isospin multiplet

isospin multiplet

[′ī·sə‚spin ′məl·tə·plət]
(particle physics)
A collection of elementary particles which have approximately the same mass and the same quantum numbers except for charge, but have a sequence of charge values, (Y /2) -I, (Y /2) -I + 1, …, (Y /2) + I times the proton charge, where Y is an integer known as the hypercharge, and I is an integer or half-integer known as the isospin; examples are the pions (Y = 0, I = 1) and the nucleons (Y = 1, I = 1/2). Also known as charge multiplet; particle multiplet.
References in periodicals archive ?
In transitions happening inside the same isospin multiplet ([J.sup.[pi]] [right arrow] [J.sup.[pi]], J [not equal to] 0) both the vector and axial form factors contribute and in this case the nuclear matrix element ME([E.sub.x]) can be written as
Thus, like spin multiplets of a quantum state, one combines corresponding states of nuclear isobars in an isospin multiplet. For example, the ground state of the [sup.14]C, [sup.14]O and the [J.sup.[pi]] = [0.sup.+] excited state of [sup.14]N are members of an isospin triplet.
(Here, like in the spin case, M, m denote the eigenvalue of [T.sub.z], [t.sub.z], respectively.) The issue to be examined is the structure of the isospin multiplet of the four baryons:
The data confirms the similarity between members of an isospin multiplet. Thus, for example, the mass difference between the [[DELTA].sup.0] and [[DELTA].sup.++] baryons is less than 3 MeV [8], whereas the mass difference between the [DELTA] multiplet and the nucleons is about 300 MeV.