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Related to gluon: graviton, quark


an elementary particle that mediates, or carries, the strong, or nuclear, force. In quantum chromodynamicsquantum chromodynamics
(QCD), quantum field theory that describes the properties of the strong interactions between quarks and between protons and neutrons in the framework of quantum theory.
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 (QCD), the quantum field theoryquantum field theory,
study of the quantum mechanical interaction of elementary particles and fields. Quantum field theory applied to the understanding of electromagnetism is called quantum electrodynamics (QED), and it has proved spectacularly successful in describing the
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 of strong interactionsstrong interactions,
actions between elementary particles mediated, or carried, by gluons. They are responsible for the binding of protons and neutrons in the nucleus and interactions between quarks.
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, the interaction of quarks (to form protonsproton,
elementary particle having a single positive electrical charge and constituting the nucleus of the ordinary hydrogen atom. The positive charge of the nucleus of any atom is due to its protons.
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, neutronsneutron,
uncharged elementary particle of slightly greater mass than the proton. It was discovered by James Chadwick in 1932. The stable isotopes of all elements except hydrogen and helium contain a number of neutrons equal to or greater than the number of protons.
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, and other elementary particleselementary particles,
the most basic physical constituents of the universe. Basic Constituents of Matter

Molecules are built up from the atom, which is the basic unit of any chemical element. The atom in turn is made from the proton, neutron, and electron.
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) is described in terms of gluons—so called because they "glue" the quarks together. Gluons are massless, travel at the speed of light, and possess a property called color. Analogous to electric charge in charged particles, color is of three varieties, arbitrarily designated as red, blue, and yellow, and—analogous to positive and negative charges—three anticolor varieties. Quarks change their color as they emit and absorb gluons, and the exchange of gluons maintains proper quark color balance.

Unlike other forces, the force between quarks increases as the distance between the quarks increases. Up to distances about the diameter of a proton, quarks behave as if they were free of one another, a condition called asymptotic freedom. As the quarks move farther apart, the gluons that move between them utilize the energy that they draw from the quark's motion to create more gluons—the larger the number of gluons exchanged among quarks, the stronger the binding force. The gluons thus appear to lock the quarks inside the elementary particles, a condition called confinement. Gluons can also bind with one another to form composite particles called glueballs.

According to QCD, only colorless objects may exist in isolation. Therefore, individual gluons and individual quarks cannot exist in nature, and only indirect evidence of their existence can be detected. In 1979, compelling evidence was found when quarks were shown to emit gluons during studies of particle collisions at the German national high-energy physics laboratory in Hamburg.


See J. Diasdebens and S. Costa Ramos, ed., The Physics of Quark-Gluon Plasma (1988); F. J. Yndurain, The Theory of Quark and Gluon Interactions (1993).

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(gloo -on) See quark.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006


(particle physics)
One of eight hypothetical massless particles with spin quantum number and negative parity that mediate strong interactions between quarks.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
To put it in gluon terms that obviously connote this history,
It is the free quarks and gluons situation; [[alpha].sub.s] [right arrow] 0 occurs at high energy for the free quarks phase.
An extended amino acid chain and the water molecules H-bonded to it are just as above, a QPF being filled in by quarks, gluons, electrons and photons.
GuideViewer maintains guide colors and keeps guides locked when giving files to XPress users who do not yet own any of GLUON's guide making XTensions (including ProGrids, ProGuides and Cropster).
Calculations in the framework of lattice QCD show [16, 17] that, at the energy densities exceeding a critical value of about 1 to 1.5 GeV per [fm.sup.3], achievable at incident energies of about [square root of ([s.sub.NN])] [greater than or equal to] 5 GeV, the hadronic phase of matter disappears giving rise to the primordial high density state (QGP) whose evolution is governed by the elementary interactions of quarks and gluons. From the radius of a tube equal 1 fm and the experimental value of the density (1/N)(dN/d[eta]) for selected proton-nucleus events we have for Bjorken's energy density [18] approximately 2.0 GeV per [fm.sup.3] what is more than the critical value of the density.
Therefore, in my geometrical version of the SM, we have 3-D lepton states, 3-D hadron states, 3-D electroweak boson states, but 4-D quark states and 4-D gluon states.
The quark-gluon (qg) processes contributing in the two-jet case are shown in Figure 6 where the s, t channel contributions between the quarks and gluons are involved to produce N with l in association with two jets following the CC interactions at the N production vertex.
Still worse, in QCD at low momentum transfers ([dagger]), like in an undisturbed proton, the particles "quarks" and "gluons" cannot even be defined [9] and thus do not "exist" within the proton, even when disregarding the quantum mechanical measurement process described above.
In direct processes, the parton (gluon) a of the incident nucleus A interacts with the parton (gluon) b of another incident nucleus B by the interaction of gg [right arrow] [[eta].sub.c]g.
Called a quark gluon plasma, it's a state of matter that existed in the milliseconds after the Big Bang 13.7 billion years ago.
If lepton's and neutrino's mass terms are equal to zero in this equation then we obtain the Dirac's equation with gauge members similar to eight gluon's fields [8].
Bannur, "Strongly coupled quark gluon plasma (SCQGP)," Journal of Physics G: Nuclear and Particle Physics, vol.