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All quarks are assigned a baryon number of 1 / 3 . Up, charm and top quarks have an electric charge of + 2 / 3 , while the down, strange, and bottom quarks have an electric charge of − 1 / 3 . Antiquarks have the opposite quantum numbers. Quarks are spin- 1 / 2 particles, and thus fermions. Each quark or antiquark ...
Exotic hadrons are subatomic particles composed of quarks and gluons, but which – unlike "well-known" hadrons such as protons, neutrons and mesons – consist of more than three valence quarks. By contrast, "ordinary" hadrons contain just two or three quarks. Hadrons with explicit valence gluon content would also be considered exotic. [1]
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.
An example would be pentaquarks, consisting of four quarks and one antiquark (qqqqq̅). So far, the only observed exotic baryons are the pentaquarks P c (4380) +, P c (4450) + discovered in 2015, [1] P c (4312) + in 2019 [2] and P Λ ψs (4338) 0 in 2022 by the LHCb collaboration. [3]
Omega baryons containing top quarks are also not expected to be observed. This is because the Standard Model predicts the mean lifetime of top quarks to be roughly 5 × 10 −25 s, [2] which is about a twentieth of the timescale necessary for the strong interactions required for Hadronization, the process by which hadrons form from quarks and ...
The neutrons and protons in the atomic nuclei are baryons – the neutron is composed of two down quarks and one up quark, and the proton is composed of two up quarks and one down quark. [29] A baryon is composed of three quarks, and a meson is composed of two quarks (one normal, one anti).
The current quark mass is also called the mass of the 'naked' quarks. The mass of the current quark is reduced by the term of the constituent quark covering mass.. The current quark mass is a logical consequence of the mathematical formalism of the quantum field theory (QFT), so the idea does not arise from a strictly descriptive report of observations.
Quarks have fractional electric charge values – either (− 1 / 3 ) or (+ 2 / 3 ) times the elementary charge (e), depending on flavor. Up, charm, and top quarks (collectively referred to as up-type quarks) have a charge of + 2 / 3 e; down, strange, and bottom quarks (down-type quarks) have a charge of − 1 / 3 e.