Quarks- any group of subatomic particles believed to be among the basic Quarks are believed to be the fundamental constituents of matter, and have no apparent structure. They are the particles that make up protons andneutrons, which make up the nucleus of atoms. Also, particles that interact bymeans of the strong force, the force that holds parts of the nucleus together,are explained in terms of quarks. Other baryons are explained in terms ofquarks(1985 Quarks).Quarks have mass and exhibit spin, the type of intrinsic angularmomentum corresponding to rotation around an axis, equal to half the basicquantum mechanical unit of angular momentum, obeying Pauli's exclusion principle. This principle that no two particles having half integral spin can exist in thesame quantum state(1985 Quarks).Quarks always occur in combination with other quarks, they never occuralone. Physicists have attempted to knock a single quark free from a groupusing a particle accelerator, but have failed. Mesons contain a quark and anantiquark, up, down, and strange, while baryons contain three quarksdistinguished by flavours. Each has a charge that is a fraction of that of anelectron. Up and down quarks make up protons and neutrons, and can be observedin ordinary matter. Strange quarks can be observed in omega-minus and othershort lived subatomic particles which play on part in ordinary matter(1985Quarks).The interpretation of quarks as physical entities poses two problems.First, sometimes two or three identical quarks have to be in the same quantumstate which, because they have to have half integral spin, violates Pauli'sexclusion principal. Second, quarks appear to not be able to be separated fromthe particles they make up. Although the force holding the quarks together isstrong it is improbable that it could withstand bombardment from high energy andneutrinions in a particle accelorator(1985 Quarks).Quantum chromodynamics(QCD) ascribes colours red, g...
