Charm quark

The charm quark, charmed quark, or c quark is an <a href="/facts/Elementary_particle/CTFDM97U">elementary particle</a> found in composite subatomic particles called <a href="/facts/Hadron/C0sd1zty">hadrons</a> such as the <a href="/facts/J%2fpsi_meson/gPC3MUrM">J/psi meson</a> and the <a href="/facts/Charmed_baryon/YonzMLph">charmed baryons</a> created in particle accelerator collisions. Several <a href="/facts/Boson/XtPFcjb5">bosons</a>, including the <a href="/facts/W_and_Z_bosons/gAncY5XV">W and Z bosons</a> and the <a href="/facts/Higgs_boson/3LAYXfft">Higgs boson</a>, can decay into charm quarks. All charm quarks carry <a href="/facts/Charm_(quantum_number)/zDxKQ5We">charm</a>, a <a href="/facts/Quantum_number/AByP6F0y">quantum number</a>. This second-<a href="/facts/Generation_(particle_physics)/hAbgvUfV">generation</a> particle is the third-most-massive <a href="/facts/Quark/hwuuVkV5">quark</a>, with a mass of 1.27±0.02 <a href="/facts/Electronvolt/YMT1fqX9">GeV/c2</a> as measured in 2022, and a charge of +⁠2/3⁠ <a href="/facts/Elementary_charge/lPcj6CoQ">e</a>.
The existence of the charm quark was first predicted by <a href="/facts/James_Bjorken/qoATKRrK">James Bjorken</a> and <a href="/facts/Sheldon_Glashow/KNS7qjog">Sheldon Glashow</a> in 1964, and in 1970, Glashow, <a href="/facts/John_Iliopoulos/FKNhoVPN">John Iliopoulos</a>, and <a href="/facts/Luciano_Maiani/3hgcWyvK">Luciano Maiani</a> showed how its existence would account for experimental and theoretical discrepancies. In 1974, its existence was confirmed through the independent discoveries of the <a href="/facts/J%2fpsi_meson/gPC3MUrM">J/psi meson</a> at <a href="/facts/Brookhaven_National_Laboratory/L2JrG0K1">Brookhaven National Laboratory</a> and the <a href="/facts/Stanford_Linear_Accelerator_Center/CzX2afas">Stanford Linear Accelerator Center</a>. In the next few years, several other charmed particles, including the <a href="/facts/D_meson/o6pW8BLc">D meson</a> and the charmed strange mesons, were found.
In the 21st century, a <a href="/facts/Baryon/QFwAUWK2">baryon</a> containing two charm quarks has been found. There is recent evidence that intrinsic charm quarks exist in the <a href="/facts/Proton/clCjepXP">proton</a>, and the coupling of the charm quark and the Higgs boson has been studied. Recent evidence also indicates <a href="/facts/CP_violation/Nu5lCsPI">CP violation</a> in the decay of the D0 meson, which contains the charm quark.

Charm quark open-in-new

Charm quark