The quarkoniums are

mesons each made of a

quark and the corresponding

antiquark. Is the ideal

system for studying the

strong interquark

color force.

The most

important example of this in the

history of

particle physics is the

J/Psi particle (made up of a

charm and anti

charm quark), discovered in November

1974 at a

center-of-mass-energy of 3.1

GeV/c^2. Normally, quarks in

hadrons move with a

speed near that of light, and

calculations of their properties must be done using the

complicated equations of

relativistic quantum mechanics. But this system proved particularly useful because it the charm quark is

massive enough so that in this J/Psi

bound state, they're moving slow enough so you can

neglect relativistic effects. In this J/Psi "

charmonium" system, the

math is much easier, and the details of the interquark

force are easier to

study.

This '

November Revolution' of 1974 led particle physics in new directions.

Feynman's

QED was extended, and

Quantum Chromodynamics (

QCD) came of age. The

discovery of the charmed quark in the J/Psi system

stimmulated the search for yet heavier quarks, and in 1977, the

bottom quark was found at

Fermilab in the analogous quarkonium system,

bottomonium (the Upsilon particle, m = 9.46

GeV/c^2).