Meson Effects on Chiral Condensate at Finite Density
  Meson corrections on chiral condensate up to next-to-leading order in $1/N_c$ expansion at finite density are investigated in NJL model with chiral symmetry explicitly breaking. Compared with the mean-field results, the chiral phase transition is still of first order, while the properties at the critical density of chiral phase transition are found to change significantly. 
Mei Huang, Pengfei Zhuang, Weiqin Chao