Isospin in the context of "Sigma baryon"

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 (K), strange D mesons (D
_s), sigma baryons (Σ), and other strange particles.

According to the IUPAP, the symbol s is the official name, while "strange" is to be considered only as a mnemonic. The name sideways has also been used because the s quark (but also the other three remaining quarks) has an I₃ value of 0 while the u ("up") and d ("down") quarks have values of +⁠1/2⁠ and −⁠1/2⁠ respectively.

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 provides a single charge operator that accounts for properties of isospin, electric charge, and flavour. The hypercharge is useful to classify hadrons; the similarly named weak hypercharge has an analogous role in the electroweak interaction.

In particle physics, weak isospin is a quantum number relating to the electrically charged part of the weak interaction: Particles with half-integer weak isospin can interact with the W
bosons; particles with zero weak isospin do not.Weak isospin is a construct parallel to the idea of isospin under the strong interaction. Weak isospin is usually given the symbol T or I, with the third component written as T₃ or I₃ . T₃ is more important than T; typically "weak isospin" is used as short form of the proper term "3rd component of weak isospin". It can be understood as the eigenvalue of a charge operator.

In particle physics, exotic mesons are mesons that have quantum numbers not possible in the quark model; some proposals for non-standard quark model mesons could be:

All exotic mesons are classed as mesons because they are hadrons and carry zero baryon number. Of these, glueballs must be flavor singlets – that is, must have zero isospin, strangeness, charm, bottomness, and topness. Like all particle states, exotic mesons are specified by the quantum numbers which label representations of the Poincaré symmetry, q.e., by the mass (enclosed in parentheses), and by J, where J is the angular momentum, P is the intrinsic parity, and C is the charge conjugation parity; One also often specifies the isospin I of the meson. Typically, every quark model meson comes in SU(3) flavor nonet: an octet and an associated flavor singlet. A glueball shows up as an extra (supernumerary) particle outside the nonet.

In particle physics, a rho meson is a short-lived hadronic particle that is an isospin triplet whose three states are denoted as ρ
, ρ
and ρ
. Along with pions and omega mesons, the rho meson carries the nuclear force within the atomic nucleus. After the octet consisting of the pions, kaons, and eta meson, the rho mesons are the lightest strongly interacting particle, with a mass of about 775 MeV for all three states.

The rho mesons have a very short lifetime and their decay width is about 145 MeV; because that is large compared with the mass, the resonance width measurably deviates from a Breit–Wigner form. The principal decay route of the rho mesons is to a pair of pions with a branching rate of 99.9% (however, all neutral pions is forbidden).