QCD vacuum structure in quark bag model

Different approaches to hadron spectroscopy are reviewed. A new quark model taking account of the quark interaction with the vacuum fields in a bag is developed. In frames of this model it is shown that the energy of quark containment in a hadron is defined by quark interaction with the long-wave vacuum fluctuations that specifies the scale of hadron masses. The internal structure of hadrons at small distances (r<0.2-0.3 fm is defined by potential of one-gluon exchange between quarks and at interstitial ones - by quark interaction with high-frequency vacuum fields approximated by instantons