ABSTRACT
This chapter describes the Standard Model of matter, electroweak and strong interactions and its vacuum. In the beginning of the 1930s, electron and positron were the only known leptons. In the years 1936/37, Anderson and Neddermeyer installed their spectrometer on Pike’s Peak, with an altitude of 4300m one of the highest summits in the Rocky Mountains. The high mass resolution of bubble chambers and the increasing energy reach of accelerators led to an explosion in the number of newly detected hadrons and resonances in the 1950s and 1960s. An organising pattern in the properties of mesons and baryons was found in group theory. Groups are formed by transformations, if their sequential application always leads to another member of the group. While the quark model was an elegant order scheme for the hadrons known at the end of the 1960s, its interpretation as a model for the internal structure of hadrons was far from generally accepted.
