Editing Charm quark (section)

{{Short description|Type of quark}}
{{Redirect|Charm (physics)||Charm (disambiguation)#Science and technology}}
{{good article}}
{{Infobox Particle
 |bgcolour =
 |name = Charm quark
 |image = [[File:Charm quark.svg|150px]]
 |caption =
 |num_types =
 |composition = [[Elementary particle]]
 |statistics = [[Fermion]]
 |group = [[Quark]]
 |generation = Second
 |interaction = [[Strong interaction|strong]], [[Electromagnetism|electromagnetic]], [[Weak interaction|weak]], [[gravity]]
 |particle =
 |antiparticle = Charm antiquark ({{SubatomicParticle|Charm antiquark}})
 |theorized =
{{plainlist|
* [[James Bjorken]], [[Sheldon Glashow]] (1964)
* Sheldon Glashow, [[John Iliopoulos]], [[Luciano Maiani]] (1970)
}}
 |discovered =
{{plainlist|
* [[Samuel C. C. Ting]] ''et al.'' ([[Brookhaven National Laboratory|BNL]], 1974)
* [[Burton Richter]] ''et al.'' ([[SLAC]], 1974)
}}
 |symbol = {{SubatomicParticle|Charm quark}}
 |mass = {{val|1.27|0.02|ul=GeV/c2}}
 |decay_time =
 |decay_particle = 
 |electric_charge = +{{sfrac|2|3}} [[Elementary charge|''e'']]
 |color_charge = Yes
 |spin = {{sfrac|1|2}}&nbsp;[[Reduced Planck constant|''ħ'']]
 |num_spin_states =
 |weak_isospin = {{nowrap|[[Chirality (physics)|LH]]: +{{sfrac|1|2}}, [[Chirality (physics)|RH]]: 0}}
 |weak_hypercharge= {{nowrap|[[Chirality (physics)|LH]]: +{{sfrac|1|3}}, [[Chirality (physics)|RH]]: +{{sfrac|4|3}}}}
}}
{{Standard model of particle physics}}

The '''charm quark''', '''charmed quark''', or '''c quark''' is an [[elementary particle]] found in composite subatomic particles called [[hadron]]s such as the [[J/psi meson]] and the [[charmed baryon]]s created in particle accelerator collisions. Several [[boson]]s, including the [[W and Z bosons]] and the [[Higgs boson]], can decay into charm quarks. All charm quarks carry [[Charm (quantum number)|charm]], a [[quantum number]]. This second-[[Generation (particle physics)|generation]] particle is the third-most-massive [[quark]], with a mass of {{val|1.27|0.02|ul=GeV/c2}} as measured in 2022, and a charge of&nbsp;+{{sfrac|2|3}}&nbsp;[[Elementary charge|''e'']].

The existence of the charm quark was first predicted by [[James Bjorken]] and [[Sheldon Glashow]] in 1964,{{sfn|Amati|Bacry|Nuyts|Prentki|1964}}{{sfn|Maki|Ohnuki|1964}}{{sfn|Hara|1964}} and in 1970, Glashow, [[John Iliopoulos]], and [[Luciano Maiani]] showed how its existence would account for experimental and theoretical discrepancies.{{sfn|Glashow|Iliopoulos|Maiani|1970|p=1287}} In 1974, its existence was confirmed through the independent discoveries of the [[J/psi meson]] at [[Brookhaven National Laboratory]] and the [[Stanford Linear Accelerator Center]]. In the next few years, several other charmed particles, including the [[D meson]] and the charmed strange mesons, were found.

In the 21st century, a [[baryon]] containing two charm quarks has been found. There is recent evidence that intrinsic charm quarks exist in the [[proton]], and the coupling of the charm quark and the Higgs boson has been studied. Recent evidence also indicates [[CP violation]] in the decay of the D<sup>0</sup>&nbsp;meson, which contains the charm quark.

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