isospinn.
/ˈʌɪsə(ʊ)spɪn/, U.S. /ˈaɪsoʊˌspɪn/, /ˈaɪsəˌspɪn/ Particle Physics.
A vector quantity and associated quantum number assigned to subatomic particles and atomic nuclei to give expression to the fact that the strong force is independent of electric charge. Symbol I (or sometimes alternatively T).I is assigned on the basis of there being 2I + 1 particles in a charge mulitplet (multiplet n. 2b), each particle having the same value of I but differing in the third component of isospin, I3 (or Is) according to the charge of each particle, with the result that all the particles of the multiplet can be treated as different states of a single particle.
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isobaric spin1953
isospin1956
1956 Nucl. Physics 2 583 Preserving the Prentki-d'Espagnat assignment of iso-spin and strangeness, we can construct the following isobaric 4-spinors.
1965 H. Muirhead Physics Elem. Particles i. 14 The isospin of a system is formally similar to angular momentum but is linked to the charge states of the system.
1971 P. E. Hodgson Nucl. Reactions xix. 575 The isospin T of a nucleus is the sum of the isospins ti of its constituent nucleons.
1992 Philos. Trans. (Royal Soc.) A. 341 24 The nuclear symmetry energy..is determined by the isospin dependence of the nuclear interactions.
2004 A. Watson Quantum Quark iv. 147 If ‘pion’ is the family name isospin I = 1, then the three ‘forenames’ are pi-plus (I3 = +1), pi-zero (I3 = 0) and pi-minus (I3 = −1).
2006 P. Woit Not even Wrong v. 72 The strong interactions between nucleons..are said to have an SU(2) isospin symmetry.
This entry has been updated (OED Third Edition, December 2013; most recently modified version published online March 2022).
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n.1956