Four- and eight-fermion interactions in a space-time with non-trivial   topology
  The phase structure of an eight-fermion interaction model is investigated in a compact space-time with non-trivial topology, $M^{D-1}\otimes S^1$. The phase boundary dividing the symmetric and the broken phase is shown as a function of the space-time dimensions. It is found that the eight-fermion interaction does not modify the phase boundary for the chiral symmetry breaking. 
Tomohiro Inagaki