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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]
The strong force is described by quantum chromodynamics (QCD), a part of the Standard Model of particle physics. Mathematically, QCD is a non-abelian gauge theory based on a local (gauge) symmetry group called SU(3). The force carrier particle of the strong interaction is the gluon, a massless gauge boson.
For instance a pentaquark made of two up quarks, one down quark, one charm quark, and one charm antiquark would be denoted uudc c. The quarks are bound together by the strong force, which acts in such a way as to cancel the colour charges within the particle. In a meson, this means a quark is partnered with an antiquark with an opposite colour ...
In the 1960s, he introduced current algebra as a method of systematically exploiting symmetries to extract predictions from quark models, in the absence of reliable dynamical theory. This method led to model-independent sum rules confirmed by experiment, and provided starting points underpinning the development of the Standard Model (SM), the ...
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 ...
The Standard Model of particle physics is the theory describing three of the four known fundamental forces (electromagnetic, weak and strong interactions – excluding gravity) in the universe and classifying all known elementary particles.
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