History of Quantum Chromodynamics

In 1971 Gell-Mann and I introduced the color quantum number of the quarks. One year later we published a gauge theory, based on the gauge group SU(3) of the color transformations: Quantum Chromodynamics.  This theory describes the strong interactions and the nuclear forces. It is similar to quantum electrodynamics, but the gauge bosons of QCD, the gluons, interact not only with the quarks, but also with themselves. This leads to the phenomenon of asymptotic freedom - the coupling constant decreases at high energies.  At very high energies there should exist a new state of matter, the quark-gluon-plasma, e.g. inside massive neutron stars or in nucleus collisions at high energy.