  The colored objects -- quarks and gluons -- being confined in a small volume
$V\sim R_0^3,$ $R_0\sim 0.5$fm inside the QCD bound state get there not small
masses $m_{q\bar q}\sim 1$GeV, $m_g\sim 0.5$GeV. This drastically simplifies
the QCD dynamics, as now the probabilities e.g. of production of one extra
massive valent gluon or extra $q\bar q$ pair, turned to be small due to a large
gap between corresponding energy levels. The ordinary quantum mechanical
perturbation theory calculations made in the paper shows that corresponding
dimensionless transition amplitudes
$\Lambda_{MH}=\frac{V_{MH}}{|E^{(0)}_M-E^{(0)}_H|}$ (from meson $q\bar q$ to
the hybrid $q\bar qg$) have a value of 20--25% and the mixing of hybrid with
glueball $(gg)$ is even smaller (of the order of 10--18%). Taking into account
all such mixings with all highly lying Fock states is equivalent to the exact
solution of QCD bound state problem. This can be done really summing the small
perturbation theory results for these states contributions.
