paper advanced this hypothesis. The paper was Pati, J.C.; Salam, A. (1974). "Lepton number as the fourth "color"".Physical Review D.10: 275–289.

I am not aware of any peon models that specifically looks at bonds in the nature of "string-like excitations of the superconducting Higgs vacuum" and the connection between string excitation modes and particular fundamental particles in the Standard Model is much less direct and determinate than popularizations of string theory have implied.

The nuclear force holding nucleons together is established to be a residual force derived from the strong force carried by gluons that binds quarks together, and no one is publishing alternatives to this (i.e. basically QCD which is part of the Standard Model) although some physicists who have proposed preon models have considered the possibility that gluons may actually be composite bosons which are a residual force of the force that binds preons together.

http://www.sciencedirect.com/science/article/pii/0370269379906671

or

http://feynman.phy.ulaval.ca/marleau/pp/10preons/user/image/subquark-model-of-leptons-and-quarks.pdf

I have the former paper written in 1979 that mentioned the "string-like excitations of the superconducting Higgs vacuum". So 37 years later, has LHC or other papers put constraints on all it said?? Quoting the relevant passages:

"Unlike in the Pati-Salam scheme, there are no exotic gluons strongly coupling fundamental hadrons with leptons. The proton is predicted to be absolutely stable, therefore. Also, baryon number and lepton number L = ne + nu + nr + n(omega) + nk are separately conserved. Two new heavy leptons are predicted: omega- + k-. They should appear in the electron positron annihilation reactions: e+ + e- = omega+ + omega-, e+ + e- = k+ + k-.

Non-abelian generations of the Nielsen-Olesen model [4], providing permanent confinement of quarks and saturation of quark forces in zerotriality states, are very attractive in the context of a composite quark theory. The condition for topologically distinct Nielsen-Olesen vortices and Dirac monopoles to exist such that the former cannot be transformed into one another by continuous gauge transformations is that the global gauge group should be multiply connected [5]. If this group is SU(9)/Z9 (small letter 9), where the cylic group

Z9= (I9,vI9, v^2I9,...,v^8I9) (v=exp (2pi(I)/9)) [Cube137 note: 9 is small letter bottom since I don't know how to type it ]

is the centre of SU(9), then nine distinct vortices exist, since SU(9)/Z9 is 9-fold connected. One corresponds to the ground state of the vacuum and consists of no vortex; the other eight correspond to non-equivalent magnetic monopoles of monopole moment g0,2g0,... , 8g0 (g0=1/2e). This is because, with the Higgs field belonging to an adjoint representation of SU(9), single-valuedness modulo 2pi/9 of its phase implies that vortex flus (and magnetic charge, there) is defined only modulo (9) (in Dirac Units). Thus nine and only nine SU(9) monopoles form a magnetically neutral system when embedded in a superconducting Higgs vacuum and bound by Nielsen-Olesen vortices. Similary for three SU(3) monopoles in a vacuum with broken SU(3) symmetry. Omegons are bound in quarks by three supergluon octets of SU(3). With omegons as SU(9) monopoles, a neutral system of nine monopoles can cluster in three groups of three, bound internally and externally by Y-shaped strings that are connected via vortex bifurcations. In this way, the Meissner effect would confine both omegons inside quarks and quarks in hadrons. Identification of quarks as clusters of three SU(9) monopoles guarantees zero triality for bound states of quarks. This empirical rule is a dynamical consequence of an SU(9) vacuum, which confines fermions with magnetic charge (omegons) but not fermions with zero magnetic charge (leptons). In this scheme, mesons are quark-antiquark pairs, joind by three strings, not by one."

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# B Preon quark models excluded by LHC

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