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quantum chromodynamics (QCD)
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(Topic)
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QCD or Quantum chromodynamics is the advanced, standard mathematical and quantum
physics treatment, or theory, of strong force or nuclear interactions such as those among
quarks and gluons, partons, ‘Yukawa’ mesons, and so on, with an intrinsic threefold
symmetry for RGB quarks (or ‘eightfold-way’ diagrams resulting from representations of the
quantum group SU(3) first reported by the US Nobel Laureate Gell-Mann and others.
This is not only a rather ‘colorful’ theory (as its name suggests) but also a very highly
formalized, mathematical one that affords major simplifications by postulating intrinsic
symmetries of magnetic–like ‘color’, ‘flavor’, ‘strangeness’ and top/down quark (and
anti-quark) intrinsic properties, each time involving three color charges. Single quarks, such
as the u or d ones have however never been observed, with the proton and neutron
‘consisting of’ three such quarks with a resulting ‘white’ color, or charge colorless proton and
neutron, as well as stable ‘white’ nuclei ‘consisting of’ the latter two quantum particles,
dynamically confined by the very short range, nuclear strong interactions. The quark
interactions are mediated by gluons–as well as their exchange– and the latter also carry
charge color–but unlike the photons that mediate the electromagnetic interactions in
QED– gluons have multiple interactions with each other leading to major computational
difficulties in QCD, that are not encountered in QED. Major obstacles in QCD computations
of observable nuclear (quantum) eigenvalues are therefore encountered in attempting
approximate, perturbative approaches that work extremely well for electromagentic interactions
(governed by the charge U(1) symmetry group), for example with Richard Feynman’s
approach in QED. Electro-weak (QEW) interactions were successfully approached in
QED–like fashion but with quantum field carriers that are–unlike the photon–massive,
and therefore the electro-weak interactions have limited range, unlike the photons of
zero mass at rest. Thus, QCD and QED are more than just ‘one pole apart’, as U(1)
and SU(3) are very different group symmetries. This makes obvious the need for more
fundamental, or extended quantum symmetries, such as those afforded by either several
larger groups such as U(1) × SU(2) × SU(3), or by spontaneously broken, multiple (or
localized) symmetries of a less restrictive kind present in quantum groupoids, such as for
example in weak Hopf algebra representations, locally compact groupoid Glc, unitary
representations, and so on, to the higher dimensional (quantum) symmetries of quantum double
groupoids, quantum double algebroids, quantum categories/ supercategories and/or
quantum supersymmetry superalgebras (or graded ‘Lie’ algebras, see- for example- the QFT
books by Weinberg (1995, 2003) superalgebroids in quantum gravity, or in QCD of the
extremely hot, very early, physical Universe, extremely close to the time of the ‘Big
Bang’.
"quantum chromodynamics (QCD)" is owned by bci1.(view preamble)
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See Also: overview of the content of PlanetPhysics, Elementary particles topic
| Also defines: |
nuclear forces, quarks, gluons, flavor, Yukawa mesons, Yukawa nuclear potential, QCD, gluon flux, quark-gluon plasma, quark-antiquark pair, strangeness, color charges, extended quantum symmetries |
| Keywords: |
nuclear forces, quarks, gluons, flavor, Yukawa mesons, Yukawa nuclear potential, QCD, gluon flux, quark-gluon plasma, quark-antiquark pair, strangeness, color charges, extended quantum symmetries |
Cross-references: physical Universe, quantum gravity, superalgebroids, QFT, Lie algebras, supersymmetry superalgebras, supercategories, quantum categories, double algebroids, quantum double groupoids, locally compact groupoid, weak Hopf algebra, quantum groupoids, mass, quantum field, symmetry group, work, observable, computations, QED, strong interactions, quantum particles, charge, neutron, anti-quark, quantum group, representations, diagrams, partons, nuclear interactions, force
There are 36 references to this object.
This is version 2 of quantum chromodynamics (QCD), born on 2009-03-03, modified 2009-03-03.
Object id is 568, canonical name is QuantumChromodynamicsQCD.
Accessed 10750 times total.
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Pending Errata and Addenda
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