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# Charm quark

Composition: Charm Quark Elementary particle Fermion Quark Second Glashow, Iliopoulos, Maiani, 1970 Burton Richter et al. and Samuel C. C. Ting et al., 1974 1.3 GeV/c2 +2/3 e ½
 Flavour in particle physicsv • d • e Flavour quantum numbers: Lepton number: L Baryon number: B Strangeness: S Charm: C Bottomness: B' Topness: T Isospin: Iz or I Weak isospin: Tz Electric charge: Q Combinations: Hypercharge: Y Y=2(Q-Iz) Weak hypercharge: YW YW=2(Q-Tz) YW=B−L Related topics: CPT symmetry CKM matrix CP symmetry Chirality

The charm quark is a second-generation quark with a charge of +(2/3)e. It is the third most massive of the quarks, at 1.3 GeV (a bit more than the mass of the proton). It was predicted in 1970 by Sheldon Glashow, John Iliopoulos, and Luciano Maiani, and first observed in November 1974, with the simultaneous discovery of the J/ψ charm particle at SLAC (Stanford Linear Accererator Center) by a group led by Burton Richter and at BNL (Brookhaven National Laboratory) by a group led by Samuel C. C. Ting. The particle was named J by the BNL group and ψ by the SLAC group; when the naming controversy could not be resolved, the compromise J/ψ was adopted.

$C = N_c - N_{\overline{c}}$