baryon - Background, Baryonic matter, References and further reading

In particle physics, a collective term for heavy matter particles which experience strong interactions. Baryons are composed of three quarks. The least massive baryon is the proton, into which other baryons decay.

In particle physics, the baryons are the family of subatomic particles which are made of three quarks. The term "baryon" is derived from the Greek βαρύς (barys), meaning "heavy," because at the time of their naming it was believed that baryons were characterized by having greater mass than other particles.

Background

Baryons are strongly interacting fermions — that is, they experience the strong nuclear force and are described by Fermi-Dirac statistics, which apply to all particles obeying the Pauli exclusion principle.

Baryons, along with mesons, belong to the family of particles known as hadrons, meaning they are composed of quarks. Baryons are fermions composed of three quarks, while mesons are bosons composed of a quark and an antiquark. The quark model classification of baryons is based on this construction.

In addition to the nucleons (protons and neutrons), other members of the baryon family include the Δ, Λ, Σ, Ξ and Ω particles.

Delta baryons (Δ, Δ) are composed of a combination of up and down quarks such that the total spin is 3/2.

Lambda baryons (Λ0) are composed of one up, one down, and one strange quark, with the up and down quarks in an isospin 0 (flavor-antisymmetric) state.

Sigma baryons (Σ, Σ (up, up, strange) or Σ− (down, down, strange).

Xi baryons, (Ξ), are composed of two strange quarks and either an up or down quark.

The omega minus baryon (Ω−) is composed of three strange quarks.

There are additional baryon states which contain heavy quarks. (See: charmed baryons, bottom baryons.)

Baryonic matter

Baryonic matter is matter composed mostly of baryons (by mass), which includes atoms of any sort (and thus includes nearly all matter that we may encounter or experience in everyday life, including our bodies). Non-baryonic matter is the fundamental antithesis of such matter, being any sort of matter that is not primarily composed of baryons.

The very existence of baryons is also a significant problem in cosmology, since we have assumed that the Big Bang produced a state with equal amounts of baryons and anti-baryons.

References and further reading