Nambu—Jona-Lasinio model: an effective Lagrangian for quantum chromodynamics at intermediate length scales

A Nambu-Jona-Lasinio type model is proposed as an effective Lagrangian for quantum chromodynamics at intermediate length scales. It is shown that the SU(n)⊗SU(n) non-linear σ model, including the Wess-Zumino term, can be derived from it in the low-energy limit. Also presented is the effective nonminimal action whose minima correspond to baryons in the many-color limit