particle physics Particle physics or high-energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the s ...

, the Sakata model of hadrons was a precursor to the

quark model 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 Eig ...

. It proposed that the

proton A proton is a stable subatomic particle, symbol , Hydron (chemistry), H+, or 1H+ with a positive electric charge of +1 ''e'' (elementary charge). Its mass is slightly less than the mass of a neutron and approximately times the mass of an e ...

neutron The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The Discovery of the neutron, neutron was discovered by James Chadwick in 1932, leading to the discovery of nucle ...

, and Lambda baryon were elementary particles (sometimes referred to as sakatons ), and that all other known hadrons were made of them. The model was proposed by Shoichi Sakata in 1956. The model was successful in explaining many features of hadrons, but was supplanted by the quark model as the understanding of hadrons progressed.

Overview

The success of the Sakata model is due to the fact that there is a correspondence between the

, and Lambda baryon, and the up, down, and

strange quark The strange quark or s quark (from its symbol, s) is the third lightest of all quarks, a type of elementary particle. Strange quarks are found in subatomic particles called hadrons. Examples of hadrons containing strange quarks include kaons (), ...

s. The proton contains two up quarks and a down quark, the neutron contains one up quark and two down quarks, while the Lambda baryon contains one up quark, one down quark, and one strange quark. That is, each of these baryons is made of one up and one down quark, and an additional quark: up for the proton, down for the neutron, and strange for the Lambda baryon. Because of this correspondence to the up, down, and strange quarks, the Sakata model has the same

SU(3) In mathematics, the special unitary group of degree , denoted , is the Lie group of unitary matrices with determinant 1. The matrices of the more general unitary group may have complex determinants with absolute value 1, rather than real 1 i ...

symmetry as the quark model, and can reproduce the flavour quantum numbers of all hadrons made of up, down and strange quarks. Because the

charm quark The charm quark, charmed quark, or c quark is an elementary particle found in composite subatomic particles called hadrons such as the J/psi meson and the charmed baryons created in particle accelerator collisions. Several bosons, including th ...

was not discovered until 1974, the Sakata model remained a staple of particle physics for some time after the quark model had been proposed.

References

{{reflist, 2 Hadrons

Overview

See also

References