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It is defined as = (¯), where is the number of quarks, and ¯ is the number of antiquarks. Baryons (three quarks) have a baryon number of +1, mesons (one quark, one antiquark) have a baryon number of 0, and antibaryons (three antiquarks) have a baryon number of −1.
Mesons named with the letter "f" are scalar mesons (as opposed to a pseudo-scalar meson), and mesons named with the letter "a" are axial-vector mesons (as opposed to an ordinary vector meson) a.k.a. an isoscalar vector meson, while the letters "b" and "h" refer to axial-vector mesons with positive parity, negative C-parity, and quantum numbers I G of 1 + and 0 − respectively.
Mesons are made of a valence quark–antiquark pair (thus have a baryon number of 0), while baryons are made of three quarks (thus have a baryon number of 1). This article discusses the quark model for the up, down, and strange flavors of quark (which form an approximate flavor SU(3) symmetry). There are generalizations to larger number of flavors.
Because quarks have a spin 1 / 2 , the difference in quark number between mesons and baryons results in conventional two-quark mesons being bosons, whereas baryons are fermions. Each type of meson has a corresponding antiparticle (antimeson) in which quarks are replaced by their corresponding antiquarks and vice versa.
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.
sigma baryons; Ξ ∗− and Ξ ∗0 xi baryons; Ω − omega baryon; However, one of the particles of this decuplet had never been previously observed when the eightfold way was proposed. Gell-Mann called this particle the Ω − and predicted in 1962 that it would have a strangeness −3, electric charge −1 and a mass near 1680 MeV/c 2.
QCD predicts that quarks and antiquarks bind into particles called mesons. Another type of hadron is called a baryon, that is made of three quarks. There is good experimental evidence for both mesons and baryons. Potentially QCD also has bound states of just gluons called glueballs.
A strange particle is an elementary particle with a strangeness quantum number different from zero. Strange particles are members of a large family of elementary particles carrying the quantum number of strangeness, including several cases where the quantum number is hidden in a strange/anti-strange pair, for example in the ϕ meson.