Quantum chromodynamics

Quantum Chromodynamics (QCD) is a quantum field theory of the strong interaction with non-abelian gauge fields mediating the interactions between quarks. The experimentally observed strong interactions are to be epiphenomena of these fundamental interactions. The experimental successes of QCD form the basis for the present optimism that a theory of the strong force has been found. However, QCD is still very vulnerable to default on both experimental and theoretical grounds. This article reviews the properties and attempted solutions of QCD. Most of the major areas of interest in QCD are covered; the prime exceptions are lattice gauge theories and phenomenological QCD like the parton and potential models. (Auth.)