Charm quark

Charm quark

Composition	Elementary particle
Statistics	Fermion
Family	Quark
Generation	Second
Interactions	strong, electromagnetic, weak, gravity
Symbol	c
Antiparticle	Charm antiquark ( c )
Theorized	James Bjorken, Sheldon Glashow (1964) Sheldon Glashow, John Iliopoulos, Luciano Maiani (1970)
Discovered	Samuel C. C. Ting et al. (BNL, 1974) Burton Richter et al. (SLAC, 1974)
Mass	1.27±0.02 GeV/c2
Electric charge	+⁠2/3⁠ e
Color charge	Yes
Spin	⁠1/2⁠ ħ
Weak isospin	LH: +⁠1/2⁠, RH: 0
Weak hypercharge	LH: +⁠1/3⁠, RH: +⁠4/3⁠

Standard Model of particle physics
Elementary particles of the Standard Model
Background Particle physics Standard Model Quantum field theory Gauge theory Spontaneous symmetry breaking Higgs mechanism
Constituents Electroweak interaction Quantum chromodynamics CKM matrix Standard Model mathematics
Limitations Strong CP problem Hierarchy problem Neutrino oscillations Physics beyond the Standard Model
Scientists Rutherford Thomson Chadwick Bose Sudarshan Davis Jr Anderson Fermi Dirac Feynman Rubbia Gell-Mann Kendall Taylor Friedman Powell Anderson Glashow Iliopoulos Lederman Maiani Meer Cowan Nambu Chamberlain Cabibbo Schwartz Perl Majorana Weinberg Lee Ward Salam Kobayashi Maskawa Mills Yang Yukawa 't Hooft Veltman Gross Pais Pauli Politzer Reines Schwinger Wilczek Cronin Fitch Vleck Higgs Englert Brout Hagen Guralnik Kibble de Mayolo Lattes Zweig
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The charm quark, charmed quark, or c quark is an elementary particle found in composite subatomic particles called hadrons such as the J/psi meson and the charmed baryons created in particle accelerator collisions. Several bosons, including the W and Z bosons and the Higgs boson, can decay into charm quarks. All charm quarks carry charm, a quantum number. This second-generation particle is the third-most-massive quark, with a mass of 1.27±0.02 GeV/c² as measured in 2022, and a charge of +⁠2/3⁠ e.

The existence of the charm quark was first predicted by James Bjorken and Sheldon Glashow in 1964,^[1][2][3] and in 1970, Glashow, John Iliopoulos, and Luciano Maiani showed how its existence would account for experimental and theoretical discrepancies.^[4] 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 D⁰ meson, which contains the charm quark.