Elementarteilchen mit Charm

Several theoretical models have been proposed to explain the new heavy mesons discovered in 1974, among them the charm model and the color model. Recent experiments strongly support the charm model. Following the historical development from isospin-symmetry SU(2) over isospin-strangeness-symmetry SU(3) to isospin-strangeness-charm-symmetry SU(4), the present article discusses the basic assumptions of the model and its predictions concerning the production and decay of charmed particles. In a second article the current status of the model's experimental verification is reviewed.