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A quark (/ k w ɔːr k, k w ɑːr k /) is a type of elementary particle and a fundamental constituent of matter. ... At the time of the quark theory's inception, ...
The electroweak sector is a Yang–Mills gauge theory with the symmetry group U(1) × SU(2) L, = ¯ + ¯ + ¯ + ¯ + ¯, where the subscript sums over the three generations of fermions; ,, and are the left-handed doublet, right-handed singlet up type, and right handed singlet down type quark fields; and and are the left-handed doublet and right ...
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.
A visual representation of the division order of universal forces. In physical cosmology, the quark epoch was the period in the evolution of the early universe when the fundamental interactions of gravitation, electromagnetism, the strong interaction and the weak interaction had taken their present forms, but the temperature of the universe was still too high to allow quarks to bind together ...
A quark may pair up with an antiquark: the quark has a color and the antiquark has the corresponding anticolor. The color and anticolor cancel out, forming a color neutral meson. Alternatively, three quarks can exist together, one quark being "red", another "blue", another "green". These three colored quarks together form a color-neutral baryon.
The name "quark" was coined by Gell-Mann, and is a reference to the novel Finnegans Wake, by James Joyce ("Three quarks for Muster Mark!" book 2, episode 4). book 2, episode 4). Zweig had referred to the particles as "aces", [ 50 ] but Gell-Mann's name caught on.
One such effective field theory is chiral perturbation theory or ChiPT, which is the QCD effective theory at low energies. More precisely, it is a low energy expansion based on the spontaneous chiral symmetry breaking of QCD, which is an exact symmetry when quark masses are equal to zero, but for the u, d and s quark, which have small mass, it ...
The intrinsic parity of the pion is P = −1 (since the pion is a bound state of a quark and an antiquark, which have opposite parities, with zero angular momentum), and parity is a multiplicative quantum number. Therefore, assuming the parent particle has zero spin, the two-pion and the three-pion final states have different parities (P = +1 ...