quark

quark (kwôrk): see elementary particles.

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quark

Any of a group of subatomic particles thought to be among the fundamental constituents of matter—more specifically, of protons and neutrons. The concept of the quark was first proposed by Murray Gell-Mann and George Zweig (b. 1937); its name was taken from James Joyce's novel Finnegans Wake. Quarks include all particles that interact by means of the strong force. They have mass and spin, and they obey the Pauli exclusion principle. They have never been resolved into smaller components, and they never occur alone. Their behaviour is explained by the theory of quantum chromodynamics, which provides a means of calculating their basic properties. There are six types of quarks, called up, down, strange, charm, bottom, and top. Only the up and down quarks are needed to make protons and neutrons; the others occur in heavier, unstable particles.

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quark

Physics any of a set of six hypothetical elementary particles together with their antiparticles thought to be fundamental units of all baryons and mesons but unable to exist in isolation. The magnitude of their charge is either two thirds or one third of that of the electron

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quark [kwärk]

(particle physics)

One of the hypothetical basic particles, having charges whose magnitudes are one-third or two-thirds of the electron charge, from which many of the elementary particles may, in theory, be built up; for example, nucleons may be formed from three quarks and mesons from quark-antiquark combinations; no experimental evidence for the actual existence of free quarks has been found.