NJL INTERACTION DERIVED FROM QCD

We apply Bogolubov approach to QCD with two light quarks to demonstrate a spontaneous generation of an effective interaction, leading to the Nambu–Jona-Lasinio model. The resulting theory contains two parameters: average low-energy value of α s and current light quark mass m 0 . All other low-energy parameters: the pion decay constant, mass of the π-meson, mass of the σ-meson and its width, the constituent quark mass, and the quark condensate are expressed in terms of the two input parameters in satisfactory correspondence to experimental data and chiral phenomenology. For example, in the approximation being used we have for α s = 0.67 and m 0 = 20 MeV : f π = 93 MeV , m π = 135 MeV , m σ = 492 MeV , Γ σ = 574 MeV , m q = 295 MeV , [Formula: see text].

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