History of Quark

	Revision 14 . . (edit) September 26, 2001 8:05 am by (logged).253.100.xxx
	Revision 13 . . September 26, 2001 12:03 am by (logged).104.137.xxx
	Revision 12 . . (edit) September 4, 2001 12:22 pm by AxelBoldt [*link]

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Difference (from prior major revision) (minor diff, author diff)

Changed: 2c2

Protons and neutrons are well-known examples of particles that are composed of quarks.

Protons and neutrons are well-known examples of particles that are composed of quarks. Objects made up of quarks are known as hadrons?.

Changed: 4c4

Quarks never exist alone but only in groups. Quarks are differentiated from leptons, the other family of elemental particles, by electric charge. Leptons? have integral charge (0 or -1) while quarks have 2/3 or -1/3 charge.

Quarks never exist alone but only in groups. Quarks are differentiated from leptons, the other family of elemental particles, by electric charge. Leptons? have integral charge (+1, 0 or -1) while quarks have +2/3 or -1/3 charge (antiquarks have -2/3 or +1/3 charge).

Changed: 17c17

A proton is made of two up quarks and one down, giving a charge of +1. A neutron is made of two down

A proton is made of two up quarks and one down, giving a charge of +1. A neutron is made of two down

Changed: 31c31

quarks together forming a baryon, and a "secondary" effect of

quarks together forming a baryon, or meson, and a "secondary" effect of

Changed: 34,35c34

Antiquarks come in antired, antiblue and antigreen, and there is a second kind of particle composed by quarks called mesons. Mesons are formed by quark-antiquark configurations

There is a second kind of particle composed by quarks called mesons. Mesons are formed by quark-antiquark configurations

Added: 37a37,38

Due to the extremely strong nature of the [strong force]? (hence its name), quarks are never found free. They are always bound into baryons, mesons, or nuclei. When we try to separate quarks in a meson or baryon, as happens in [particle accelerators]?, the strong force actually becomes stronger as they get farter apart. At some point it is more energetically favorable to create two more quarks to cancel out the increasing force, and nature pops two new quarks out of the vacuum. This process is called hadronization? or fragmentation, and is one of the least understood processes in particle physics. As a result of fragmentation, when quarks are produced in particle accelerators, instead of seeing the individual quarks in detectors, scientists see "jets" of many color-neutral particles (mesons and baryons), clustered together.