Научно-исследовательский институт ядерной физики имени Д.В. Скобельцына
Московского государственного университета имени М.В. Ломоносова

We apply Bogolubov quasi-averages approach to QCD with two light quarks
to demonstrate a spontaneous generation of an effective interaction,
leading to the Nambu -- Jona-Lazinio model.
The resulting theory contain two parameters: average low-energy
value of $\\alpha_s$ and initial light quark mass $m_0$.
All other low-energy
parameters: the pion decay constant, the constituent quark
mass, the quark condensate, mass of the
$\\pi$-meson, mass of the $\\sigma$-meson and its width
are expressed in terms of the two
initial parameters in satisfactory correspondence to
experimental phenomenology.