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While the quark model is derivable from the theory of quantum chromodynamics, the structure of hadrons is more complicated than this model allows. The full quantum mechanical wavefunction of any hadron must include virtual quark pairs as well as virtual gluons, and allows for a variety of mixings. There may be hadrons which lie outside the ...
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.
[b] In a pentaquark, the colours also need to cancel out, and the only feasible combination is to have one quark with one colour (e.g. red), one quark with a second colour (e.g. green), two quarks with the third colour (e.g. blue), and one antiquark to counteract the surplus colour (e.g. antiblue). [11]
The virtual photon (γ *) knocks a quark (q) out of the hadron. In particle physics , deep inelastic scattering is the name given to a process used to probe the insides of hadrons (particularly the baryons , such as protons and neutrons ), using electrons , muons and neutrinos .
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 ...
) which decays into a down quark (d) and a down antiquark (d). In particle physics, a kaon, also called a K meson and denoted K, [a] is any of a group of four mesons distinguished by a quantum number called strangeness. In the quark model they are understood to be bound states of a strange quark (or antiquark) and an up or down antiquark (or ...
In 1964, Gell-Mann [4] and George Zweig [5] [6] (independently of each other) proposed the quark model, then consisting only of up, down, and strange quarks. [7] However, while the quark model explained the Eightfold Way, no direct evidence of the existence of quarks was found until 1968 at the Stanford Linear Accelerator Center.