Chiral Symmetry Breaking in the $d=3$ Nambu-Jona-Lasinio Model in Curved   Spacetime
  The phase structure of the $d=3$ Nambu-Jona-Lasinio model in curved spacetime is considered to leading order in the $1/N$--expansion and in the linear curvature approximation. The possibility of a curvature-induced first-order phase transition is investigated numerically. The dynamically generated fermionic mass is calculated for some values of the curvature. 
E. Elizalde, S.D. Odintsov and Yu.I. Shil'nov