Quantum chromodynamics and hadronic mass scales

On the basis of the existing knowledge of the chromodynamic vacuum, mesons constructed from u, d, and s quarks and (or) gluons are investigated. A new classification of hadrons is proposed on the basis of the nature of the interaction of the constituent quarks and the gluons with the vacuum fields. It is found that the mass scale inherent in the resonance structures in the different channels is not universal; a large mass scale is found, for example, in the 0+- gluon channels. On the basis of the new classification a hierarchy of scales is established. The features of hadron phenomenology [Zweig's selection rule, approximate SU(6) symmetry, etc.] find a natural explanation. The properties of gluonium are discussed in some detail. Some low-energy theorems are derived and these give, in particular, a new mass relation for the eta' meson