Quark
The quark model was independently proposed by physicists Murray Gell-Mann and George Zweig in 1964. Quarks were introduced as parts of an ordering scheme for hadrons, and there was little evidence for their physical existence until deep inelastic scattering experiments at the Stanford Linear Accelerator Center in 1968. Accelerator experiments have provided evidence for all six flavors. The top quark, first observed at Fermilab in 1995, was the last to be discovered.
Quantum chromodynamics
QCD exhibits two main properties:Physicist Murray Gell-Mann (b. 1929) coined the word "quark" in its present sense. It originally comes from the phrase "Three quarks for Muster Mark" in "Finnegans Wake" by James Joyce. On June 27, 1978, Gell-Mann wrote a private letter to the editor of the "Oxford English Dictionary", in which he related that he had been influenced by Joyce's words: "The allusion to three quarks seemed perfect." (Originally, only three quarks had been discovered.)