Critical Behavior of a Four-Fermion Schwinger-Dyson Equation
  We study the Schwinger-Dyson equation associated with a chirality- changing fermion 4-point function in a strongly-coupled $U(1)$ gauge theory. After making appropriate simplifications, we solve the equation numerically via a relaxation method. Our analysis provides an estimate of the critical coupling and it gives some indication as to the general momentum dependence of the 4-point function. 
B. Holdom and G. Triantaphyllou (University of Toronto)