Charm quark

The charm quark is a particle of matter. It is one of the six quarks in the standard modeland is considered to be an elementary particle in our current state of knowledge.

The charm quark is one of the six quarks, the others being :

• the up quark;
• the top quark;
• the bottom quark;
• the strange quark;
• the down quark.

The charm quark

Like its companions it is a fermion; it has a fractional electrical charge equal to 2/3 e. It is not one of the first three quarks postulated at the beginning of the 1960s independently by Gell-Mann, Yuval Ne'eman and George Zweig to understand and classify the hadrons that were known at the time. It is also called the c ( charm) quark.

Two of the discoverers of quark theory. © universe-review

The existence of the quark was predicted in 1970 by Sheldon Glashow, Jean Iliopoulos and Luciano Maiani. The first experimental proof of its existence was observed in 1974 by a team at the Stanford Linear Accelerator Center (SLAC) led by Burton Richter, and another at the Brookhaven National Laboratory (BNL), led by Samuel Ting. Currently it is part of what is called the second generation of particles in the standard model.

The existence of the c quark only started being accepted in the 1960s and especially the beginning of the 1970s when the theory of quark confinement partially explained why quarks were never observed free, but only inside hadrons.