Nonlinear sigma model approach for chiral fluctuations and symmetry   breakdown in Nambu-Jona-Lasinio model
  In this paper we discuss symmetry breakdown in NJL model at low N_c. In particular we propose a modified NJL model that displays a symmetry breakdown and also at finite temperatures under certain conditions the chiral fluctuations in this model give rise to a phase analogous to pseudogap phase of strong-coupling and low carrier density superconductors. 
Egor Babaev