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In particle physics, the quark model is a classification scheme for hadrons in terms of their valence quarks—the quarks and antiquarks that give rise to the quantum numbers of the hadrons. The quark model underlies "flavor SU(3)" , or the Eightfold Way , the successful classification scheme organizing the large number of lighter hadrons that ...
The discovery finally convinced the physics community of the quark model's validity. [35] In the following years a number of suggestions appeared for extending the quark model to six quarks. Of these, the 1975 paper by Haim Harari [41] was the first to coin the terms top and bottom for the additional quarks. [42]
Zweig called the elementary particles "aces" while Gell-Mann called them "quarks"; the theory came to be called the quark model. [5] The strong attraction between nucleons was the side-effect of a more fundamental force that bound the quarks together into protons and neutrons.
The definition of "particle" in relativistic field theory is not self-evident, because if you try to determine the position so that the uncertainty is less than the compton wavelength, the uncertainty in energy is large enough to produce more particles and antiparticles of the same type from the vacuum. This means that the notion of a single ...
According to the Standard Model of particle physics, a subatomic particle can be either a composite particle, which is composed of other particles (for example, a baryon, like a proton or a neutron, composed of three quarks; or a meson, composed of two quarks), or an elementary particle, which is not composed of other particles (for example ...
According to the quark model, [8] the properties of hadrons are primarily determined by their so-called valence quarks. For example, a proton is composed of two up quarks (each with electric charge + + 2 ⁄ 3, for a total of + 4 ⁄ 3 together) and one down quark (with electric charge − + 1 ⁄ 3). Adding these together yields the proton ...
For example, the up quark has T 3 = + + 1 / 2 and the down quark has T 3 = − + 1 / 2 . A quark never decays through the weak interaction into a quark of the same T 3: Quarks with a T 3 of + + 1 / 2 only decay into quarks with a T 3 of − + 1 / 2 and conversely. π + decay through the weak interaction
The Standard Model is widely considered to be a provisional theory rather than a truly fundamental one, however, since it is not known if it is compatible with Einstein's general relativity. There may be hypothetical elementary particles not described by the Standard Model, such as the graviton , the particle that would carry the gravitational ...