Hypercharge

In particle physics, the hypercharge (a portmanteau of hyperonic and charge) Y of a particle is a quantum number conserved under the strong interaction. The concept of hypercharge combines and unifies isospin and flavour into a single charge operator. The hypercharge is useful to classify hadrons; the similarly named weak hypercharge has an analogous role in the electroweak interaction.SU(3) singlet weight diagram, where Y is hypercharge and I3 is the third component of isospin.SU(3) triplet weight diagramSU(3) septet, octet, and nonet weight diagram Note similarity with both charts on the right. The number used to describe the weight diagram depends on whether the particle(s) occupying the center of the diagram have one, two, or three distinct names.Mesons of spin 0 form a nonet. K: kaon, π: pion, η: eta meson.The octet of light spin-1/2 baryons described in SU(3). n: neutron, p: proton, Λ: Lambda baryon, Σ: Sigma baryon, Ξ: Xi baryon.SU(3) decuplet weight diagram Note similarity with chart on the right.A combination of three up, down or strange quarks with a total spin of 3/2 form the so-called baryon decuplet. The lower six are hyperons. S: strangeness, Q: electric charge. In particle physics, the hypercharge (a portmanteau of hyperonic and charge) Y of a particle is a quantum number conserved under the strong interaction. The concept of hypercharge combines and unifies isospin and flavour into a single charge operator. The hypercharge is useful to classify hadrons; the similarly named weak hypercharge has an analogous role in the electroweak interaction. Hypercharge is one of two quantum numbers of the SU(3) model of hadrons, alongside isospin I3. The isospin alone is sufficient for two quark flavours—namely, u and d—whereas presently six flavours of quarks are known. SU(3) weight diagrams (see below) are 2-dimensional with the coordinates referring to two quantum numbers, I3 (also known as Iz), which is the z-component of isospin and Y, which is the hypercharge (the sum of strangeness S, charm C, bottomness B′, topness T, and baryon number B). Mathematically, hypercharge is