charm quark

The charm quark is one of six types, or "flavours," of quarks, which are elementary subatomic particles that are fundamental constituents of matter. Quarks interact via the strong force and combine to form hadrons, such as protons and neutrons. The charm quark, along with the strange quark, forms one of the three pairs of quarks, distinguished by their mass and charge characteristics.1

The concept of quarks was introduced in 1964 by Murray Gell-Mann and George Zweig as a way to explain the growing number of observed subatomic particles. Initially, it was unclear if quarks were real entities or just mathematical constructs, as they possess fractional electric charges (+2/3e or -1/3e) that were not directly detected. However, experiments in the mid-1970s provided evidence that quarks exist but are confined within hadrons, unable to escape as single particles. The charm quark has a charge of +2/3e and a mass between 1,000 and 1,600 MeV. The discovery of mesons containing charm quarks, like the J/psi particle, confirmed the existence of this flavour and supported the idea that quarks are related in pairs.213