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The following table summarizes the key properties of the six quarks. Flavor quantum numbers ( isospin ( I 3 ), charm ( C ), strangeness ( S , not to be confused with spin), topness ( T ), and bottomness ( B ′)) are assigned to certain quark flavors, and denote qualities of quark-based systems and hadrons.
These lists detail all known and predicted baryons in total angular momentum J = 1 / 2 and J = 3 / 2 configurations with positive parity. [5]Baryons composed of one type of quark (uuu, ddd, ...) can exist in J = 3 / 2 configuration, but J = 1 / 2 is forbidden by the Pauli exclusion principle.
Protons, composed of two up and one down quark (uud) Neutrons, composed of two down and one up quark (ddu) Hyperons, such as the Λ, Σ, Ξ, and Ω particles, which contain one or more strange quarks, are short-lived and heavier than nucleons. Although not normally present in atomic nuclei, they can appear in short-lived hypernuclei.
Since then, proof of the top quark (1995), the tau neutrino (2000), and the Higgs boson (2012) have added further credence to the Standard Model. In addition, the Standard Model has predicted various properties of weak neutral currents and the W and Z bosons with great accuracy.
The, "f", "a", "b" and "h" mesons are not listed in the tables below and their internal structure and quark content is a matter of ongoing investigation. [6] [7] The particle described in the table above as f 0 (500) has historically been known by two other names: f 0 (600) and σ (sigma). [8]
The following table lists current measured masses and mass estimates for all the fermions, using the same scale of measure: millions of electron-volts relative to square of light speed (MeV/c 2). For example, the most accurately known quark mass is of the top quark (t) at 172.7 GeV/c 2, estimated using the on-shell scheme.
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 Eightfold Way , the successful classification scheme organizing the large number of lighter hadrons that ...
Except for the proton and neutron, all other hadrons are unstable and decay into other particles in microseconds or less. A proton is made of two up quarks and one down quark, while the neutron is made of two down quarks and one up quark. These commonly bind together into an atomic nucleus, e.g. a helium-4 nucleus is composed of two protons and ...